Create a new ImagePackager tools class

Pull functionality from `Repackager` into a new `Packager` base class
and develop a variant for Docker image creation. The new `ImagePackager`
class provides a general purpose way to construct jar entries without
being tied to an actual file. This will allow us to link it to a
buildpack and provide application content directly.

Closes gh-19834

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/build.gradle

@@ -16,11 +16,10 @@ configurations {
 dependencies {
 	api platform(project(':spring-boot-project:spring-boot-parent'))
 	api "org.apache.commons:commons-compress"
+	api "org.springframework:spring-core"
 
 	compileOnly "ch.qos.logback:logback-classic"
 
-	implementation "org.springframework:spring-core"
-
 	loader project(":spring-boot-project:spring-boot-tools:spring-boot-loader")
 
 	testImplementation "org.assertj:assertj-core"

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/AbstractJarWriter.java

@@ -0,0 +1,388 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedWriter;
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.io.OutputStreamWriter;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.Enumeration;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.jar.JarInputStream;
+import java.util.jar.Manifest;
+import java.util.zip.CRC32;
+import java.util.zip.ZipEntry;
+
+import org.apache.commons.compress.archivers.jar.JarArchiveEntry;
+import org.apache.commons.compress.archivers.zip.UnixStat;
+
+/**
+ * Abstract base class for JAR writers.
+ *
+ * @author Phillip Webb
+ * @author Andy Wilkinson
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public abstract class AbstractJarWriter implements LoaderClassesWriter {
+
+	private static final String NESTED_LOADER_JAR = "META-INF/loader/spring-boot-loader.jar";
+
+	private static final int BUFFER_SIZE = 32 * 1024;
+
+	private static final int UNIX_FILE_MODE = UnixStat.FILE_FLAG | UnixStat.DEFAULT_FILE_PERM;
+
+	private static final int UNIX_DIR_MODE = UnixStat.DIR_FLAG | UnixStat.DEFAULT_DIR_PERM;
+
+	private final Set<String> writtenEntries = new HashSet<>();
+
+	/**
+	 * Write the specified manifest.
+	 * @param manifest the manifest to write
+	 * @throws IOException of the manifest cannot be written
+	 */
+	public void writeManifest(Manifest manifest) throws IOException {
+		JarArchiveEntry entry = new JarArchiveEntry("META-INF/MANIFEST.MF");
+		writeEntry(entry, manifest::write);
+	}
+
+	/**
+	 * Write all entries from the specified jar file.
+	 * @param jarFile the source jar file
+	 * @throws IOException if the entries cannot be written
+	 */
+	public void writeEntries(JarFile jarFile) throws IOException {
+		this.writeEntries(jarFile, EntryTransformer.NONE, UnpackHandler.NEVER);
+	}
+
+	final void writeEntries(JarFile jarFile, EntryTransformer entryTransformer, UnpackHandler unpackHandler)
+			throws IOException {
+		Enumeration<JarEntry> entries = jarFile.entries();
+		while (entries.hasMoreElements()) {
+			JarArchiveEntry entry = new JarArchiveEntry(entries.nextElement());
+			setUpEntry(jarFile, entry);
+			try (ZipHeaderPeekInputStream inputStream = new ZipHeaderPeekInputStream(jarFile.getInputStream(entry))) {
+				EntryWriter entryWriter = new InputStreamEntryWriter(inputStream);
+				JarArchiveEntry transformedEntry = entryTransformer.transform(entry);
+				if (transformedEntry != null) {
+					writeEntry(transformedEntry, entryWriter, unpackHandler);
+				}
+			}
+		}
+	}
+
+	private void setUpEntry(JarFile jarFile, JarArchiveEntry entry) throws IOException {
+		try (ZipHeaderPeekInputStream inputStream = new ZipHeaderPeekInputStream(jarFile.getInputStream(entry))) {
+			if (inputStream.hasZipHeader() && entry.getMethod() != ZipEntry.STORED) {
+				new CrcAndSize(inputStream).setupStoredEntry(entry);
+			}
+			else {
+				entry.setCompressedSize(-1);
+			}
+		}
+	}
+
+	/**
+	 * Writes an entry. The {@code inputStream} is closed once the entry has been written
+	 * @param entryName the name of the entry
+	 * @param inputStream the stream from which the entry's data can be read
+	 * @throws IOException if the write fails
+	 */
+	@Override
+	public void writeEntry(String entryName, InputStream inputStream) throws IOException {
+		JarArchiveEntry entry = new JarArchiveEntry(entryName);
+		try {
+			writeEntry(entry, new InputStreamEntryWriter(inputStream));
+		}
+		finally {
+			inputStream.close();
+		}
+	}
+
+	/**
+	 * Write a nested library.
+	 * @param destination the destination of the library
+	 * @param library the library
+	 * @throws IOException if the write fails
+	 */
+	public void writeNestedLibrary(String destination, Library library) throws IOException {
+		File file = library.getFile();
+		JarArchiveEntry entry = new JarArchiveEntry(destination + library.getName());
+		entry.setTime(getNestedLibraryTime(file));
+		new CrcAndSize(file).setupStoredEntry(entry);
+		try (FileInputStream input = new FileInputStream(file)) {
+			writeEntry(entry, new InputStreamEntryWriter(input), new LibraryUnpackHandler(library));
+		}
+	}
+
+	/**
+	 * Write a simple index file containing the specified UTF-8 lines.
+	 * @param location the location of the index file
+	 * @param lines the lines to write
+	 * @throws IOException if the write fails
+	 * @since 2.3.0
+	 */
+	public void writeIndexFile(String location, List<String> lines) throws IOException {
+		if (location != null) {
+			JarArchiveEntry entry = new JarArchiveEntry(location);
+			writeEntry(entry, (outputStream) -> {
+				BufferedWriter writer = new BufferedWriter(
+						new OutputStreamWriter(outputStream, StandardCharsets.UTF_8));
+				for (String line : lines) {
+					writer.write(line);
+					writer.write("\n");
+				}
+				writer.flush();
+			});
+		}
+	}
+
+	private long getNestedLibraryTime(File file) {
+		try {
+			try (JarFile jarFile = new JarFile(file)) {
+				Enumeration<JarEntry> entries = jarFile.entries();
+				while (entries.hasMoreElements()) {
+					JarEntry entry = entries.nextElement();
+					if (!entry.isDirectory()) {
+						return entry.getTime();
+					}
+				}
+			}
+		}
+		catch (Exception ex) {
+			// Ignore and just use the source file timestamp
+		}
+		return file.lastModified();
+	}
+
+	/**
+	 * Write the required spring-boot-loader classes to the JAR.
+	 * @throws IOException if the classes cannot be written
+	 */
+	@Override
+	public void writeLoaderClasses() throws IOException {
+		writeLoaderClasses(NESTED_LOADER_JAR);
+	}
+
+	/**
+	 * Write the required spring-boot-loader classes to the JAR.
+	 * @param loaderJarResourceName the name of the resource containing the loader classes
+	 * to be written
+	 * @throws IOException if the classes cannot be written
+	 */
+	@Override
+	public void writeLoaderClasses(String loaderJarResourceName) throws IOException {
+		URL loaderJar = getClass().getClassLoader().getResource(loaderJarResourceName);
+		try (JarInputStream inputStream = new JarInputStream(new BufferedInputStream(loaderJar.openStream()))) {
+			JarEntry entry;
+			while ((entry = inputStream.getNextJarEntry()) != null) {
+				if (entry.getName().endsWith(".class")) {
+					writeEntry(new JarArchiveEntry(entry), new InputStreamEntryWriter(inputStream));
+				}
+			}
+		}
+	}
+
+	private void writeEntry(JarArchiveEntry entry, EntryWriter entryWriter) throws IOException {
+		writeEntry(entry, entryWriter, UnpackHandler.NEVER);
+	}
+
+	/**
+	 * Perform the actual write of a {@link JarEntry}. All other write methods delegate to
+	 * this one.
+	 * @param entry the entry to write
+	 * @param entryWriter the entry writer or {@code null} if there is no content
+	 * @param unpackHandler handles possible unpacking for the entry
+	 * @throws IOException in case of I/O errors
+	 */
+	private void writeEntry(JarArchiveEntry entry, EntryWriter entryWriter, UnpackHandler unpackHandler)
+			throws IOException {
+		String name = entry.getName();
+		writeParentFolderEntries(name);
+		if (this.writtenEntries.add(name)) {
+			entry.setUnixMode(name.endsWith("/") ? UNIX_DIR_MODE : UNIX_FILE_MODE);
+			entry.getGeneralPurposeBit().useUTF8ForNames(true);
+			if (!entry.isDirectory() && entry.getSize() == -1) {
+				entryWriter = SizeCalculatingEntryWriter.get(entryWriter);
+				entry.setSize(entryWriter.size());
+			}
+			entryWriter = addUnpackCommentIfNecessary(entry, entryWriter, unpackHandler);
+			writeToArchive(entry, entryWriter);
+		}
+	}
+
+	protected abstract void writeToArchive(ZipEntry entry, EntryWriter entryWriter) throws IOException;
+
+	private void writeParentFolderEntries(String name) throws IOException {
+		String parent = name.endsWith("/") ? name.substring(0, name.length() - 1) : name;
+		while (parent.lastIndexOf('/') != -1) {
+			parent = parent.substring(0, parent.lastIndexOf('/'));
+			if (!parent.isEmpty()) {
+				writeEntry(new JarArchiveEntry(parent + "/"), null, UnpackHandler.NEVER);
+			}
+		}
+	}
+
+	private EntryWriter addUnpackCommentIfNecessary(JarArchiveEntry entry, EntryWriter entryWriter,
+			UnpackHandler unpackHandler) throws IOException {
+		if (entryWriter == null || !unpackHandler.requiresUnpack(entry.getName())) {
+			return entryWriter;
+		}
+		ByteArrayOutputStream output = new ByteArrayOutputStream();
+		entryWriter.write(output);
+		entry.setComment("UNPACK:" + unpackHandler.sha1Hash(entry.getName()));
+		return new InputStreamEntryWriter(new ByteArrayInputStream(output.toByteArray()));
+	}
+
+	/**
+	 * {@link EntryWriter} that writes content from an {@link InputStream}.
+	 */
+	private static class InputStreamEntryWriter implements EntryWriter {
+
+		private final InputStream inputStream;
+
+		InputStreamEntryWriter(InputStream inputStream) {
+			this.inputStream = inputStream;
+		}
+
+		@Override
+		public void write(OutputStream outputStream) throws IOException {
+			byte[] buffer = new byte[BUFFER_SIZE];
+			int bytesRead;
+			while ((bytesRead = this.inputStream.read(buffer)) != -1) {
+				outputStream.write(buffer, 0, bytesRead);
+			}
+			outputStream.flush();
+		}
+
+	}
+
+	/**
+	 * Data holder for CRC and Size.
+	 */
+	private static class CrcAndSize {
+
+		private final CRC32 crc = new CRC32();
+
+		private long size;
+
+		CrcAndSize(File file) throws IOException {
+			try (FileInputStream inputStream = new FileInputStream(file)) {
+				load(inputStream);
+			}
+		}
+
+		CrcAndSize(InputStream inputStream) throws IOException {
+			load(inputStream);
+		}
+
+		private void load(InputStream inputStream) throws IOException {
+			byte[] buffer = new byte[BUFFER_SIZE];
+			int bytesRead;
+			while ((bytesRead = inputStream.read(buffer)) != -1) {
+				this.crc.update(buffer, 0, bytesRead);
+				this.size += bytesRead;
+			}
+		}
+
+		void setupStoredEntry(JarArchiveEntry entry) {
+			entry.setSize(this.size);
+			entry.setCompressedSize(this.size);
+			entry.setCrc(this.crc.getValue());
+			entry.setMethod(ZipEntry.STORED);
+		}
+
+	}
+
+	/**
+	 * An {@code EntryTransformer} enables the transformation of {@link JarEntry jar
+	 * entries} during the writing process.
+	 */
+	@FunctionalInterface
+	interface EntryTransformer {
+
+		/**
+		 * No-op entity transformer.
+		 */
+		EntryTransformer NONE = (jarEntry) -> jarEntry;
+
+		JarArchiveEntry transform(JarArchiveEntry jarEntry);
+
+	}
+
+	/**
+	 * An {@code UnpackHandler} determines whether or not unpacking is required and
+	 * provides a SHA1 hash if required.
+	 */
+	interface UnpackHandler {
+
+		UnpackHandler NEVER = new UnpackHandler() {
+
+			@Override
+			public boolean requiresUnpack(String name) {
+				return false;
+			}
+
+			@Override
+			public String sha1Hash(String name) throws IOException {
+				throw new UnsupportedOperationException();
+			}
+
+		};
+
+		boolean requiresUnpack(String name);
+
+		String sha1Hash(String name) throws IOException;
+
+	}
+
+	/**
+	 * {@link UnpackHandler} backed by a {@link Library}.
+	 */
+	private static final class LibraryUnpackHandler implements UnpackHandler {
+
+		private final Library library;
+
+		private LibraryUnpackHandler(Library library) {
+			this.library = library;
+		}
+
+		@Override
+		public boolean requiresUnpack(String name) {
+			return this.library.isUnpackRequired();
+		}
+
+		@Override
+		public String sha1Hash(String name) throws IOException {
+			return FileUtils.sha1Hash(this.library.getFile());
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/EntryWriter.java

@@ -0,0 +1,47 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * Interface used to write jar entry data.
+ *
+ * @author Phillip Webb
+ * @since 2.3.0
+ */
+@FunctionalInterface
+public interface EntryWriter {
+
+	/**
+	 * Write entry data to the specified output stream.
+	 * @param outputStream the destination for the data
+	 * @throws IOException in case of I/O errors
+	 */
+	void write(OutputStream outputStream) throws IOException;
+
+	/**
+	 * Return the size of the content that will be written, or {@code -1} if the size is
+	 * not known.
+	 * @return the size of the content
+	 */
+	default int size() {
+		return -1;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/ImagePackager.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.function.BiConsumer;
+import java.util.jar.JarFile;
+import java.util.zip.ZipEntry;
+
+import org.springframework.util.Assert;
+
+/**
+ * Utility class that can be used to export a fully packaged archive to an OCI image.
+ *
+ * @author Phillip Webb
+ * @since 2.3.0
+ */
+public class ImagePackager extends Packager {
+
+	/**
+	 * Create a new {@link ImagePackager} instance.
+	 * @param source the source file to package
+	 */
+	public ImagePackager(File source) {
+		super(source, null);
+	}
+
+	/**
+	 * Create an packaged image.
+	 * @param libraries the contained libraries
+	 * @param exporter the exporter used to write the image
+	 * @throws IOException on IO error
+	 */
+	public void packageImage(Libraries libraries, BiConsumer<ZipEntry, EntryWriter> exporter) throws IOException {
+		packageImage(libraries, new DelegatingJarWriter(exporter));
+	}
+
+	private void packageImage(Libraries libraries, AbstractJarWriter writer) throws IOException {
+		File source = isAlreadyPackaged() ? getBackupFile() : getSource();
+		Assert.state(source.exists() && source.isFile(), "Unable to read jar file " + source);
+		Assert.state(!isAlreadyPackaged(source), "Repackaged jar file " + source + " cannot be exported");
+		try (JarFile sourceJar = new JarFile(source)) {
+			write(sourceJar, libraries, writer);
+		}
+	}
+
+	/**
+	 * {@link AbstractJarWriter} that delegates to a {@link BiConsumer}.
+	 */
+	private static class DelegatingJarWriter extends AbstractJarWriter {
+
+		private BiConsumer<ZipEntry, EntryWriter> exporter;
+
+		DelegatingJarWriter(BiConsumer<ZipEntry, EntryWriter> exporter) {
+			this.exporter = exporter;
+		}
+
+		@Override
+		protected void writeToArchive(ZipEntry entry, EntryWriter entryWriter) throws IOException {
+			this.exporter.accept(entry, entryWriter);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/JarWriter.java

@@ -16,39 +16,20 @@
 
 package org.springframework.boot.loader.tools;
 
-import java.io.BufferedInputStream;
-import java.io.BufferedWriter;
-import java.io.ByteArrayInputStream;
-import java.io.ByteArrayOutputStream;
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.FileNotFoundException;
 import java.io.FileOutputStream;
-import java.io.FilterInputStream;
 import java.io.IOException;
-import java.io.InputStream;
-import java.io.OutputStream;
-import java.io.OutputStreamWriter;
-import java.net.URL;
-import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.attribute.PosixFilePermission;
-import java.util.Arrays;
-import java.util.Enumeration;
 import java.util.HashSet;
-import java.util.List;
 import java.util.Set;
-import java.util.jar.JarEntry;
-import java.util.jar.JarFile;
-import java.util.jar.JarInputStream;
-import java.util.jar.Manifest;
-import java.util.zip.CRC32;
 import java.util.zip.ZipEntry;
+import java.util.zip.ZipException;
 
 import org.apache.commons.compress.archivers.jar.JarArchiveEntry;
 import org.apache.commons.compress.archivers.jar.JarArchiveOutputStream;
-import org.apache.commons.compress.archivers.zip.UnixStat;
 
 /**
  * Writes JAR content, ensuring valid directory entries are always created and duplicate
@@ -59,19 +40,9 @@ import org.apache.commons.compress.archivers.zip.UnixStat;
  * @author Madhura Bhave
  * @since 1.0.0
  */
-public class JarWriter implements LoaderClassesWriter, AutoCloseable {
+public class JarWriter extends AbstractJarWriter implements AutoCloseable {
 
-	private static final String NESTED_LOADER_JAR = "META-INF/loader/spring-boot-loader.jar";
-
-	private static final int BUFFER_SIZE = 32 * 1024;
-
-	private static final int UNIX_FILE_MODE = UnixStat.FILE_FLAG | UnixStat.DEFAULT_FILE_PERM;
-
-	private static final int UNIX_DIR_MODE = UnixStat.DIR_FLAG | UnixStat.DEFAULT_DIR_PERM;
-
-	private final JarArchiveOutputStream jarOutput;
-
-	private final Set<String> writtenEntries = new HashSet<>();
+	private final JarArchiveOutputStream jarOutputStream;
 
 	/**
 	 * Create a new {@link JarWriter} instance.
@@ -96,8 +67,8 @@ public class JarWriter implements LoaderClassesWriter, AutoCloseable {
 			fileOutputStream.write(launchScript.toByteArray());
 			setExecutableFilePermission(file);
 		}
-		this.jarOutput = new JarArchiveOutputStream(fileOutputStream);
-		this.jarOutput.setEncoding("UTF-8");
+		this.jarOutputStream = new JarArchiveOutputStream(fileOutputStream);
+		this.jarOutputStream.setEncoding("UTF-8");
 	}
 
 	private void setExecutableFilePermission(File file) {
@@ -112,155 +83,20 @@ public class JarWriter implements LoaderClassesWriter, AutoCloseable {
 		}
 	}
 
-	/**
-	 * Write the specified manifest.
-	 * @param manifest the manifest to write
-	 * @throws IOException of the manifest cannot be written
-	 */
-	public void writeManifest(Manifest manifest) throws IOException {
-		JarArchiveEntry entry = new JarArchiveEntry("META-INF/MANIFEST.MF");
-		writeEntry(entry, manifest::write);
-	}
-
-	/**
-	 * Write all entries from the specified jar file.
-	 * @param jarFile the source jar file
-	 * @throws IOException if the entries cannot be written
-	 */
-	public void writeEntries(JarFile jarFile) throws IOException {
-		this.writeEntries(jarFile, EntryTransformer.NONE, UnpackHandler.NEVER);
-	}
-
-	void writeEntries(JarFile jarFile, UnpackHandler unpackHandler) throws IOException {
-		this.writeEntries(jarFile, EntryTransformer.NONE, unpackHandler);
-	}
-
-	void writeEntries(JarFile jarFile, EntryTransformer entryTransformer, UnpackHandler unpackHandler)
-			throws IOException {
-		Enumeration<JarEntry> entries = jarFile.entries();
-		while (entries.hasMoreElements()) {
-			JarArchiveEntry entry = new JarArchiveEntry(entries.nextElement());
-			setUpEntry(jarFile, entry);
-			try (ZipHeaderPeekInputStream inputStream = new ZipHeaderPeekInputStream(jarFile.getInputStream(entry))) {
-				EntryWriter entryWriter = new InputStreamEntryWriter(inputStream);
-				JarArchiveEntry transformedEntry = entryTransformer.transform(entry);
-				if (transformedEntry != null) {
-					writeEntry(transformedEntry, entryWriter, unpackHandler);
-				}
-			}
-		}
-	}
-
-	private void setUpEntry(JarFile jarFile, JarArchiveEntry entry) throws IOException {
-		try (ZipHeaderPeekInputStream inputStream = new ZipHeaderPeekInputStream(jarFile.getInputStream(entry))) {
-			if (inputStream.hasZipHeader() && entry.getMethod() != ZipEntry.STORED) {
-				new CrcAndSize(inputStream).setupStoredEntry(entry);
-			}
-			else {
-				entry.setCompressedSize(-1);
-			}
-		}
-	}
-
-	/**
-	 * Writes an entry. The {@code inputStream} is closed once the entry has been written
-	 * @param entryName the name of the entry
-	 * @param inputStream the stream from which the entry's data can be read
-	 * @throws IOException if the write fails
-	 */
 	@Override
-	public void writeEntry(String entryName, InputStream inputStream) throws IOException {
-		JarArchiveEntry entry = new JarArchiveEntry(entryName);
-		try {
-			writeEntry(entry, new InputStreamEntryWriter(inputStream));
-		}
-		finally {
-			inputStream.close();
+	protected void writeToArchive(ZipEntry entry, EntryWriter entryWriter) throws IOException {
+		this.jarOutputStream.putArchiveEntry(asJarArchiveEntry(entry));
+		if (entryWriter != null) {
+			entryWriter.write(this.jarOutputStream);
 		}
+		this.jarOutputStream.closeArchiveEntry();
 	}
 
-	/**
-	 * Write a nested library.
-	 * @param destination the destination of the library
-	 * @param library the library
-	 * @throws IOException if the write fails
-	 */
-	public void writeNestedLibrary(String destination, Library library) throws IOException {
-		File file = library.getFile();
-		JarArchiveEntry entry = new JarArchiveEntry(destination + library.getName());
-		entry.setTime(getNestedLibraryTime(file));
-		new CrcAndSize(file).setupStoredEntry(entry);
-		try (FileInputStream input = new FileInputStream(file)) {
-			writeEntry(entry, new InputStreamEntryWriter(input), new LibraryUnpackHandler(library));
-		}
-	}
-
-	/**
-	 * Write a simple index file containing the specified UTF-8 lines.
-	 * @param location the location of the index file
-	 * @param lines the lines to write
-	 * @throws IOException if the write fails
-	 * @since 2.3.0
-	 */
-	public void writeIndexFile(String location, List<String> lines) throws IOException {
-		if (location != null) {
-			JarArchiveEntry entry = new JarArchiveEntry(location);
-			writeEntry(entry, (outputStream) -> {
-				BufferedWriter writer = new BufferedWriter(
-						new OutputStreamWriter(outputStream, StandardCharsets.UTF_8));
-				for (String line : lines) {
-					writer.write(line);
-					writer.write("\n");
-				}
-				writer.flush();
-			});
-		}
-	}
-
-	private long getNestedLibraryTime(File file) {
-		try {
-			try (JarFile jarFile = new JarFile(file)) {
-				Enumeration<JarEntry> entries = jarFile.entries();
-				while (entries.hasMoreElements()) {
-					JarEntry entry = entries.nextElement();
-					if (!entry.isDirectory()) {
-						return entry.getTime();
-					}
-				}
-			}
-		}
-		catch (Exception ex) {
-			// Ignore and just use the source file timestamp
-		}
-		return file.lastModified();
-	}
-
-	/**
-	 * Write the required spring-boot-loader classes to the JAR.
-	 * @throws IOException if the classes cannot be written
-	 */
-	@Override
-	public void writeLoaderClasses() throws IOException {
-		writeLoaderClasses(NESTED_LOADER_JAR);
-	}
-
-	/**
-	 * Write the required spring-boot-loader classes to the JAR.
-	 * @param loaderJarResourceName the name of the resource containing the loader classes
-	 * to be written
-	 * @throws IOException if the classes cannot be written
-	 */
-	@Override
-	public void writeLoaderClasses(String loaderJarResourceName) throws IOException {
-		URL loaderJar = getClass().getClassLoader().getResource(loaderJarResourceName);
-		try (JarInputStream inputStream = new JarInputStream(new BufferedInputStream(loaderJar.openStream()))) {
-			JarEntry entry;
-			while ((entry = inputStream.getNextJarEntry()) != null) {
-				if (entry.getName().endsWith(".class")) {
-					writeEntry(new JarArchiveEntry(entry), new InputStreamEntryWriter(inputStream));
-				}
-			}
+	private JarArchiveEntry asJarArchiveEntry(ZipEntry entry) throws ZipException {
+		if (entry instanceof JarArchiveEntry) {
+			return (JarArchiveEntry) entry;
 		}
+		return new JarArchiveEntry(entry);
 	}
 
 	/**
@@ -269,264 +105,7 @@ public class JarWriter implements LoaderClassesWriter, AutoCloseable {
 	 */
 	@Override
 	public void close() throws IOException {
-		this.jarOutput.close();
-	}
-
-	private void writeEntry(JarArchiveEntry entry, EntryWriter entryWriter) throws IOException {
-		writeEntry(entry, entryWriter, UnpackHandler.NEVER);
-	}
-
-	/**
-	 * Perform the actual write of a {@link JarEntry}. All other write methods delegate to
-	 * this one.
-	 * @param entry the entry to write
-	 * @param entryWriter the entry writer or {@code null} if there is no content
-	 * @param unpackHandler handles possible unpacking for the entry
-	 * @throws IOException in case of I/O errors
-	 */
-	private void writeEntry(JarArchiveEntry entry, EntryWriter entryWriter, UnpackHandler unpackHandler)
-			throws IOException {
-		String name = entry.getName();
-		writeParentFolderEntries(name);
-		if (this.writtenEntries.add(name)) {
-			entry.setUnixMode(name.endsWith("/") ? UNIX_DIR_MODE : UNIX_FILE_MODE);
-			entryWriter = addUnpackCommentIfNecessary(entry, entryWriter, unpackHandler);
-			this.jarOutput.putArchiveEntry(entry);
-			if (entryWriter != null) {
-				entryWriter.write(this.jarOutput);
-			}
-			this.jarOutput.closeArchiveEntry();
-		}
-	}
-
-	private void writeParentFolderEntries(String name) throws IOException {
-		String parent = name.endsWith("/") ? name.substring(0, name.length() - 1) : name;
-		while (parent.lastIndexOf('/') != -1) {
-			parent = parent.substring(0, parent.lastIndexOf('/'));
-			if (!parent.isEmpty()) {
-				writeEntry(new JarArchiveEntry(parent + "/"), null, UnpackHandler.NEVER);
-			}
-		}
-	}
-
-	private EntryWriter addUnpackCommentIfNecessary(JarArchiveEntry entry, EntryWriter entryWriter,
-			UnpackHandler unpackHandler) throws IOException {
-		if (entryWriter == null || !unpackHandler.requiresUnpack(entry.getName())) {
-			return entryWriter;
-		}
-		ByteArrayOutputStream output = new ByteArrayOutputStream();
-		entryWriter.write(output);
-		entry.setComment("UNPACK:" + unpackHandler.sha1Hash(entry.getName()));
-		return new InputStreamEntryWriter(new ByteArrayInputStream(output.toByteArray()));
-	}
-
-	/**
-	 * Interface used to write jar entry date.
-	 */
-	private interface EntryWriter {
-
-		/**
-		 * Write entry data to the specified output stream.
-		 * @param outputStream the destination for the data
-		 * @throws IOException in case of I/O errors
-		 */
-		void write(OutputStream outputStream) throws IOException;
-
-	}
-
-	/**
-	 * {@link EntryWriter} that writes content from an {@link InputStream}.
-	 */
-	private static class InputStreamEntryWriter implements EntryWriter {
-
-		private final InputStream inputStream;
-
-		InputStreamEntryWriter(InputStream inputStream) {
-			this.inputStream = inputStream;
-		}
-
-		@Override
-		public void write(OutputStream outputStream) throws IOException {
-			byte[] buffer = new byte[BUFFER_SIZE];
-			int bytesRead;
-			while ((bytesRead = this.inputStream.read(buffer)) != -1) {
-				outputStream.write(buffer, 0, bytesRead);
-			}
-			outputStream.flush();
-		}
-
-	}
-
-	/**
-	 * {@link InputStream} that can peek ahead at zip header bytes.
-	 */
-	static class ZipHeaderPeekInputStream extends FilterInputStream {
-
-		private static final byte[] ZIP_HEADER = new byte[] { 0x50, 0x4b, 0x03, 0x04 };
-
-		private final byte[] header;
-
-		private final int headerLength;
-
-		private int position;
-
-		private ByteArrayInputStream headerStream;
-
-		protected ZipHeaderPeekInputStream(InputStream in) throws IOException {
-			super(in);
-			this.header = new byte[4];
-			this.headerLength = in.read(this.header);
-			this.headerStream = new ByteArrayInputStream(this.header, 0, this.headerLength);
-		}
-
-		@Override
-		public int read() throws IOException {
-			int read = (this.headerStream != null) ? this.headerStream.read() : -1;
-			if (read != -1) {
-				this.position++;
-				if (this.position >= this.headerLength) {
-					this.headerStream = null;
-				}
-				return read;
-			}
-			return super.read();
-		}
-
-		@Override
-		public int read(byte[] b) throws IOException {
-			return read(b, 0, b.length);
-		}
-
-		@Override
-		public int read(byte[] b, int off, int len) throws IOException {
-			int read = (this.headerStream != null) ? this.headerStream.read(b, off, len) : -1;
-			if (read <= 0) {
-				return readRemainder(b, off, len);
-			}
-			this.position += read;
-			if (read < len) {
-				int remainderRead = readRemainder(b, off + read, len - read);
-				if (remainderRead > 0) {
-					read += remainderRead;
-				}
-			}
-			if (this.position >= this.headerLength) {
-				this.headerStream = null;
-			}
-			return read;
-		}
-
-		boolean hasZipHeader() {
-			return Arrays.equals(this.header, ZIP_HEADER);
-		}
-
-		private int readRemainder(byte[] b, int off, int len) throws IOException {
-			int read = super.read(b, off, len);
-			if (read > 0) {
-				this.position += read;
-			}
-			return read;
-		}
-
-	}
-
-	/**
-	 * Data holder for CRC and Size.
-	 */
-	private static class CrcAndSize {
-
-		private final CRC32 crc = new CRC32();
-
-		private long size;
-
-		CrcAndSize(File file) throws IOException {
-			try (FileInputStream inputStream = new FileInputStream(file)) {
-				load(inputStream);
-			}
-		}
-
-		CrcAndSize(InputStream inputStream) throws IOException {
-			load(inputStream);
-		}
-
-		private void load(InputStream inputStream) throws IOException {
-			byte[] buffer = new byte[BUFFER_SIZE];
-			int bytesRead;
-			while ((bytesRead = inputStream.read(buffer)) != -1) {
-				this.crc.update(buffer, 0, bytesRead);
-				this.size += bytesRead;
-			}
-		}
-
-		void setupStoredEntry(JarArchiveEntry entry) {
-			entry.setSize(this.size);
-			entry.setCompressedSize(this.size);
-			entry.setCrc(this.crc.getValue());
-			entry.setMethod(ZipEntry.STORED);
-		}
-
-	}
-
-	/**
-	 * An {@code EntryTransformer} enables the transformation of {@link JarEntry jar
-	 * entries} during the writing process.
-	 */
-	@FunctionalInterface
-	interface EntryTransformer {
-
-		/**
-		 * No-op entity transformer.
-		 */
-		EntryTransformer NONE = (jarEntry) -> jarEntry;
-
-		JarArchiveEntry transform(JarArchiveEntry jarEntry);
-
-	}
-
-	/**
-	 * An {@code UnpackHandler} determines whether or not unpacking is required and
-	 * provides a SHA1 hash if required.
-	 */
-	interface UnpackHandler {
-
-		UnpackHandler NEVER = new UnpackHandler() {
-
-			@Override
-			public boolean requiresUnpack(String name) {
-				return false;
-			}
-
-			@Override
-			public String sha1Hash(String name) throws IOException {
-				throw new UnsupportedOperationException();
-			}
-
-		};
-
-		boolean requiresUnpack(String name);
-
-		String sha1Hash(String name) throws IOException;
-
-	}
-
-	private static final class LibraryUnpackHandler implements UnpackHandler {
-
-		private final Library library;
-
-		private LibraryUnpackHandler(Library library) {
-			this.library = library;
-		}
-
-		@Override
-		public boolean requiresUnpack(String name) {
-			return this.library.isUnpackRequired();
-		}
-
-		@Override
-		public String sha1Hash(String name) throws IOException {
-			return FileUtils.sha1Hash(this.library.getFile());
-		}
-
+		this.jarOutputStream.close();
 	}
 
 }

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Packager.java

@@ -0,0 +1,468 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Map.Entry;
+import java.util.concurrent.TimeUnit;
+import java.util.jar.Attributes;
+import java.util.jar.JarFile;
+import java.util.jar.Manifest;
+
+import org.apache.commons.compress.archivers.jar.JarArchiveEntry;
+
+import org.springframework.boot.loader.tools.AbstractJarWriter.EntryTransformer;
+import org.springframework.boot.loader.tools.AbstractJarWriter.UnpackHandler;
+import org.springframework.core.io.support.SpringFactoriesLoader;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Abstract base class for packagers.
+ *
+ * @author Phillip Webb
+ * @author Andy Wilkinson
+ * @author Stephane Nicoll
+ * @author Madhura Bhave
+ * @since 2.3.0
+ */
+public abstract class Packager {
+
+	private static final String MAIN_CLASS_ATTRIBUTE = "Main-Class";
+
+	private static final String START_CLASS_ATTRIBUTE = "Start-Class";
+
+	private static final String BOOT_VERSION_ATTRIBUTE = "Spring-Boot-Version";
+
+	private static final String BOOT_CLASSES_ATTRIBUTE = "Spring-Boot-Classes";
+
+	private static final String BOOT_LIB_ATTRIBUTE = "Spring-Boot-Lib";
+
+	private static final String BOOT_CLASSPATH_INDEX_ATTRIBUTE = "Spring-Boot-Classpath-Index";
+
+	private static final String BOOT_LAYERS_INDEX_ATTRIBUTE = "Spring-Boot-Layers-Index";
+
+	private static final byte[] ZIP_FILE_HEADER = new byte[] { 'P', 'K', 3, 4 };
+
+	private static final long FIND_WARNING_TIMEOUT = TimeUnit.SECONDS.toMillis(10);
+
+	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
+
+	private List<MainClassTimeoutWarningListener> mainClassTimeoutListeners = new ArrayList<>();
+
+	private String mainClass;
+
+	private final File source;
+
+	private Layout layout;
+
+	private LayoutFactory layoutFactory;
+
+	private Layers layers = Layers.IMPLICIT;
+
+	/**
+	 * Create a new {@link Packager} instance.
+	 * @param source the source JAR file to package
+	 * @param layoutFactory the layout factory to use or {@code null}
+	 */
+	protected Packager(File source, LayoutFactory layoutFactory) {
+		Assert.notNull(source, "Source file must not be null");
+		Assert.isTrue(source.exists() && source.isFile(),
+				"Source must refer to an existing file, got " + source.getAbsolutePath());
+		this.source = source.getAbsoluteFile();
+		this.layoutFactory = layoutFactory;
+	}
+
+	/**
+	 * Add a listener that will be triggered to display a warning if searching for the
+	 * main class takes too long.
+	 * @param listener the listener to add
+	 */
+	public void addMainClassTimeoutWarningListener(MainClassTimeoutWarningListener listener) {
+		this.mainClassTimeoutListeners.add(listener);
+	}
+
+	/**
+	 * Sets the main class that should be run. If not specified the value from the
+	 * MANIFEST will be used, or if no manifest entry is found the archive will be
+	 * searched for a suitable class.
+	 * @param mainClass the main class name
+	 */
+	public void setMainClass(String mainClass) {
+		this.mainClass = mainClass;
+	}
+
+	/**
+	 * Sets the layout to use for the jar. Defaults to {@link Layouts#forFile(File)}.
+	 * @param layout the layout
+	 */
+	public void setLayout(Layout layout) {
+		Assert.notNull(layout, "Layout must not be null");
+		this.layout = layout;
+	}
+
+	/**
+	 * Sets the layout factory for the jar. The factory can be used when no specific
+	 * layout is specified.
+	 * @param layoutFactory the layout factory to set
+	 */
+	public void setLayoutFactory(LayoutFactory layoutFactory) {
+		this.layoutFactory = layoutFactory;
+	}
+
+	/**
+	 * Sets the layers that should be used in the jar.
+	 * @param layers the jar layers
+	 * @see LayeredLayout
+	 */
+	public void setLayers(Layers layers) {
+		Assert.notNull(layers, "Layers must not be null");
+		this.layers = layers;
+	}
+
+	protected final boolean isAlreadyPackaged() throws IOException {
+		return isAlreadyPackaged(this.source);
+	}
+
+	protected final boolean isAlreadyPackaged(File file) throws IOException {
+		try (JarFile jarFile = new JarFile(file)) {
+			Manifest manifest = jarFile.getManifest();
+			return (manifest != null && manifest.getMainAttributes().getValue(BOOT_VERSION_ATTRIBUTE) != null);
+		}
+	}
+
+	protected final void write(JarFile sourceJar, Libraries libraries, AbstractJarWriter writer) throws IOException {
+		Assert.notNull(libraries, "Libraries must not be null");
+		WritableLibraries writeableLibraries = new WritableLibraries(libraries);
+		writer.writeManifest(buildManifest(sourceJar));
+		writeLoaderClasses(writer);
+		writer.writeEntries(sourceJar, getEntityTransformer(), writeableLibraries);
+		writeableLibraries.write(writer);
+	}
+
+	private void writeLoaderClasses(AbstractJarWriter writer) throws IOException {
+		Layout layout = getLayout();
+		if (layout instanceof CustomLoaderLayout) {
+			((CustomLoaderLayout) getLayout()).writeLoadedClasses(writer);
+		}
+		else if (layout.isExecutable()) {
+			writer.writeLoaderClasses();
+		}
+	}
+
+	private EntryTransformer getEntityTransformer() {
+		if (getLayout() instanceof RepackagingLayout) {
+			return new RepackagingEntryTransformer((RepackagingLayout) getLayout(), this.layers);
+		}
+		return EntryTransformer.NONE;
+	}
+
+	private boolean isZip(File file) {
+		try {
+			try (FileInputStream inputStream = new FileInputStream(file)) {
+				return isZip(inputStream);
+			}
+		}
+		catch (IOException ex) {
+			return false;
+		}
+	}
+
+	private boolean isZip(InputStream inputStream) throws IOException {
+		for (byte magicByte : ZIP_FILE_HEADER) {
+			if (inputStream.read() != magicByte) {
+				return false;
+			}
+		}
+		return true;
+	}
+
+	private Manifest buildManifest(JarFile source) throws IOException {
+		Manifest manifest = createInitialManifest(source);
+		addMainAndStartAttributes(source, manifest);
+		addBootAttributes(manifest.getMainAttributes());
+		return manifest;
+	}
+
+	private Manifest createInitialManifest(JarFile source) throws IOException {
+		if (source.getManifest() != null) {
+			return new Manifest(source.getManifest());
+		}
+		Manifest manifest = new Manifest();
+		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");
+		return manifest;
+	}
+
+	private void addMainAndStartAttributes(JarFile source, Manifest manifest) throws IOException {
+		String mainClass = getMainClass(source, manifest);
+		String launcherClass = getLayout().getLauncherClassName();
+		if (launcherClass != null) {
+			Assert.state(mainClass != null, "Unable to find main class");
+			manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE, launcherClass);
+			manifest.getMainAttributes().putValue(START_CLASS_ATTRIBUTE, mainClass);
+		}
+		else if (mainClass != null) {
+			manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE, mainClass);
+		}
+	}
+
+	private String getMainClass(JarFile source, Manifest manifest) throws IOException {
+		if (this.mainClass != null) {
+			return this.mainClass;
+		}
+		String attributeValue = manifest.getMainAttributes().getValue(MAIN_CLASS_ATTRIBUTE);
+		if (attributeValue != null) {
+			return attributeValue;
+		}
+		return findMainMethodWithTimeoutWarning(source);
+	}
+
+	private String findMainMethodWithTimeoutWarning(JarFile source) throws IOException {
+		long startTime = System.currentTimeMillis();
+		String mainMethod = findMainMethod(source);
+		long duration = System.currentTimeMillis() - startTime;
+		if (duration > FIND_WARNING_TIMEOUT) {
+			for (MainClassTimeoutWarningListener listener : this.mainClassTimeoutListeners) {
+				listener.handleTimeoutWarning(duration, mainMethod);
+			}
+		}
+		return mainMethod;
+	}
+
+	protected String findMainMethod(JarFile source) throws IOException {
+		return MainClassFinder.findSingleMainClass(source, getLayout().getClassesLocation(),
+				SPRING_BOOT_APPLICATION_CLASS_NAME);
+	}
+
+	/**
+	 * Return the {@link File} to use to backup the original source.
+	 * @return the file to use to backup the original source
+	 */
+	public final File getBackupFile() {
+		File source = getSource();
+		return new File(source.getParentFile(), source.getName() + ".original");
+	}
+
+	protected final File getSource() {
+		return this.source;
+	}
+
+	protected final Layout getLayout() {
+		if (this.layout == null) {
+			Layout createdLayout = getLayoutFactory().getLayout(this.source);
+			Assert.state(createdLayout != null, "Unable to detect layout");
+			this.layout = createdLayout;
+		}
+		return this.layout;
+	}
+
+	private LayoutFactory getLayoutFactory() {
+		if (this.layoutFactory != null) {
+			return this.layoutFactory;
+		}
+		List<LayoutFactory> factories = SpringFactoriesLoader.loadFactories(LayoutFactory.class, null);
+		if (factories.isEmpty()) {
+			return new DefaultLayoutFactory();
+		}
+		Assert.state(factories.size() == 1, "No unique LayoutFactory found");
+		return factories.get(0);
+	}
+
+	private void addBootAttributes(Attributes attributes) {
+		attributes.putValue(BOOT_VERSION_ATTRIBUTE, getClass().getPackage().getImplementationVersion());
+		Layout layout = getLayout();
+		if (layout instanceof LayeredLayout) {
+			addBootBootAttributesForLayeredLayout(attributes, (LayeredLayout) layout);
+		}
+		else if (layout instanceof RepackagingLayout) {
+			addBootBootAttributesForRepackagingLayout(attributes, (RepackagingLayout) layout);
+		}
+		else {
+			addBootBootAttributesForPlainLayout(attributes, layout);
+		}
+	}
+
+	private void addBootBootAttributesForLayeredLayout(Attributes attributes, LayeredLayout layout) {
+		String layersIndexFileLocation = layout.getLayersIndexFileLocation();
+		putIfHasLength(attributes, BOOT_LAYERS_INDEX_ATTRIBUTE, layersIndexFileLocation);
+		putIfHasLength(attributes, BOOT_CLASSPATH_INDEX_ATTRIBUTE, layout.getClasspathIndexFileLocation());
+	}
+
+	private void addBootBootAttributesForRepackagingLayout(Attributes attributes, RepackagingLayout layout) {
+		attributes.putValue(BOOT_CLASSES_ATTRIBUTE, layout.getRepackagedClassesLocation());
+		putIfHasLength(attributes, BOOT_LIB_ATTRIBUTE, getLayout().getLibraryLocation("", LibraryScope.COMPILE));
+		putIfHasLength(attributes, BOOT_CLASSPATH_INDEX_ATTRIBUTE, layout.getClasspathIndexFileLocation());
+	}
+
+	private void addBootBootAttributesForPlainLayout(Attributes attributes, Layout layout) {
+		attributes.putValue(BOOT_CLASSES_ATTRIBUTE, getLayout().getClassesLocation());
+		putIfHasLength(attributes, BOOT_LIB_ATTRIBUTE, getLayout().getLibraryLocation("", LibraryScope.COMPILE));
+	}
+
+	private void putIfHasLength(Attributes attributes, String name, String value) {
+		if (StringUtils.hasLength(value)) {
+			attributes.putValue(name, value);
+		}
+	}
+
+	/**
+	 * Callback interface used to present a warning when finding the main class takes too
+	 * long.
+	 */
+	@FunctionalInterface
+	public interface MainClassTimeoutWarningListener {
+
+		/**
+		 * Handle a timeout warning.
+		 * @param duration the amount of time it took to find the main method
+		 * @param mainMethod the main method that was actually found
+		 */
+		void handleTimeoutWarning(long duration, String mainMethod);
+
+	}
+
+	/**
+	 * An {@code EntryTransformer} that renames entries by applying a prefix.
+	 */
+	private static final class RepackagingEntryTransformer implements EntryTransformer {
+
+		private final RepackagingLayout layout;
+
+		private final Layers layers;
+
+		private RepackagingEntryTransformer(RepackagingLayout layout, Layers layers) {
+			this.layout = layout;
+			this.layers = layers;
+		}
+
+		@Override
+		public JarArchiveEntry transform(JarArchiveEntry entry) {
+			if (entry.getName().equals("META-INF/INDEX.LIST")) {
+				return null;
+			}
+			if (!isTransformable(entry)) {
+				return entry;
+			}
+			String transformedName = transformName(entry.getName());
+			JarArchiveEntry transformedEntry = new JarArchiveEntry(transformedName);
+			transformedEntry.setTime(entry.getTime());
+			transformedEntry.setSize(entry.getSize());
+			transformedEntry.setMethod(entry.getMethod());
+			if (entry.getComment() != null) {
+				transformedEntry.setComment(entry.getComment());
+			}
+			transformedEntry.setCompressedSize(entry.getCompressedSize());
+			transformedEntry.setCrc(entry.getCrc());
+			if (entry.getCreationTime() != null) {
+				transformedEntry.setCreationTime(entry.getCreationTime());
+			}
+			if (entry.getExtra() != null) {
+				transformedEntry.setExtra(entry.getExtra());
+			}
+			if (entry.getLastAccessTime() != null) {
+				transformedEntry.setLastAccessTime(entry.getLastAccessTime());
+			}
+			if (entry.getLastModifiedTime() != null) {
+				transformedEntry.setLastModifiedTime(entry.getLastModifiedTime());
+			}
+			return transformedEntry;
+		}
+
+		private String transformName(String name) {
+			if (this.layout instanceof LayeredLayout) {
+				Layer layer = this.layers.getLayer(name);
+				Assert.state(layer != null, "Invalid 'null' layer from " + this.layers.getClass().getName());
+				return ((LayeredLayout) this.layout).getRepackagedClassesLocation(layer) + name;
+			}
+			return this.layout.getRepackagedClassesLocation() + name;
+		}
+
+		private boolean isTransformable(JarArchiveEntry entry) {
+			String name = entry.getName();
+			if (name.startsWith("META-INF/")) {
+				return name.equals("META-INF/aop.xml") || name.endsWith(".kotlin_module");
+			}
+			return !name.startsWith("BOOT-INF/") && !name.equals("module-info.class");
+		}
+
+	}
+
+	/**
+	 * An {@link UnpackHandler} that determines that an entry needs to be unpacked if a
+	 * library that requires unpacking has a matching entry name.
+	 */
+	private final class WritableLibraries implements UnpackHandler {
+
+		private final Map<String, Library> libraryEntryNames = new LinkedHashMap<>();
+
+		WritableLibraries(Libraries libraries) throws IOException {
+			libraries.doWithLibraries((library) -> {
+				if (isZip(library.getFile())) {
+					String location = getLocation(library);
+					if (location != null) {
+						Library existing = this.libraryEntryNames.putIfAbsent(location + library.getName(), library);
+						Assert.state(existing == null, "Duplicate library " + library.getName());
+					}
+				}
+			});
+		}
+
+		private String getLocation(Library library) {
+			Layout layout = getLayout();
+			if (layout instanceof LayeredLayout) {
+				Layers layers = Packager.this.layers;
+				Layer layer = layers.getLayer(library);
+				Assert.state(layer != null, "Invalid 'null' library layer from " + layers.getClass().getName());
+				return ((LayeredLayout) layout).getLibraryLocation(library.getName(), library.getScope(), layer);
+			}
+			return layout.getLibraryLocation(library.getName(), library.getScope());
+		}
+
+		@Override
+		public boolean requiresUnpack(String name) {
+			Library library = this.libraryEntryNames.get(name);
+			return library != null && library.isUnpackRequired();
+		}
+
+		@Override
+		public String sha1Hash(String name) throws IOException {
+			Library library = this.libraryEntryNames.get(name);
+			Assert.notNull(library, "No library found for entry name '" + name + "'");
+			return FileUtils.sha1Hash(library.getFile());
+		}
+
+		private void write(AbstractJarWriter writer) throws IOException {
+			for (Entry<String, Library> entry : this.libraryEntryNames.entrySet()) {
+				writer.writeNestedLibrary(entry.getKey().substring(0, entry.getKey().lastIndexOf('/') + 1),
+						entry.getValue());
+			}
+			if (getLayout() instanceof RepackagingLayout) {
+				String location = ((RepackagingLayout) getLayout()).getClasspathIndexFileLocation();
+				writer.writeIndexFile(location, new ArrayList<>(this.libraryEntryNames.keySet()));
+			}
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/Repackager.java

@@ -17,26 +17,10 @@
 package org.springframework.boot.loader.tools;
 
 import java.io.File;
-import java.io.FileInputStream;
 import java.io.IOException;
-import java.io.InputStream;
-import java.util.ArrayList;
-import java.util.LinkedHashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.Map.Entry;
-import java.util.concurrent.TimeUnit;
-import java.util.jar.Attributes;
 import java.util.jar.JarFile;
-import java.util.jar.Manifest;
 
-import org.apache.commons.compress.archivers.jar.JarArchiveEntry;
-
-import org.springframework.boot.loader.tools.JarWriter.EntryTransformer;
-import org.springframework.boot.loader.tools.JarWriter.UnpackHandler;
-import org.springframework.core.io.support.SpringFactoriesLoader;
 import org.springframework.util.Assert;
-import org.springframework.util.StringUtils;
 
 /**
  * Utility class that can be used to repackage an archive so that it can be executed using
@@ -48,71 +32,16 @@ import org.springframework.util.StringUtils;
  * @author Madhura Bhave
  * @since 1.0.0
  */
-public class Repackager {
-
-	private static final String MAIN_CLASS_ATTRIBUTE = "Main-Class";
-
-	private static final String START_CLASS_ATTRIBUTE = "Start-Class";
-
-	private static final String BOOT_VERSION_ATTRIBUTE = "Spring-Boot-Version";
-
-	private static final String BOOT_CLASSES_ATTRIBUTE = "Spring-Boot-Classes";
-
-	private static final String BOOT_LIB_ATTRIBUTE = "Spring-Boot-Lib";
-
-	private static final String BOOT_CLASSPATH_INDEX_ATTRIBUTE = "Spring-Boot-Classpath-Index";
-
-	private static final String BOOT_LAYERS_INDEX_ATTRIBUTE = "Spring-Boot-Layers-Index";
-
-	private static final byte[] ZIP_FILE_HEADER = new byte[] { 'P', 'K', 3, 4 };
-
-	private static final long FIND_WARNING_TIMEOUT = TimeUnit.SECONDS.toMillis(10);
-
-	private static final String SPRING_BOOT_APPLICATION_CLASS_NAME = "org.springframework.boot.autoconfigure.SpringBootApplication";
-
-	private List<MainClassTimeoutWarningListener> mainClassTimeoutListeners = new ArrayList<>();
-
-	private String mainClass;
+public class Repackager extends Packager {
 
 	private boolean backupSource = true;
 
-	private final File source;
-
-	private Layout layout;
-
-	private LayoutFactory layoutFactory;
-
-	private Layers layers = Layers.IMPLICIT;
-
 	public Repackager(File source) {
 		this(source, null);
 	}
 
 	public Repackager(File source, LayoutFactory layoutFactory) {
-		Assert.notNull(source, "Source file must be provided");
-		Assert.isTrue(source.exists() && source.isFile(),
-				"Source must refer to an existing file, got " + source.getAbsolutePath());
-		this.source = source.getAbsoluteFile();
-		this.layoutFactory = layoutFactory;
-	}
-
-	/**
-	 * Add a listener that will be triggered to display a warning if searching for the
-	 * main class takes too long.
-	 * @param listener the listener to add
-	 */
-	public void addMainClassTimeoutWarningListener(MainClassTimeoutWarningListener listener) {
-		this.mainClassTimeoutListeners.add(listener);
-	}
-
-	/**
-	 * Sets the main class that should be run. If not specified the value from the
-	 * MANIFEST will be used, or if no manifest entry is found the archive will be
-	 * searched for a suitable class.
-	 * @param mainClass the main class name
-	 */
-	public void setMainClass(String mainClass) {
-		this.mainClass = mainClass;
+		super(source, layoutFactory);
 	}
 
 	/**
@@ -123,41 +52,13 @@ public class Repackager {
 		this.backupSource = backupSource;
 	}
 
-	/**
-	 * Sets the layout to use for the jar. Defaults to {@link Layouts#forFile(File)}.
-	 * @param layout the layout
-	 */
-	public void setLayout(Layout layout) {
-		Assert.notNull(layout, "Layout must not be null");
-		this.layout = layout;
-	}
-
-	/**
-	 * Sets the layers that should be used in the jar.
-	 * @param layers the jar layers
-	 * @see LayeredLayout
-	 */
-	public void setLayers(Layers layers) {
-		Assert.notNull(layers, "Layers must not be null");
-		this.layers = layers;
-	}
-
-	/**
-	 * Sets the layout factory for the jar. The factory can be used when no specific
-	 * layout is specified.
-	 * @param layoutFactory the layout factory to set
-	 */
-	public void setLayoutFactory(LayoutFactory layoutFactory) {
-		this.layoutFactory = layoutFactory;
-	}
-
 	/**
 	 * Repackage the source file so that it can be run using '{@literal java -jar}'.
 	 * @param libraries the libraries required to run the archive
 	 * @throws IOException if the file cannot be repackaged
 	 */
 	public void repackage(Libraries libraries) throws IOException {
-		repackage(this.source, libraries);
+		repackage(getSource(), libraries);
 	}
 
 	/**
@@ -182,197 +83,34 @@ public class Repackager {
 	 */
 	public void repackage(File destination, Libraries libraries, LaunchScript launchScript) throws IOException {
 		Assert.isTrue(destination != null && !destination.isDirectory(), "Invalid destination");
-		Assert.notNull(libraries, "Libraries must not be null");
-		if (this.layout == null) {
-			this.layout = getLayoutFactory().getLayout(this.source);
-		}
 		destination = destination.getAbsoluteFile();
-		File workingSource = this.source;
-		if (alreadyRepackaged() && this.source.equals(destination)) {
+		File source = getSource();
+		if (isAlreadyPackaged() && source.equals(destination)) {
 			return;
 		}
-		if (this.source.equals(destination)) {
+		File workingSource = source;
+		if (source.equals(destination)) {
 			workingSource = getBackupFile();
 			workingSource.delete();
-			renameFile(this.source, workingSource);
+			renameFile(source, workingSource);
 		}
 		destination.delete();
 		try {
-			try (JarFile jarFileSource = new JarFile(workingSource)) {
-				repackage(jarFileSource, destination, libraries, launchScript);
+			try (JarFile sourceJar = new JarFile(workingSource)) {
+				repackage(sourceJar, destination, libraries, launchScript);
 			}
 		}
 		finally {
-			if (!this.backupSource && !this.source.equals(workingSource)) {
+			if (!this.backupSource && !source.equals(workingSource)) {
 				deleteFile(workingSource);
 			}
 		}
 	}
 
-	private LayoutFactory getLayoutFactory() {
-		if (this.layoutFactory != null) {
-			return this.layoutFactory;
-		}
-		List<LayoutFactory> factories = SpringFactoriesLoader.loadFactories(LayoutFactory.class, null);
-		if (factories.isEmpty()) {
-			return new DefaultLayoutFactory();
-		}
-		Assert.state(factories.size() == 1, "No unique LayoutFactory found");
-		return factories.get(0);
-	}
-
-	/**
-	 * Return the {@link File} to use to backup the original source.
-	 * @return the file to use to backup the original source
-	 */
-	public final File getBackupFile() {
-		return new File(this.source.getParentFile(), this.source.getName() + ".original");
-	}
-
-	private boolean alreadyRepackaged() throws IOException {
-		try (JarFile jarFile = new JarFile(this.source)) {
-			Manifest manifest = jarFile.getManifest();
-			return (manifest != null && manifest.getMainAttributes().getValue(BOOT_VERSION_ATTRIBUTE) != null);
-		}
-	}
-
 	private void repackage(JarFile sourceJar, File destination, Libraries libraries, LaunchScript launchScript)
 			throws IOException {
-		WritableLibraries writeableLibraries = new WritableLibraries(libraries);
 		try (JarWriter writer = new JarWriter(destination, launchScript)) {
-			writer.writeManifest(buildManifest(sourceJar));
-			writeLoaderClasses(writer);
-			writer.writeEntries(sourceJar, getEntityTransformer(), writeableLibraries);
-			writeableLibraries.write(writer);
-		}
-	}
-
-	private void writeLoaderClasses(JarWriter writer) throws IOException {
-		if (this.layout instanceof CustomLoaderLayout) {
-			((CustomLoaderLayout) this.layout).writeLoadedClasses(writer);
-		}
-		else if (this.layout.isExecutable()) {
-			writer.writeLoaderClasses();
-		}
-	}
-
-	private EntryTransformer getEntityTransformer() {
-		if (this.layout instanceof RepackagingLayout) {
-			return new RepackagingEntryTransformer((RepackagingLayout) this.layout, this.layers);
-		}
-		return EntryTransformer.NONE;
-	}
-
-	private boolean isZip(File file) {
-		try {
-			try (FileInputStream fileInputStream = new FileInputStream(file)) {
-				return isZip(fileInputStream);
-			}
-		}
-		catch (IOException ex) {
-			return false;
-		}
-	}
-
-	private boolean isZip(InputStream inputStream) throws IOException {
-		for (byte magicByte : ZIP_FILE_HEADER) {
-			if (inputStream.read() != magicByte) {
-				return false;
-			}
-		}
-		return true;
-	}
-
-	private Manifest buildManifest(JarFile source) throws IOException {
-		Manifest manifest = createInitialManifest(source);
-		addMainAndStartAttributes(source, manifest);
-		addBootAttributes(manifest.getMainAttributes());
-		return manifest;
-	}
-
-	private Manifest createInitialManifest(JarFile source) throws IOException {
-		if (source.getManifest() != null) {
-			return new Manifest(source.getManifest());
-		}
-		Manifest manifest = new Manifest();
-		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");
-		return manifest;
-	}
-
-	private void addMainAndStartAttributes(JarFile source, Manifest manifest) throws IOException {
-		String mainClass = getMainClass(source, manifest);
-		String launcherClass = this.layout.getLauncherClassName();
-		if (launcherClass != null) {
-			Assert.state(mainClass != null, "Unable to find main class");
-			manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE, launcherClass);
-			manifest.getMainAttributes().putValue(START_CLASS_ATTRIBUTE, mainClass);
-		}
-		else if (mainClass != null) {
-			manifest.getMainAttributes().putValue(MAIN_CLASS_ATTRIBUTE, mainClass);
-		}
-	}
-
-	private String getMainClass(JarFile source, Manifest manifest) throws IOException {
-		if (this.mainClass != null) {
-			return this.mainClass;
-		}
-		String attributeValue = manifest.getMainAttributes().getValue(MAIN_CLASS_ATTRIBUTE);
-		if (attributeValue != null) {
-			return attributeValue;
-		}
-		return findMainMethodWithTimeoutWarning(source);
-	}
-
-	private String findMainMethodWithTimeoutWarning(JarFile source) throws IOException {
-		long startTime = System.currentTimeMillis();
-		String mainMethod = findMainMethod(source);
-		long duration = System.currentTimeMillis() - startTime;
-		if (duration > FIND_WARNING_TIMEOUT) {
-			for (MainClassTimeoutWarningListener listener : this.mainClassTimeoutListeners) {
-				listener.handleTimeoutWarning(duration, mainMethod);
-			}
-		}
-		return mainMethod;
-	}
-
-	protected String findMainMethod(JarFile source) throws IOException {
-		return MainClassFinder.findSingleMainClass(source, this.layout.getClassesLocation(),
-				SPRING_BOOT_APPLICATION_CLASS_NAME);
-	}
-
-	private void addBootAttributes(Attributes attributes) {
-		attributes.putValue(BOOT_VERSION_ATTRIBUTE, getClass().getPackage().getImplementationVersion());
-		if (this.layout instanceof LayeredLayout) {
-			addBootBootAttributesForLayeredLayout(attributes, (LayeredLayout) this.layout);
-		}
-		else if (this.layout instanceof RepackagingLayout) {
-			addBootBootAttributesForRepackagingLayout(attributes, (RepackagingLayout) this.layout);
-		}
-		else {
-			addBootBootAttributesForPlainLayout(attributes, this.layout);
-		}
-	}
-
-	private void addBootBootAttributesForLayeredLayout(Attributes attributes, LayeredLayout layout) {
-		String layersIndexFileLocation = layout.getLayersIndexFileLocation();
-		putIfHasLength(attributes, BOOT_LAYERS_INDEX_ATTRIBUTE, layersIndexFileLocation);
-		putIfHasLength(attributes, BOOT_CLASSPATH_INDEX_ATTRIBUTE, layout.getClasspathIndexFileLocation());
-	}
-
-	private void addBootBootAttributesForRepackagingLayout(Attributes attributes, RepackagingLayout layout) {
-		attributes.putValue(BOOT_CLASSES_ATTRIBUTE, layout.getRepackagedClassesLocation());
-		putIfHasLength(attributes, BOOT_LIB_ATTRIBUTE, this.layout.getLibraryLocation("", LibraryScope.COMPILE));
-		putIfHasLength(attributes, BOOT_CLASSPATH_INDEX_ATTRIBUTE, layout.getClasspathIndexFileLocation());
-	}
-
-	private void addBootBootAttributesForPlainLayout(Attributes attributes, Layout layout) {
-		attributes.putValue(BOOT_CLASSES_ATTRIBUTE, this.layout.getClassesLocation());
-		putIfHasLength(attributes, BOOT_LIB_ATTRIBUTE, this.layout.getLibraryLocation("", LibraryScope.COMPILE));
-	}
-
-	private void putIfHasLength(Attributes attributes, String name, String value) {
-		if (StringUtils.hasLength(value)) {
-			attributes.putValue(name, value);
+			write(sourceJar, libraries, writer);
 		}
 	}
 
@@ -388,143 +126,4 @@ public class Repackager {
 		}
 	}
 
-	/**
-	 * Callback interface used to present a warning when finding the main class takes too
-	 * long.
-	 */
-	@FunctionalInterface
-	public interface MainClassTimeoutWarningListener {
-
-		/**
-		 * Handle a timeout warning.
-		 * @param duration the amount of time it took to find the main method
-		 * @param mainMethod the main method that was actually found
-		 */
-		void handleTimeoutWarning(long duration, String mainMethod);
-
-	}
-
-	/**
-	 * An {@code EntryTransformer} that renames entries by applying a prefix.
-	 */
-	private static final class RepackagingEntryTransformer implements EntryTransformer {
-
-		private final RepackagingLayout layout;
-
-		private final Layers layers;
-
-		private RepackagingEntryTransformer(RepackagingLayout layout, Layers layers) {
-			this.layout = layout;
-			this.layers = layers;
-		}
-
-		@Override
-		public JarArchiveEntry transform(JarArchiveEntry entry) {
-			if (entry.getName().equals("META-INF/INDEX.LIST")) {
-				return null;
-			}
-			if (!isTransformable(entry)) {
-				return entry;
-			}
-			String transformedName = transformName(entry.getName());
-			JarArchiveEntry transformedEntry = new JarArchiveEntry(transformedName);
-			transformedEntry.setTime(entry.getTime());
-			transformedEntry.setSize(entry.getSize());
-			transformedEntry.setMethod(entry.getMethod());
-			if (entry.getComment() != null) {
-				transformedEntry.setComment(entry.getComment());
-			}
-			transformedEntry.setCompressedSize(entry.getCompressedSize());
-			transformedEntry.setCrc(entry.getCrc());
-			if (entry.getCreationTime() != null) {
-				transformedEntry.setCreationTime(entry.getCreationTime());
-			}
-			if (entry.getExtra() != null) {
-				transformedEntry.setExtra(entry.getExtra());
-			}
-			if (entry.getLastAccessTime() != null) {
-				transformedEntry.setLastAccessTime(entry.getLastAccessTime());
-			}
-			if (entry.getLastModifiedTime() != null) {
-				transformedEntry.setLastModifiedTime(entry.getLastModifiedTime());
-			}
-			return transformedEntry;
-		}
-
-		private String transformName(String name) {
-			if (this.layout instanceof LayeredLayout) {
-				Layer layer = this.layers.getLayer(name);
-				Assert.state(layer != null, "Invalid 'null' layer from " + this.layers.getClass().getName());
-				return ((LayeredLayout) this.layout).getRepackagedClassesLocation(layer) + name;
-			}
-			return this.layout.getRepackagedClassesLocation() + name;
-		}
-
-		private boolean isTransformable(JarArchiveEntry entry) {
-			String name = entry.getName();
-			if (name.startsWith("META-INF/")) {
-				return name.equals("META-INF/aop.xml") || name.endsWith(".kotlin_module");
-			}
-			return !name.startsWith("BOOT-INF/") && !name.equals("module-info.class");
-		}
-
-	}
-
-	/**
-	 * An {@link UnpackHandler} that determines that an entry needs to be unpacked if a
-	 * library that requires unpacking has a matching entry name.
-	 */
-	private final class WritableLibraries implements UnpackHandler {
-
-		private final Map<String, Library> libraryEntryNames = new LinkedHashMap<>();
-
-		private WritableLibraries(Libraries libraries) throws IOException {
-			libraries.doWithLibraries((library) -> {
-				if (isZip(library.getFile())) {
-					String location = getLocation(library);
-					if (location != null) {
-						Library existing = this.libraryEntryNames.putIfAbsent(location + library.getName(), library);
-						Assert.state(existing == null, "Duplicate library " + library.getName());
-					}
-				}
-			});
-		}
-
-		private String getLocation(Library library) {
-			Layout layout = Repackager.this.layout;
-			if (layout instanceof LayeredLayout) {
-				Layers layers = Repackager.this.layers;
-				Layer layer = layers.getLayer(library);
-				Assert.state(layer != null, "Invalid 'null' library layer from " + layers.getClass().getName());
-				return ((LayeredLayout) layout).getLibraryLocation(library.getName(), library.getScope(), layer);
-			}
-			return layout.getLibraryLocation(library.getName(), library.getScope());
-		}
-
-		@Override
-		public boolean requiresUnpack(String name) {
-			Library library = this.libraryEntryNames.get(name);
-			return library != null && library.isUnpackRequired();
-		}
-
-		@Override
-		public String sha1Hash(String name) throws IOException {
-			Library library = this.libraryEntryNames.get(name);
-			Assert.notNull(library, "No library found for entry name '" + name + "'");
-			return FileUtils.sha1Hash(library.getFile());
-		}
-
-		private void write(JarWriter writer) throws IOException {
-			for (Entry<String, Library> entry : this.libraryEntryNames.entrySet()) {
-				writer.writeNestedLibrary(entry.getKey().substring(0, entry.getKey().lastIndexOf('/') + 1),
-						entry.getValue());
-			}
-			if (Repackager.this.layout instanceof RepackagingLayout) {
-				String location = ((RepackagingLayout) (Repackager.this.layout)).getClasspathIndexFileLocation();
-				writer.writeIndexFile(location, new ArrayList<>(this.libraryEntryNames.keySet()));
-			}
-		}
-
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/SizeCalculatingEntryWriter.java

@@ -0,0 +1,143 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+
+import org.springframework.util.StreamUtils;
+
+/**
+ * {@link EntryWriter} that always provides size information.
+ *
+ * @author Phillip Webb
+ */
+final class SizeCalculatingEntryWriter implements EntryWriter {
+
+	static final int THRESHOLD = 1024 * 20;
+
+	private final Object content;
+
+	private final int size;
+
+	private SizeCalculatingEntryWriter(EntryWriter entryWriter) throws IOException {
+		SizeCalculatingOutputStream outputStream = new SizeCalculatingOutputStream();
+		try {
+			entryWriter.write(outputStream);
+		}
+		finally {
+			outputStream.close();
+		}
+		this.content = outputStream.getContent();
+		this.size = outputStream.getSize();
+	}
+
+	@Override
+	public void write(OutputStream outputStream) throws IOException {
+		InputStream inputStream = getContentInputStream();
+		copy(inputStream, outputStream);
+	}
+
+	private InputStream getContentInputStream() throws FileNotFoundException {
+		if (this.content instanceof File) {
+			return new FileInputStream((File) this.content);
+		}
+		return new ByteArrayInputStream((byte[]) this.content);
+	}
+
+	private void copy(InputStream inputStream, OutputStream outputStream) throws IOException {
+		try {
+			StreamUtils.copy(inputStream, outputStream);
+		}
+		finally {
+			inputStream.close();
+		}
+	}
+
+	@Override
+	public int size() {
+		return this.size;
+	}
+
+	static EntryWriter get(EntryWriter entryWriter) throws IOException {
+		if (entryWriter == null || entryWriter.size() != -1) {
+			return entryWriter;
+		}
+		return new SizeCalculatingEntryWriter(entryWriter);
+	}
+
+	/**
+	 * {@link OutputStream} to calculate the size and allow content to be written again.
+	 */
+	private static class SizeCalculatingOutputStream extends OutputStream {
+
+		private int size = 0;
+
+		private File tempFile;
+
+		private OutputStream outputStream;
+
+		SizeCalculatingOutputStream() throws IOException {
+			this.tempFile = File.createTempFile("springboot-", "-entrycontent");
+			this.outputStream = new ByteArrayOutputStream();
+		}
+
+		@Override
+		public void write(int b) throws IOException {
+			write(new byte[] { (byte) b }, 0, 1);
+		}
+
+		@Override
+		public void write(byte[] b, int off, int len) throws IOException {
+			int updatedSize = this.size + len;
+			if (updatedSize > THRESHOLD && this.outputStream instanceof ByteArrayOutputStream) {
+				this.outputStream = convertToFileOutputStream((ByteArrayOutputStream) this.outputStream);
+			}
+			this.outputStream.write(b, off, len);
+			this.size = updatedSize;
+		}
+
+		private OutputStream convertToFileOutputStream(ByteArrayOutputStream byteArrayOutputStream) throws IOException {
+			FileOutputStream fileOutputStream = new FileOutputStream(this.tempFile);
+			StreamUtils.copy(byteArrayOutputStream.toByteArray(), fileOutputStream);
+			return fileOutputStream;
+		}
+
+		@Override
+		public void close() throws IOException {
+			this.outputStream.close();
+		}
+
+		Object getContent() {
+			return (this.outputStream instanceof ByteArrayOutputStream)
+					? ((ByteArrayOutputStream) this.outputStream).toByteArray() : this.tempFile;
+		}
+
+		int getSize() {
+			return this.size;
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/main/java/org/springframework/boot/loader/tools/ZipHeaderPeekInputStream.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.ByteArrayInputStream;
+import java.io.FilterInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.Arrays;
+
+/**
+ * {@link InputStream} that can peek ahead at zip header bytes.
+ *
+ * @author Phillip Webb
+ */
+class ZipHeaderPeekInputStream extends FilterInputStream {
+
+	private static final byte[] ZIP_HEADER = new byte[] { 0x50, 0x4b, 0x03, 0x04 };
+
+	private final byte[] header;
+
+	private final int headerLength;
+
+	private int position;
+
+	private ByteArrayInputStream headerStream;
+
+	protected ZipHeaderPeekInputStream(InputStream in) throws IOException {
+		super(in);
+		this.header = new byte[4];
+		this.headerLength = in.read(this.header);
+		this.headerStream = new ByteArrayInputStream(this.header, 0, this.headerLength);
+	}
+
+	@Override
+	public int read() throws IOException {
+		int read = (this.headerStream != null) ? this.headerStream.read() : -1;
+		if (read != -1) {
+			this.position++;
+			if (this.position >= this.headerLength) {
+				this.headerStream = null;
+			}
+			return read;
+		}
+		return super.read();
+	}
+
+	@Override
+	public int read(byte[] b) throws IOException {
+		return read(b, 0, b.length);
+	}
+
+	@Override
+	public int read(byte[] b, int off, int len) throws IOException {
+		int read = (this.headerStream != null) ? this.headerStream.read(b, off, len) : -1;
+		if (read <= 0) {
+			return readRemainder(b, off, len);
+		}
+		this.position += read;
+		if (read < len) {
+			int remainderRead = readRemainder(b, off + read, len - read);
+			if (remainderRead > 0) {
+				read += remainderRead;
+			}
+		}
+		if (this.position >= this.headerLength) {
+			this.headerStream = null;
+		}
+		return read;
+	}
+
+	boolean hasZipHeader() {
+		return Arrays.equals(this.header, ZIP_HEADER);
+	}
+
+	private int readRemainder(byte[] b, int off, int len) throws IOException {
+		int read = super.read(b, off, len);
+		if (read > 0) {
+			this.position += read;
+		}
+		return read;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/AbstractPackagerTests.java

@@ -0,0 +1,641 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Calendar;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.LinkedHashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+import java.util.jar.Attributes;
+import java.util.jar.Manifest;
+import java.util.stream.Collectors;
+import java.util.zip.Deflater;
+import java.util.zip.ZipEntry;
+import java.util.zip.ZipOutputStream;
+
+import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+import org.zeroturnaround.zip.ZipUtil;
+
+import org.springframework.boot.loader.tools.sample.ClassWithMainMethod;
+import org.springframework.boot.loader.tools.sample.ClassWithoutMainMethod;
+import org.springframework.util.FileCopyUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
+import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.ArgumentMatchers.eq;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Abstract class for {@link Packager} based tests.
+ *
+ * @param <P> The packager type
+ * @author Phillip Webb
+ * @author Andy Wilkinson
+ * @author Madhura Bhave
+ */
+abstract class AbstractPackagerTests<P extends Packager> {
+
+	protected static final Libraries NO_LIBRARIES = (callback) -> {
+	};
+
+	private static final long JAN_1_1980;
+	static {
+		Calendar calendar = Calendar.getInstance();
+		calendar.set(1980, 0, 1, 0, 0, 0);
+		calendar.set(Calendar.MILLISECOND, 0);
+		JAN_1_1980 = calendar.getTime().getTime();
+	}
+
+	private static final long JAN_1_1985;
+	static {
+		Calendar calendar = Calendar.getInstance();
+		calendar.set(1985, 0, 1, 0, 0, 0);
+		calendar.set(Calendar.MILLISECOND, 0);
+		JAN_1_1985 = calendar.getTime().getTime();
+	}
+
+	@TempDir
+	File tempDir;
+
+	protected TestJarFile testJarFile;
+
+	@BeforeEach
+	void setup() throws IOException {
+		this.testJarFile = new TestJarFile(this.tempDir);
+	}
+
+	@Test
+	void specificMainClass() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		P packager = createPackager();
+		packager.setMainClass("a.b.C");
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
+				.isEqualTo("org.springframework.boot.loader.JarLauncher");
+		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
+		assertThat(hasPackagedLauncherClasses()).isTrue();
+	}
+
+	@Test
+	void mainClassFromManifest() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		Manifest manifest = new Manifest();
+		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");
+		manifest.getMainAttributes().putValue("Main-Class", "a.b.C");
+		this.testJarFile.addManifest(manifest);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
+				.isEqualTo("org.springframework.boot.loader.JarLauncher");
+		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
+		assertThat(hasPackagedLauncherClasses()).isTrue();
+	}
+
+	@Test
+	void mainClassFound() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
+				.isEqualTo("org.springframework.boot.loader.JarLauncher");
+		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
+		assertThat(hasPackagedLauncherClasses()).isTrue();
+	}
+
+	@Test
+	void multipleMainClassFound() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		this.testJarFile.addClass("a/b/D.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		assertThatIllegalStateException().isThrownBy(() -> execute(packager, NO_LIBRARIES)).withMessageContaining(
+				"Unable to find a single main class from the following candidates [a.b.C, a.b.D]");
+	}
+
+	@Test
+	void noMainClass() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		P packager = createPackager(this.testJarFile.getFile());
+		assertThatIllegalStateException().isThrownBy(() -> execute(packager, NO_LIBRARIES))
+				.withMessageContaining("Unable to find main class");
+	}
+
+	@Test
+	void noMainClassAndLayoutIsNone() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		packager.setLayout(new Layouts.None());
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class")).isEqualTo("a.b.C");
+		assertThat(hasPackagedLauncherClasses()).isFalse();
+	}
+
+	@Test
+	void noMainClassAndLayoutIsNoneWithNoMain() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		P packager = createPackager();
+		packager.setLayout(new Layouts.None());
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes().getValue("Main-Class")).isNull();
+		assertThat(hasPackagedLauncherClasses()).isFalse();
+	}
+
+	@Test
+	void nullLibraries() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		assertThatIllegalArgumentException().isThrownBy(() -> execute(packager, null))
+				.withMessageContaining("Libraries must not be null");
+	}
+
+	@Test
+	void libraries() throws Exception {
+		TestJarFile libJar = new TestJarFile(this.tempDir);
+		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile = libJar.getFile();
+		File libJarFileToUnpack = libJar.getFile();
+		File libNonJarFile = new File(this.tempDir, "non-lib.jar");
+		FileCopyUtils.copy(new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8 }, libNonJarFile);
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		this.testJarFile.addFile("BOOT-INF/lib/" + libJarFileToUnpack.getName(), libJarFileToUnpack);
+		libJarFile.setLastModified(JAN_1_1980);
+		P packager = createPackager();
+		execute(packager, (callback) -> {
+			callback.library(new Library(libJarFile, LibraryScope.COMPILE));
+			callback.library(new Library(libJarFileToUnpack, LibraryScope.COMPILE, true));
+			callback.library(new Library(libNonJarFile, LibraryScope.COMPILE));
+		});
+		assertThat(hasPackagedEntry("BOOT-INF/lib/" + libJarFile.getName())).isTrue();
+		assertThat(hasPackagedEntry("BOOT-INF/lib/" + libJarFileToUnpack.getName())).isTrue();
+		assertThat(hasPackagedEntry("BOOT-INF/lib/" + libNonJarFile.getName())).isFalse();
+		ZipEntry entry = getPackagedEntry("BOOT-INF/lib/" + libJarFile.getName());
+		assertThat(entry.getTime()).isEqualTo(JAN_1_1985);
+		entry = getPackagedEntry("BOOT-INF/lib/" + libJarFileToUnpack.getName());
+		assertThat(entry.getComment()).startsWith("UNPACK:");
+		assertThat(entry.getComment()).hasSize(47);
+	}
+
+	@Test
+	void index() throws Exception {
+		TestJarFile libJar1 = new TestJarFile(this.tempDir);
+		libJar1.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile1 = libJar1.getFile();
+		TestJarFile libJar2 = new TestJarFile(this.tempDir);
+		libJar2.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile2 = libJar2.getFile();
+		TestJarFile libJar3 = new TestJarFile(this.tempDir);
+		libJar3.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile3 = libJar3.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		File file = this.testJarFile.getFile();
+		P packager = createPackager(file);
+		execute(packager, (callback) -> {
+			callback.library(new Library(libJarFile1, LibraryScope.COMPILE));
+			callback.library(new Library(libJarFile2, LibraryScope.COMPILE));
+			callback.library(new Library(libJarFile3, LibraryScope.COMPILE));
+		});
+		assertThat(hasPackagedEntry("BOOT-INF/classpath.idx")).isTrue();
+		String index = getPackagedEntryContent("BOOT-INF/classpath.idx");
+		String[] libraries = index.split("\\r?\\n");
+		assertThat(Arrays.asList(libraries)).contains("BOOT-INF/lib/" + libJarFile1.getName(),
+				"BOOT-INF/lib/" + libJarFile2.getName(), "BOOT-INF/lib/" + libJarFile3.getName());
+	}
+
+	@Test
+	void layeredLayout() throws Exception {
+		TestJarFile libJar1 = new TestJarFile(this.tempDir);
+		libJar1.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile1 = libJar1.getFile();
+		TestJarFile libJar2 = new TestJarFile(this.tempDir);
+		libJar2.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile2 = libJar2.getFile();
+		TestJarFile libJar3 = new TestJarFile(this.tempDir);
+		libJar3.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
+		File libJarFile3 = libJar3.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		TestLayers layers = new TestLayers();
+		layers.addLibrary(libJarFile1, "0001");
+		layers.addLibrary(libJarFile2, "0002");
+		layers.addLibrary(libJarFile3, "0003");
+		packager.setLayers(layers);
+		packager.setLayout(new Layouts.LayeredJar());
+		execute(packager, (callback) -> {
+			callback.library(new Library(libJarFile1, LibraryScope.COMPILE));
+			callback.library(new Library(libJarFile2, LibraryScope.COMPILE));
+			callback.library(new Library(libJarFile3, LibraryScope.COMPILE));
+		});
+		assertThat(hasPackagedEntry("BOOT-INF/classpath.idx")).isTrue();
+		String index = getPackagedEntryContent("BOOT-INF/classpath.idx");
+		String[] libraries = index.split("\\n");
+		List<String> expected = new ArrayList<>();
+		expected.add("BOOT-INF/layers/0001/lib/" + libJarFile1.getName());
+		expected.add("BOOT-INF/layers/0002/lib/" + libJarFile2.getName());
+		expected.add("BOOT-INF/layers/0003/lib/" + libJarFile3.getName());
+		assertThat(Arrays.asList(libraries)).containsExactly(expected.toArray(new String[0]));
+	}
+
+	@Test
+	void duplicateLibraries() throws Exception {
+		TestJarFile libJar = new TestJarFile(this.tempDir);
+		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File libJarFile = libJar.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		assertThatIllegalStateException().isThrownBy(() -> execute(packager, (callback) -> {
+			callback.library(new Library(libJarFile, LibraryScope.COMPILE, false));
+			callback.library(new Library(libJarFile, LibraryScope.COMPILE, false));
+		})).withMessageContaining("Duplicate library");
+	}
+
+	@Test
+	void customLayout() throws Exception {
+		TestJarFile libJar = new TestJarFile(this.tempDir);
+		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File libJarFile = libJar.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		Layout layout = mock(Layout.class);
+		LibraryScope scope = mock(LibraryScope.class);
+		given(layout.getLauncherClassName()).willReturn("testLauncher");
+		given(layout.getLibraryLocation(anyString(), eq(scope))).willReturn("test/");
+		given(layout.getLibraryLocation(anyString(), eq(LibraryScope.COMPILE))).willReturn("test-lib/");
+		packager.setLayout(layout);
+		execute(packager, (callback) -> callback.library(new Library(libJarFile, scope)));
+		assertThat(hasPackagedEntry("test/" + libJarFile.getName())).isTrue();
+		assertThat(getPackagedManifest().getMainAttributes().getValue("Spring-Boot-Lib")).isEqualTo("test-lib/");
+		assertThat(getPackagedManifest().getMainAttributes().getValue("Main-Class")).isEqualTo("testLauncher");
+	}
+
+	@Test
+	void customLayoutNoBootLib() throws Exception {
+		TestJarFile libJar = new TestJarFile(this.tempDir);
+		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File libJarFile = libJar.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		Layout layout = mock(Layout.class);
+		LibraryScope scope = mock(LibraryScope.class);
+		given(layout.getLauncherClassName()).willReturn("testLauncher");
+		packager.setLayout(layout);
+		execute(packager, (callback) -> callback.library(new Library(libJarFile, scope)));
+		assertThat(getPackagedManifest().getMainAttributes().getValue("Spring-Boot-Lib")).isNull();
+		assertThat(getPackagedManifest().getMainAttributes().getValue("Main-Class")).isEqualTo("testLauncher");
+	}
+
+	@Test
+	void springBootVersion() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes()).containsKey(new Attributes.Name("Spring-Boot-Version"));
+	}
+
+	@Test
+	void executableJarLayoutAttributes() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Lib"),
+				"BOOT-INF/lib/");
+		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Classes"),
+				"BOOT-INF/classes/");
+	}
+
+	@Test
+	void executableWarLayoutAttributes() throws Exception {
+		this.testJarFile.addClass("WEB-INF/classes/a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager(this.testJarFile.getFile("war"));
+		execute(packager, NO_LIBRARIES);
+		Manifest actualManifest = getPackagedManifest();
+		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Lib"),
+				"WEB-INF/lib/");
+		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Classes"),
+				"WEB-INF/classes/");
+	}
+
+	@Test
+	void nullCustomLayout() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		Packager packager = createPackager();
+		assertThatIllegalArgumentException().isThrownBy(() -> packager.setLayout(null))
+				.withMessageContaining("Layout must not be null");
+	}
+
+	@Test
+	void dontRecompressZips() throws Exception {
+		TestJarFile nested = new TestJarFile(this.tempDir);
+		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File nestedFile = nested.getFile();
+		this.testJarFile.addFile("test/nested.jar", nestedFile);
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, (callback) -> callback.library(new Library(nestedFile, LibraryScope.COMPILE)));
+		assertThat(getPackagedEntry("BOOT-INF/lib/" + nestedFile.getName()).getMethod()).isEqualTo(ZipEntry.STORED);
+		assertThat(getPackagedEntry("BOOT-INF/classes/test/nested.jar").getMethod()).isEqualTo(ZipEntry.STORED);
+	}
+
+	@Test
+	void unpackLibrariesTakePrecedenceOverExistingSourceEntries() throws Exception {
+		TestJarFile nested = new TestJarFile(this.tempDir);
+		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File nestedFile = nested.getFile();
+		String name = "BOOT-INF/lib/" + nestedFile.getName();
+		this.testJarFile.addFile(name, nested.getFile());
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, (callback) -> callback.library(new Library(nestedFile, LibraryScope.COMPILE, true)));
+		assertThat(getPackagedEntry(name).getComment()).startsWith("UNPACK:");
+	}
+
+	@Test
+	void existingSourceEntriesTakePrecedenceOverStandardLibraries() throws Exception {
+		TestJarFile nested = new TestJarFile(this.tempDir);
+		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File nestedFile = nested.getFile();
+		this.testJarFile.addFile("BOOT-INF/lib/" + nestedFile.getName(), nested.getFile());
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		long sourceLength = nestedFile.length();
+		execute(packager, (callback) -> {
+			nestedFile.delete();
+			File toZip = new File(this.tempDir, "to-zip");
+			toZip.createNewFile();
+			ZipUtil.packEntry(toZip, nestedFile);
+			callback.library(new Library(nestedFile, LibraryScope.COMPILE));
+		});
+		assertThat(getPackagedEntry("BOOT-INF/lib/" + nestedFile.getName()).getSize()).isEqualTo(sourceLength);
+	}
+
+	@Test
+	void metaInfIndexListIsRemovedFromRepackagedJar() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		File indexList = new File(this.tempDir, "INDEX.LIST");
+		indexList.createNewFile();
+		this.testJarFile.addFile("META-INF/INDEX.LIST", indexList);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("META-INF/INDEX.LIST")).isNull();
+	}
+
+	@Test
+	void customLayoutFactoryWithoutLayout() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		packager.setLayoutFactory(new TestLayoutFactory());
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("test")).isNotNull();
+	}
+
+	@Test
+	void customLayoutFactoryWithLayout() throws Exception {
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		packager.setLayoutFactory(new TestLayoutFactory());
+		packager.setLayout(new Layouts.Jar());
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("test")).isNull();
+	}
+
+	@Test
+	void metaInfAopXmlIsMovedBeneathBootInfClassesWhenRepackaged() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		File aopXml = new File(this.tempDir, "aop.xml");
+		aopXml.createNewFile();
+		this.testJarFile.addFile("META-INF/aop.xml", aopXml);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("META-INF/aop.xml")).isNull();
+		assertThat(getPackagedEntry("BOOT-INF/classes/META-INF/aop.xml")).isNotNull();
+	}
+
+	@Test
+	void allEntriesUseUnixPlatformAndUtf8NameEncoding() throws IOException {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		for (ZipArchiveEntry entry : getAllPackagedEntries()) {
+			assertThat(entry.getPlatform()).isEqualTo(ZipArchiveEntry.PLATFORM_UNIX);
+			assertThat(entry.getGeneralPurposeBit().usesUTF8ForNames()).isTrue();
+		}
+	}
+
+	@Test
+	void loaderIsWrittenFirstThenApplicationClassesThenLibraries() throws IOException {
+		this.testJarFile.addClass("com/example/Application.class", ClassWithMainMethod.class);
+		File libraryOne = createLibrary();
+		File libraryTwo = createLibrary();
+		File libraryThree = createLibrary();
+		P packager = createPackager();
+		execute(packager, (callback) -> {
+			callback.library(new Library(libraryOne, LibraryScope.COMPILE, false));
+			callback.library(new Library(libraryTwo, LibraryScope.COMPILE, true));
+			callback.library(new Library(libraryThree, LibraryScope.COMPILE, false));
+		});
+		assertThat(getPackagedEntryNames()).containsSubsequence("org/springframework/boot/loader/",
+				"BOOT-INF/classes/com/example/Application.class", "BOOT-INF/lib/" + libraryOne.getName(),
+				"BOOT-INF/lib/" + libraryTwo.getName(), "BOOT-INF/lib/" + libraryThree.getName());
+	}
+
+	@Test
+	void existingEntryThatMatchesUnpackLibraryIsMarkedForUnpack() throws IOException {
+		File library = createLibrary();
+		this.testJarFile.addClass("WEB-INF/classes/com/example/Application.class", ClassWithMainMethod.class);
+		this.testJarFile.addFile("WEB-INF/lib/" + library.getName(), library);
+		P packager = createPackager(this.testJarFile.getFile("war"));
+		packager.setLayout(new Layouts.War());
+		execute(packager, (callback) -> callback.library(new Library(library, LibraryScope.COMPILE, true)));
+		assertThat(getPackagedEntryNames()).containsSubsequence("org/springframework/boot/loader/",
+				"WEB-INF/classes/com/example/Application.class", "WEB-INF/lib/" + library.getName());
+		ZipEntry unpackLibrary = getPackagedEntry("WEB-INF/lib/" + library.getName());
+		assertThat(unpackLibrary.getComment()).startsWith("UNPACK:");
+	}
+
+	@Test
+	void layoutCanOmitLibraries() throws IOException {
+		TestJarFile libJar = new TestJarFile(this.tempDir);
+		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
+		File libJarFile = libJar.getFile();
+		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
+		P packager = createPackager();
+		Layout layout = mock(Layout.class);
+		LibraryScope scope = mock(LibraryScope.class);
+		packager.setLayout(layout);
+		execute(packager, (callback) -> callback.library(new Library(libJarFile, scope)));
+		assertThat(getPackagedEntryNames()).containsExactly("META-INF/", "META-INF/MANIFEST.MF", "a/", "a/b/",
+				"a/b/C.class");
+	}
+
+	@Test
+	void jarThatUsesCustomCompressionConfigurationCanBeRepackaged() throws IOException {
+		File source = new File(this.tempDir, "source.jar");
+		ZipOutputStream output = new ZipOutputStream(new FileOutputStream(source)) {
+			{
+				this.def = new Deflater(Deflater.NO_COMPRESSION, true);
+			}
+		};
+		byte[] data = new byte[1024 * 1024];
+		new Random().nextBytes(data);
+		ZipEntry entry = new ZipEntry("entry.dat");
+		output.putNextEntry(entry);
+		output.write(data);
+		output.closeEntry();
+		output.close();
+		P packager = createPackager(source);
+		packager.setMainClass("com.example.Main");
+		execute(packager, NO_LIBRARIES);
+	}
+
+	@Test
+	void moduleInfoClassRemainsInRootOfJarWhenRepackaged() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		this.testJarFile.addClass("module-info.class", ClassWithoutMainMethod.class);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("module-info.class")).isNotNull();
+		assertThat(getPackagedEntry("BOOT-INF/classes/module-info.class")).isNull();
+	}
+
+	@Test
+	void kotlinModuleMetadataMovesBeneathBootInfClassesWhenRepackaged() throws Exception {
+		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
+		File kotlinModule = new File(this.tempDir, "test.kotlin_module");
+		kotlinModule.createNewFile();
+		this.testJarFile.addFile("META-INF/test.kotlin_module", kotlinModule);
+		P packager = createPackager();
+		execute(packager, NO_LIBRARIES);
+		assertThat(getPackagedEntry("META-INF/test.kotlin_module")).isNull();
+		assertThat(getPackagedEntry("BOOT-INF/classes/META-INF/test.kotlin_module")).isNotNull();
+	}
+
+	private File createLibrary() throws IOException {
+		TestJarFile library = new TestJarFile(this.tempDir);
+		library.addClass("com/example/library/Library.class", ClassWithoutMainMethod.class);
+		return library.getFile();
+	}
+
+	protected final P createPackager() throws IOException {
+		return createPackager(this.testJarFile.getFile());
+	}
+
+	protected abstract P createPackager(File source);
+
+	protected abstract void execute(P packager, Libraries libraries) throws IOException;
+
+	protected Collection<String> getPackagedEntryNames() throws IOException {
+		return getAllPackagedEntries().stream().map(ZipArchiveEntry::getName).collect(Collectors.toList());
+	}
+
+	protected boolean hasPackagedLauncherClasses() throws IOException {
+		return hasPackagedEntry("org/springframework/boot/")
+				&& hasPackagedEntry("org/springframework/boot/loader/JarLauncher.class");
+	}
+
+	private boolean hasPackagedEntry(String name) throws IOException {
+		return getPackagedEntry(name) != null;
+	}
+
+	protected ZipEntry getPackagedEntry(String name) throws IOException {
+		return getAllPackagedEntries().stream().filter((entry) -> name.equals(entry.getName())).findFirst()
+				.orElse(null);
+
+	}
+
+	protected abstract Collection<ZipArchiveEntry> getAllPackagedEntries() throws IOException;
+
+	protected abstract Manifest getPackagedManifest() throws IOException;
+
+	protected abstract String getPackagedEntryContent(String name) throws IOException;
+
+	static class TestLayoutFactory implements LayoutFactory {
+
+		@Override
+		public Layout getLayout(File source) {
+			return new TestLayout();
+		}
+
+	}
+
+	static class TestLayout extends Layouts.Jar implements CustomLoaderLayout {
+
+		@Override
+		public void writeLoadedClasses(LoaderClassesWriter writer) throws IOException {
+			writer.writeEntry("test", new ByteArrayInputStream("test".getBytes()));
+		}
+
+	}
+
+	static class TestLayers implements Layers {
+
+		private static final Layer DEFAULT_LAYER = new Layer("default");
+
+		private Set<Layer> layers = new LinkedHashSet<Layer>();
+
+		private Map<String, Layer> libraries = new HashMap<>();
+
+		TestLayers() {
+			this.layers.add(DEFAULT_LAYER);
+		}
+
+		void addLibrary(File jarFile, String layerName) {
+			Layer layer = new Layer(layerName);
+			this.layers.add(layer);
+			this.libraries.put(jarFile.getName(), layer);
+		}
+
+		@Override
+		public Iterator<Layer> iterator() {
+			return this.layers.iterator();
+		}
+
+		@Override
+		public Layer getLayer(String name) {
+			return DEFAULT_LAYER;
+		}
+
+		@Override
+		public Layer getLayer(Library library) {
+			String name = new File(library.getName()).getName();
+			return this.libraries.getOrDefault(name, DEFAULT_LAYER);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/ImagePackagerTests.java

@@ -0,0 +1,92 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.jar.Manifest;
+import java.util.zip.ZipEntry;
+
+import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
+
+/**
+ * Tests for {@link ImagePackager}
+ *
+ * @author Phillip Webb
+ */
+class ImagePackagerTests extends AbstractPackagerTests<ImagePackager> {
+
+	private Map<ZipArchiveEntry, byte[]> entries;
+
+	@Override
+	protected ImagePackager createPackager(File source) {
+		return new ImagePackager(source);
+	}
+
+	@Override
+	protected void execute(ImagePackager packager, Libraries libraries) throws IOException {
+		this.entries = new LinkedHashMap<>();
+		packager.packageImage(libraries, this::save);
+	}
+
+	private void save(ZipEntry entry, EntryWriter writer) {
+		try {
+			this.entries.put((ZipArchiveEntry) entry, getContent(writer));
+		}
+		catch (IOException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+	private byte[] getContent(EntryWriter writer) throws IOException {
+		if (writer == null) {
+			return null;
+		}
+		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+		writer.write(outputStream);
+		return outputStream.toByteArray();
+	}
+
+	@Override
+	protected Collection<ZipArchiveEntry> getAllPackagedEntries() throws IOException {
+		return this.entries.keySet();
+	}
+
+	@Override
+	protected Manifest getPackagedManifest() throws IOException {
+		byte[] bytes = getEntryBytes("META-INF/MANIFEST.MF");
+		return (bytes != null) ? new Manifest(new ByteArrayInputStream(bytes)) : null;
+	}
+
+	@Override
+	protected String getPackagedEntryContent(String name) throws IOException {
+		byte[] bytes = getEntryBytes(name);
+		return (bytes != null) ? new String(bytes, StandardCharsets.UTF_8) : null;
+	}
+
+	private byte[] getEntryBytes(String name) throws IOException {
+		ZipEntry entry = getPackagedEntry(name);
+		return (entry != null) ? this.entries.get(entry) : null;
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/RepackagerTests.java

@@ -16,52 +16,29 @@
 
 package org.springframework.boot.loader.tools;
 
-import java.io.ByteArrayInputStream;
 import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
 import java.io.IOException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Calendar;
+import java.util.Collection;
 import java.util.Enumeration;
-import java.util.HashMap;
-import java.util.Iterator;
-import java.util.LinkedHashSet;
 import java.util.List;
-import java.util.Map;
-import java.util.Random;
-import java.util.Set;
-import java.util.jar.Attributes;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.jar.Manifest;
-import java.util.zip.Deflater;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipOutputStream;
 
 import org.apache.commons.compress.archivers.zip.ZipArchiveEntry;
 import org.apache.commons.compress.archivers.zip.ZipFile;
-import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.io.TempDir;
-import org.zeroturnaround.zip.ZipUtil;
 
 import org.springframework.boot.loader.tools.sample.ClassWithMainMethod;
-import org.springframework.boot.loader.tools.sample.ClassWithoutMainMethod;
 import org.springframework.util.FileCopyUtils;
-import org.springframework.util.StreamUtils;
+import org.springframework.util.StringUtils;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
-import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
-import static org.mockito.ArgumentMatchers.anyString;
-import static org.mockito.ArgumentMatchers.eq;
-import static org.mockito.BDDMockito.given;
-import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link Repackager}.
@@ -70,33 +47,9 @@ import static org.mockito.Mockito.mock;
  * @author Andy Wilkinson
  * @author Madhura Bhave
  */
-class RepackagerTests {
+class RepackagerTests extends AbstractPackagerTests<Repackager> {
 
-	private static final Libraries NO_LIBRARIES = (callback) -> {
-	};
-
-	private static final long JAN_1_1980;
-
-	private static final long JAN_1_1985;
-
-	static {
-		Calendar calendar = Calendar.getInstance();
-		calendar.set(1980, 0, 1, 0, 0, 0);
-		calendar.set(Calendar.MILLISECOND, 0);
-		JAN_1_1980 = calendar.getTime().getTime();
-		calendar.set(Calendar.YEAR, 1985);
-		JAN_1_1985 = calendar.getTime().getTime();
-	}
-
-	@TempDir
-	File tempDir;
-
-	private TestJarFile testJarFile;
-
-	@BeforeEach
-	void setup() throws IOException {
-		this.testJarFile = new TestJarFile(this.tempDir);
-	}
+	private File destination;
 
 	@Test
 	void nullSource() {
@@ -113,143 +66,55 @@ class RepackagerTests {
 		assertThatIllegalArgumentException().isThrownBy(() -> new Repackager(this.tempDir));
 	}
 
-	@Test
-	void specificMainClass() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.setMainClass("a.b.C");
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
-				.isEqualTo("org.springframework.boot.loader.JarLauncher");
-		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
-		assertThat(hasLauncherClasses(file)).isTrue();
-	}
-
-	@Test
-	void mainClassFromManifest() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		Manifest manifest = new Manifest();
-		manifest.getMainAttributes().putValue("Manifest-Version", "1.0");
-		manifest.getMainAttributes().putValue("Main-Class", "a.b.C");
-		this.testJarFile.addManifest(manifest);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
-				.isEqualTo("org.springframework.boot.loader.JarLauncher");
-		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
-		assertThat(hasLauncherClasses(file)).isTrue();
-	}
-
-	@Test
-	void mainClassFound() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
-				.isEqualTo("org.springframework.boot.loader.JarLauncher");
-		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
-		assertThat(hasLauncherClasses(file)).isTrue();
-	}
-
 	@Test
 	void jarIsOnlyRepackagedOnce() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
+		Repackager repackager = createRepackager(this.testJarFile.getFile(), false);
 		repackager.repackage(NO_LIBRARIES);
 		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
+		Manifest actualManifest = getPackagedManifest();
 		assertThat(actualManifest.getMainAttributes().getValue("Main-Class"))
 				.isEqualTo("org.springframework.boot.loader.JarLauncher");
 		assertThat(actualManifest.getMainAttributes().getValue("Start-Class")).isEqualTo("a.b.C");
-		assertThat(hasLauncherClasses(file)).isTrue();
+		assertThat(hasPackagedLauncherClasses()).isTrue();
 	}
 
 	@Test
-	void multipleMainClassFound() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		this.testJarFile.addClass("a/b/D.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		assertThatIllegalStateException().isThrownBy(() -> repackager.repackage(NO_LIBRARIES)).withMessageContaining(
-				"Unable to find a single main class from the following candidates [a.b.C, a.b.D]");
-	}
-
-	@Test
-	void noMainClass() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		assertThatIllegalStateException()
-				.isThrownBy(() -> new Repackager(this.testJarFile.getFile()).repackage(NO_LIBRARIES))
-				.withMessageContaining("Unable to find main class");
-	}
-
-	@Test
-	void noMainClassAndLayoutIsNone() throws Exception {
+	void sameSourceAndDestinationWithoutBackup() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
 		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.setLayout(new Layouts.None());
-		repackager.repackage(file, NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes().getValue("Main-Class")).isEqualTo("a.b.C");
-		assertThat(hasLauncherClasses(file)).isFalse();
-	}
-
-	@Test
-	void noMainClassAndLayoutIsNoneWithNoMain() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.setLayout(new Layouts.None());
-		repackager.repackage(file, NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes().getValue("Main-Class")).isNull();
-		assertThat(hasLauncherClasses(file)).isFalse();
+		Repackager repackager = createRepackager(file, false);
+		repackager.setBackupSource(false);
+		repackager.repackage(NO_LIBRARIES);
+		assertThat(new File(file.getParent(), file.getName() + ".original")).doesNotExist();
+		assertThat(hasPackagedLauncherClasses()).isTrue();
 	}
 
 	@Test
 	void sameSourceAndDestinationWithBackup() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
 		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
+		Repackager repackager = createRepackager(file, false);
 		repackager.repackage(NO_LIBRARIES);
 		assertThat(new File(file.getParent(), file.getName() + ".original")).exists();
-		assertThat(hasLauncherClasses(file)).isTrue();
-	}
-
-	@Test
-	void sameSourceAndDestinationWithoutBackup() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.setBackupSource(false);
-		repackager.repackage(NO_LIBRARIES);
-		assertThat(new File(file.getParent(), file.getName() + ".original")).doesNotExist();
-		assertThat(hasLauncherClasses(file)).isTrue();
+		assertThat(hasPackagedLauncherClasses()).isTrue();
 	}
 
 	@Test
 	void differentDestination() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
 		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "different.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
+		Repackager repackager = createRepackager(source, true);
+		execute(repackager, NO_LIBRARIES);
 		assertThat(new File(source.getParent(), source.getName() + ".original")).doesNotExist();
 		assertThat(hasLauncherClasses(source)).isFalse();
-		assertThat(hasLauncherClasses(dest)).isTrue();
+		assertThat(hasPackagedLauncherClasses()).isTrue();
 	}
 
 	@Test
 	void nullDestination() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		Repackager repackager = new Repackager(this.testJarFile.getFile());
+		Repackager repackager = createRepackager(this.testJarFile.getFile(), true);
 		assertThatIllegalArgumentException().isThrownBy(() -> repackager.repackage(null, NO_LIBRARIES))
 				.withMessageContaining("Invalid destination");
 	}
@@ -257,7 +122,7 @@ class RepackagerTests {
 	@Test
 	void destinationIsDirectory() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		Repackager repackager = new Repackager(this.testJarFile.getFile());
+		Repackager repackager = createRepackager(this.testJarFile.getFile(), true);
 		assertThatIllegalArgumentException().isThrownBy(() -> repackager.repackage(this.tempDir, NO_LIBRARIES))
 				.withMessageContaining("Invalid destination");
 	}
@@ -265,498 +130,92 @@ class RepackagerTests {
 	@Test
 	void overwriteDestination() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		Repackager repackager = new Repackager(this.testJarFile.getFile());
-		File dest = new File(this.tempDir, "dest.jar");
-		dest.createNewFile();
-		repackager.repackage(dest, NO_LIBRARIES);
-		assertThat(hasLauncherClasses(dest)).isTrue();
-	}
-
-	@Test
-	void nullLibraries() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		assertThatIllegalArgumentException().isThrownBy(() -> repackager.repackage(file, null))
-				.withMessageContaining("Libraries must not be null");
-	}
-
-	@Test
-	void libraries() throws Exception {
-		TestJarFile libJar = new TestJarFile(this.tempDir);
-		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile = libJar.getFile();
-		File libJarFileToUnpack = libJar.getFile();
-		File libNonJarFile = new File(this.tempDir, "non-lib.jar");
-		FileCopyUtils.copy(new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8 }, libNonJarFile);
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		this.testJarFile.addFile("BOOT-INF/lib/" + libJarFileToUnpack.getName(), libJarFileToUnpack);
-		File file = this.testJarFile.getFile();
-		libJarFile.setLastModified(JAN_1_1980);
-		Repackager repackager = new Repackager(file);
-		repackager.repackage((callback) -> {
-			callback.library(new Library(libJarFile, LibraryScope.COMPILE));
-			callback.library(new Library(libJarFileToUnpack, LibraryScope.COMPILE, true));
-			callback.library(new Library(libNonJarFile, LibraryScope.COMPILE));
-		});
-		assertThat(hasEntry(file, "BOOT-INF/lib/" + libJarFile.getName())).isTrue();
-		assertThat(hasEntry(file, "BOOT-INF/lib/" + libJarFileToUnpack.getName())).isTrue();
-		assertThat(hasEntry(file, "BOOT-INF/lib/" + libNonJarFile.getName())).isFalse();
-		JarEntry entry = getEntry(file, "BOOT-INF/lib/" + libJarFile.getName());
-		assertThat(entry.getTime()).isEqualTo(JAN_1_1985);
-		entry = getEntry(file, "BOOT-INF/lib/" + libJarFileToUnpack.getName());
-		assertThat(entry.getComment()).startsWith("UNPACK:");
-		assertThat(entry.getComment()).hasSize(47);
-	}
-
-	@Test
-	void index() throws Exception {
-		TestJarFile libJar1 = new TestJarFile(this.tempDir);
-		libJar1.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile1 = libJar1.getFile();
-		TestJarFile libJar2 = new TestJarFile(this.tempDir);
-		libJar2.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile2 = libJar2.getFile();
-		TestJarFile libJar3 = new TestJarFile(this.tempDir);
-		libJar3.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile3 = libJar3.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage((callback) -> {
-			callback.library(new Library(libJarFile1, LibraryScope.COMPILE));
-			callback.library(new Library(libJarFile2, LibraryScope.COMPILE));
-			callback.library(new Library(libJarFile3, LibraryScope.COMPILE));
-		});
-		assertThat(hasEntry(file, "BOOT-INF/classpath.idx")).isTrue();
-		ZipUtil.unpack(file, new File(file.getParent()));
-		try (FileInputStream inputStream = new FileInputStream(
-				new File(file.getParent() + "/BOOT-INF/classpath.idx"))) {
-			String index = StreamUtils.copyToString(inputStream, StandardCharsets.UTF_8);
-			String[] libraries = index.split("\\r?\\n");
-			assertThat(Arrays.asList(libraries)).contains("BOOT-INF/lib/" + libJarFile1.getName(),
-					"BOOT-INF/lib/" + libJarFile2.getName(), "BOOT-INF/lib/" + libJarFile3.getName());
-		}
-	}
-
-	@Test
-	void layeredLayout() throws Exception {
-		TestJarFile libJar1 = new TestJarFile(this.tempDir);
-		libJar1.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile1 = libJar1.getFile();
-		TestJarFile libJar2 = new TestJarFile(this.tempDir);
-		libJar2.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile2 = libJar2.getFile();
-		TestJarFile libJar3 = new TestJarFile(this.tempDir);
-		libJar3.addClass("a/b/C.class", ClassWithoutMainMethod.class, JAN_1_1985);
-		File libJarFile3 = libJar3.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		TestLayers layers = new TestLayers();
-		layers.addLibrary(libJarFile1, "0001");
-		layers.addLibrary(libJarFile2, "0002");
-		layers.addLibrary(libJarFile3, "0003");
-		repackager.setLayers(layers);
-		repackager.setLayout(new Layouts.LayeredJar());
-		repackager.repackage((callback) -> {
-			callback.library(new Library(libJarFile1, LibraryScope.COMPILE));
-			callback.library(new Library(libJarFile2, LibraryScope.COMPILE));
-			callback.library(new Library(libJarFile3, LibraryScope.COMPILE));
-		});
-		assertThat(hasEntry(file, "BOOT-INF/classpath.idx")).isTrue();
-		ZipUtil.unpack(file, new File(file.getParent()));
-		try (FileInputStream inputStream = new FileInputStream(
-				new File(file.getParent() + "/BOOT-INF/classpath.idx"))) {
-			String index = StreamUtils.copyToString(inputStream, StandardCharsets.UTF_8);
-			String[] libraries = index.split("\\r?\\n");
-			List<String> expected = new ArrayList<>();
-			expected.add("BOOT-INF/layers/0001/lib/" + libJarFile1.getName());
-			expected.add("BOOT-INF/layers/0002/lib/" + libJarFile2.getName());
-			expected.add("BOOT-INF/layers/0003/lib/" + libJarFile3.getName());
-			assertThat(Arrays.asList(libraries)).containsExactly(expected.toArray(new String[0]));
-		}
-	}
-
-	@Test
-	void duplicateLibraries() throws Exception {
-		TestJarFile libJar = new TestJarFile(this.tempDir);
-		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File libJarFile = libJar.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		assertThatIllegalStateException().isThrownBy(() -> repackager.repackage((callback) -> {
-			callback.library(new Library(libJarFile, LibraryScope.COMPILE, false));
-			callback.library(new Library(libJarFile, LibraryScope.COMPILE, false));
-		})).withMessageContaining("Duplicate library");
-	}
-
-	@Test
-	void customLayout() throws Exception {
-		TestJarFile libJar = new TestJarFile(this.tempDir);
-		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File libJarFile = libJar.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		Layout layout = mock(Layout.class);
-		LibraryScope scope = mock(LibraryScope.class);
-		given(layout.getLauncherClassName()).willReturn("testLauncher");
-		given(layout.getLibraryLocation(anyString(), eq(scope))).willReturn("test/");
-		given(layout.getLibraryLocation(anyString(), eq(LibraryScope.COMPILE))).willReturn("test-lib/");
-		repackager.setLayout(layout);
-		repackager.repackage((callback) -> callback.library(new Library(libJarFile, scope)));
-		assertThat(hasEntry(file, "test/" + libJarFile.getName())).isTrue();
-		assertThat(getManifest(file).getMainAttributes().getValue("Spring-Boot-Lib")).isEqualTo("test-lib/");
-		assertThat(getManifest(file).getMainAttributes().getValue("Main-Class")).isEqualTo("testLauncher");
-	}
-
-	@Test
-	void customLayoutNoBootLib() throws Exception {
-		TestJarFile libJar = new TestJarFile(this.tempDir);
-		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File libJarFile = libJar.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		Layout layout = mock(Layout.class);
-		LibraryScope scope = mock(LibraryScope.class);
-		given(layout.getLauncherClassName()).willReturn("testLauncher");
-		repackager.setLayout(layout);
-		repackager.repackage((callback) -> callback.library(new Library(libJarFile, scope)));
-		assertThat(getManifest(file).getMainAttributes().getValue("Spring-Boot-Lib")).isNull();
-		assertThat(getManifest(file).getMainAttributes().getValue("Main-Class")).isEqualTo("testLauncher");
-	}
-
-	@Test
-	void springBootVersion() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes()).containsKey(new Attributes.Name("Spring-Boot-Version"));
-	}
-
-	@Test
-	void executableJarLayoutAttributes() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Lib"),
-				"BOOT-INF/lib/");
-		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Classes"),
-				"BOOT-INF/classes/");
-	}
-
-	@Test
-	void executableWarLayoutAttributes() throws Exception {
-		this.testJarFile.addClass("WEB-INF/classes/a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile("war");
-		Repackager repackager = new Repackager(file);
-		repackager.repackage(NO_LIBRARIES);
-		Manifest actualManifest = getManifest(file);
-		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Lib"),
-				"WEB-INF/lib/");
-		assertThat(actualManifest.getMainAttributes()).containsEntry(new Attributes.Name("Spring-Boot-Classes"),
-				"WEB-INF/classes/");
-	}
-
-	@Test
-	void nullCustomLayout() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		Repackager repackager = new Repackager(this.testJarFile.getFile());
-		assertThatIllegalArgumentException().isThrownBy(() -> repackager.setLayout(null))
-				.withMessageContaining("Layout must not be null");
-	}
-
-	@Test
-	void dontRecompressZips() throws Exception {
-		TestJarFile nested = new TestJarFile(this.tempDir);
-		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File nestedFile = nested.getFile();
-		this.testJarFile.addFile("test/nested.jar", nestedFile);
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage((callback) -> callback.library(new Library(nestedFile, LibraryScope.COMPILE)));
-
-		try (JarFile jarFile = new JarFile(file)) {
-			assertThat(jarFile.getEntry("BOOT-INF/lib/" + nestedFile.getName()).getMethod()).isEqualTo(ZipEntry.STORED);
-			assertThat(jarFile.getEntry("BOOT-INF/classes/test/nested.jar").getMethod()).isEqualTo(ZipEntry.STORED);
-		}
+		Repackager repackager = createRepackager(this.testJarFile.getFile(), true);
+		this.destination.createNewFile();
+		repackager.repackage(this.destination, NO_LIBRARIES);
+		assertThat(hasLauncherClasses(this.destination)).isTrue();
 	}
 
 	@Test
 	void addLauncherScript() throws Exception {
 		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
 		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
+		Repackager repackager = createRepackager(source, true);
 		LaunchScript script = new MockLauncherScript("ABC");
-		repackager.repackage(dest, NO_LIBRARIES, script);
-		byte[] bytes = FileCopyUtils.copyToByteArray(dest);
+		repackager.repackage(this.destination, NO_LIBRARIES, script);
+		byte[] bytes = FileCopyUtils.copyToByteArray(this.destination);
 		assertThat(new String(bytes)).startsWith("ABC");
 		assertThat(hasLauncherClasses(source)).isFalse();
-		assertThat(hasLauncherClasses(dest)).isTrue();
+		assertThat(hasLauncherClasses(this.destination)).isTrue();
 		try {
-			assertThat(Files.getPosixFilePermissions(dest.toPath())).contains(PosixFilePermission.OWNER_EXECUTE);
+			assertThat(Files.getPosixFilePermissions(this.destination.toPath()))
+					.contains(PosixFilePermission.OWNER_EXECUTE);
 		}
 		catch (UnsupportedOperationException ex) {
 			// Probably running the test on Windows
 		}
 	}
 
-	@Test
-	void unpackLibrariesTakePrecedenceOverExistingSourceEntries() throws Exception {
-		TestJarFile nested = new TestJarFile(this.tempDir);
-		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File nestedFile = nested.getFile();
-		String name = "BOOT-INF/lib/" + nestedFile.getName();
-		this.testJarFile.addFile(name, nested.getFile());
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		repackager.repackage((callback) -> callback.library(new Library(nestedFile, LibraryScope.COMPILE, true)));
-		try (JarFile jarFile = new JarFile(file)) {
-			assertThat(jarFile.getEntry(name).getComment()).startsWith("UNPACK:");
-		}
+	private boolean hasLauncherClasses(File file) throws IOException {
+		return hasEntry(file, "org/springframework/boot/")
+				&& hasEntry(file, "org/springframework/boot/loader/JarLauncher.class");
 	}
 
-	@Test
-	void existingSourceEntriesTakePrecedenceOverStandardLibraries() throws Exception {
-		TestJarFile nested = new TestJarFile(this.tempDir);
-		nested.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File nestedFile = nested.getFile();
-		this.testJarFile.addFile("BOOT-INF/lib/" + nestedFile.getName(), nested.getFile());
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		long sourceLength = nestedFile.length();
-		repackager.repackage((callback) -> {
-			nestedFile.delete();
-			File toZip = new File(this.tempDir, "to-zip");
-			toZip.createNewFile();
-			ZipUtil.packEntry(toZip, nestedFile);
-			callback.library(new Library(nestedFile, LibraryScope.COMPILE));
-		});
-		try (JarFile jarFile = new JarFile(file)) {
-			assertThat(jarFile.getEntry("BOOT-INF/lib/" + nestedFile.getName()).getSize()).isEqualTo(sourceLength);
-		}
+	private boolean hasEntry(File file, String name) throws IOException {
+		return getEntry(file, name) != null;
 	}
 
-	@Test
-	void metaInfIndexListIsRemovedFromRepackagedJar() throws Exception {
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File indexList = new File(this.tempDir, "INDEX.LIST");
-		indexList.createNewFile();
-		this.testJarFile.addFile("META-INF/INDEX.LIST", indexList);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
-		try (JarFile jarFile = new JarFile(dest)) {
-			assertThat(jarFile.getEntry("META-INF/INDEX.LIST")).isNull();
+	private JarEntry getEntry(File file, String name) throws IOException {
+		try (JarFile jarFile = new JarFile(file)) {
+			return jarFile.getJarEntry(name);
 		}
 	}
 
-	@Test
-	void customLayoutFactoryWithoutLayout() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File source = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(source, new TestLayoutFactory());
-		repackager.repackage(NO_LIBRARIES);
-		JarFile jarFile = new JarFile(source);
-		assertThat(jarFile.getEntry("test")).isNotNull();
-		jarFile.close();
+	@Override
+	protected Repackager createPackager(File source) {
+		return createRepackager(source, true);
 	}
 
-	@Test
-	void customLayoutFactoryWithLayout() throws Exception {
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File source = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(source, new TestLayoutFactory());
-		repackager.setLayout(new Layouts.Jar());
-		repackager.repackage(NO_LIBRARIES);
-		JarFile jarFile = new JarFile(source);
-		assertThat(jarFile.getEntry("test")).isNull();
-		jarFile.close();
+	private Repackager createRepackager(File source, boolean differentDest) {
+		String ext = StringUtils.getFilenameExtension(source.getName());
+		this.destination = differentDest ? new File(this.tempDir, "dest." + ext) : source;
+		return new Repackager(source);
 	}
 
-	@Test
-	void metaInfAopXmlIsMovedBeneathBootInfClassesWhenRepackaged() throws Exception {
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File aopXml = new File(this.tempDir, "aop.xml");
-		aopXml.createNewFile();
-		this.testJarFile.addFile("META-INF/aop.xml", aopXml);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
-		try (JarFile jarFile = new JarFile(dest)) {
-			assertThat(jarFile.getEntry("META-INF/aop.xml")).isNull();
-			assertThat(jarFile.getEntry("BOOT-INF/classes/META-INF/aop.xml")).isNotNull();
-		}
+	@Override
+	protected void execute(Repackager packager, Libraries libraries) throws IOException {
+		packager.repackage(this.destination, libraries);
 	}
 
-	@Test
-	void allEntriesUseUnixPlatformAndUtf8NameEncoding() throws IOException {
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
-		try (ZipFile zip = new ZipFile(dest)) {
+	@Override
+	protected Collection<ZipArchiveEntry> getAllPackagedEntries() throws IOException {
+		List<ZipArchiveEntry> result = new ArrayList<>();
+		try (ZipFile zip = new ZipFile(this.destination)) {
 			Enumeration<ZipArchiveEntry> entries = zip.getEntries();
 			while (entries.hasMoreElements()) {
-				ZipArchiveEntry entry = entries.nextElement();
-				assertThat(entry.getPlatform()).isEqualTo(ZipArchiveEntry.PLATFORM_UNIX);
-				assertThat(entry.getGeneralPurposeBit().usesUTF8ForNames()).isTrue();
+				result.add(entries.nextElement());
 			}
 		}
+		return result;
 	}
 
-	@Test
-	void loaderIsWrittenFirstThenApplicationClassesThenLibraries() throws IOException {
-		this.testJarFile.addClass("com/example/Application.class", ClassWithMainMethod.class);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		File libraryOne = createLibrary();
-		File libraryTwo = createLibrary();
-		File libraryThree = createLibrary();
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, (callback) -> {
-			callback.library(new Library(libraryOne, LibraryScope.COMPILE, false));
-			callback.library(new Library(libraryTwo, LibraryScope.COMPILE, true));
-			callback.library(new Library(libraryThree, LibraryScope.COMPILE, false));
-		});
-		assertThat(getEntryNames(dest)).containsSubsequence("org/springframework/boot/loader/",
-				"BOOT-INF/classes/com/example/Application.class", "BOOT-INF/lib/" + libraryOne.getName(),
-				"BOOT-INF/lib/" + libraryTwo.getName(), "BOOT-INF/lib/" + libraryThree.getName());
-	}
-
-	@Test
-	void existingEntryThatMatchesUnpackLibraryIsMarkedForUnpack() throws IOException {
-		File library = createLibrary();
-		this.testJarFile.addClass("WEB-INF/classes/com/example/Application.class", ClassWithMainMethod.class);
-		this.testJarFile.addFile("WEB-INF/lib/" + library.getName(), library);
-		File source = this.testJarFile.getFile("war");
-		File dest = new File(this.tempDir, "dest.war");
-		Repackager repackager = new Repackager(source);
-		repackager.setLayout(new Layouts.War());
-		repackager.repackage(dest, (callback) -> callback.library(new Library(library, LibraryScope.COMPILE, true)));
-		assertThat(getEntryNames(dest)).containsSubsequence("org/springframework/boot/loader/",
-				"WEB-INF/classes/com/example/Application.class", "WEB-INF/lib/" + library.getName());
-		JarEntry unpackLibrary = getEntry(dest, "WEB-INF/lib/" + library.getName());
-		assertThat(unpackLibrary.getComment()).startsWith("UNPACK:");
-	}
-
-	@Test
-	void layoutCanOmitLibraries() throws IOException {
-		TestJarFile libJar = new TestJarFile(this.tempDir);
-		libJar.addClass("a/b/C.class", ClassWithoutMainMethod.class);
-		File libJarFile = libJar.getFile();
-		this.testJarFile.addClass("a/b/C.class", ClassWithMainMethod.class);
-		File file = this.testJarFile.getFile();
-		Repackager repackager = new Repackager(file);
-		Layout layout = mock(Layout.class);
-		LibraryScope scope = mock(LibraryScope.class);
-		repackager.setLayout(layout);
-		repackager.repackage((callback) -> callback.library(new Library(libJarFile, scope)));
-		assertThat(getEntryNames(file)).containsExactly("META-INF/", "META-INF/MANIFEST.MF", "a/", "a/b/",
-				"a/b/C.class");
-	}
-
-	@Test
-	void jarThatUsesCustomCompressionConfigurationCanBeRepackaged() throws IOException {
-		File source = new File(this.tempDir, "source.jar");
-		ZipOutputStream output = new ZipOutputStream(new FileOutputStream(source)) {
-			{
-				this.def = new Deflater(Deflater.NO_COMPRESSION, true);
-			}
-		};
-		byte[] data = new byte[1024 * 1024];
-		new Random().nextBytes(data);
-		ZipEntry entry = new ZipEntry("entry.dat");
-		output.putNextEntry(entry);
-		output.write(data);
-		output.closeEntry();
-		output.close();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.setMainClass("com.example.Main");
-		repackager.repackage(dest, NO_LIBRARIES);
-	}
-
-	@Test
-	void moduleInfoClassRemainsInRootOfJarWhenRepackaged() throws Exception {
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		this.testJarFile.addClass("module-info.class", ClassWithoutMainMethod.class);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
-		try (JarFile jarFile = new JarFile(dest)) {
-			assertThat(jarFile.getEntry("module-info.class")).isNotNull();
-			assertThat(jarFile.getEntry("BOOT-INF/classes/module-info.class")).isNull();
-		}
-	}
-
-	@Test
-	void kotlinModuleMetadataMovesBeneathBootInfClassesWhenRepackaged() throws Exception {
-		this.testJarFile.addClass("A.class", ClassWithMainMethod.class);
-		File kotlinModule = new File(this.tempDir, "test.kotlin_module");
-		kotlinModule.createNewFile();
-		this.testJarFile.addFile("META-INF/test.kotlin_module", kotlinModule);
-		File source = this.testJarFile.getFile();
-		File dest = new File(this.tempDir, "dest.jar");
-		Repackager repackager = new Repackager(source);
-		repackager.repackage(dest, NO_LIBRARIES);
-		try (JarFile jarFile = new JarFile(dest)) {
-			assertThat(jarFile.getEntry("META-INF/test.kotlin_module")).isNull();
-			assertThat(jarFile.getEntry("BOOT-INF/classes/META-INF/test.kotlin_module")).isNotNull();
-		}
-	}
-
-	private File createLibrary() throws IOException {
-		TestJarFile library = new TestJarFile(this.tempDir);
-		library.addClass("com/example/library/Library.class", ClassWithoutMainMethod.class);
-		return library.getFile();
-	}
-
-	private boolean hasLauncherClasses(File file) throws IOException {
-		return hasEntry(file, "org/springframework/boot/")
-				&& hasEntry(file, "org/springframework/boot/loader/JarLauncher.class");
-	}
-
-	private boolean hasEntry(File file, String name) throws IOException {
-		return getEntry(file, name) != null;
-	}
-
-	private JarEntry getEntry(File file, String name) throws IOException {
-		try (JarFile jarFile = new JarFile(file)) {
-			return jarFile.getJarEntry(name);
-		}
-	}
-
-	private Manifest getManifest(File file) throws IOException {
-		try (JarFile jarFile = new JarFile(file)) {
+	@Override
+	protected Manifest getPackagedManifest() throws IOException {
+		try (JarFile jarFile = new JarFile(this.destination)) {
 			return jarFile.getManifest();
 		}
 	}
 
-	private List<String> getEntryNames(File file) throws IOException {
-		List<String> entryNames = new ArrayList<>();
-		try (JarFile jarFile = new JarFile(file)) {
-			Enumeration<JarEntry> entries = jarFile.entries();
-			while (entries.hasMoreElements()) {
-				entryNames.add(entries.nextElement().getName());
+	@Override
+	protected String getPackagedEntryContent(String name) throws IOException {
+		try (ZipFile zip = new ZipFile(this.destination)) {
+			ZipArchiveEntry entry = zip.getEntry(name);
+			if (entry == null) {
+				return null;
 			}
+			byte[] bytes = FileCopyUtils.copyToByteArray(zip.getInputStream(entry));
+			return new String(bytes, StandardCharsets.UTF_8);
 		}
-		return entryNames;
 	}
 
 	static class MockLauncherScript implements LaunchScript {
@@ -774,58 +233,4 @@ class RepackagerTests {
 
 	}
 
-	static class TestLayoutFactory implements LayoutFactory {
-
-		@Override
-		public Layout getLayout(File source) {
-			return new TestLayout();
-		}
-
-	}
-
-	static class TestLayout extends Layouts.Jar implements CustomLoaderLayout {
-
-		@Override
-		public void writeLoadedClasses(LoaderClassesWriter writer) throws IOException {
-			writer.writeEntry("test", new ByteArrayInputStream("test".getBytes()));
-		}
-
-	}
-
-	static class TestLayers implements Layers {
-
-		private static final Layer DEFAULT_LAYER = new Layer("default");
-
-		private Set<Layer> layers = new LinkedHashSet<Layer>();
-
-		private Map<String, Layer> libraries = new HashMap<>();
-
-		TestLayers() {
-			this.layers.add(DEFAULT_LAYER);
-		}
-
-		void addLibrary(File jarFile, String layerName) {
-			Layer layer = new Layer(layerName);
-			this.layers.add(layer);
-			this.libraries.put(jarFile.getName(), layer);
-		}
-
-		@Override
-		public Iterator<Layer> iterator() {
-			return this.layers.iterator();
-		}
-
-		@Override
-		public Layer getLayer(String name) {
-			return DEFAULT_LAYER;
-		}
-
-		@Override
-		public Layer getLayer(Library library) {
-			String name = new File(library.getName()).getName();
-			return this.libraries.getOrDefault(name, DEFAULT_LAYER);
-		}
-
-	}
-
 }

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/SizeCalculatingEntryWriterTests.java

@@ -0,0 +1,81 @@
+/*
+ * Copyright 2012-2020 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.boot.loader.tools;
+
+import java.io.ByteArrayOutputStream;
+import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.util.Random;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SizeCalculatingEntryWriter}.
+ *
+ * @author Phillip Webb
+ */
+class SizeCalculatingEntryWriterTests {
+
+	@Test
+	void getWhenWithinThreshold() throws Exception {
+		TestEntryWriter original = new TestEntryWriter(SizeCalculatingEntryWriter.THRESHOLD - 1);
+		EntryWriter writer = SizeCalculatingEntryWriter.get(original);
+		assertThat(writer.size()).isEqualTo(original.getBytes().length);
+		assertThat(writeBytes(writer)).isEqualTo(original.getBytes());
+		assertThat(writer).extracting("content").isNotInstanceOf(File.class);
+	}
+
+	@Test
+	void getWhenExceedingThreshold() throws Exception {
+		TestEntryWriter original = new TestEntryWriter(SizeCalculatingEntryWriter.THRESHOLD + 1);
+		EntryWriter writer = SizeCalculatingEntryWriter.get(original);
+		assertThat(writer.size()).isEqualTo(original.getBytes().length);
+		assertThat(writeBytes(writer)).isEqualTo(original.getBytes());
+		assertThat(writer).extracting("content").isInstanceOf(File.class);
+	}
+
+	private byte[] writeBytes(EntryWriter writer) throws IOException {
+		ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
+		writer.write(outputStream);
+		outputStream.close();
+		return outputStream.toByteArray();
+	}
+
+	private static class TestEntryWriter implements EntryWriter {
+
+		private byte[] bytes;
+
+		TestEntryWriter(int size) {
+			this.bytes = new byte[size];
+			new Random().nextBytes(this.bytes);
+		}
+
+		byte[] getBytes() {
+			return this.bytes;
+		}
+
+		@Override
+		public void write(OutputStream outputStream) throws IOException {
+			outputStream.write(this.bytes);
+		}
+
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-loader-tools/src/test/java/org/springframework/boot/loader/tools/ZipHeaderPeekInputStreamTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,8 +21,6 @@ import java.io.IOException;
 
 import org.junit.jupiter.api.Test;
 
-import org.springframework.boot.loader.tools.JarWriter.ZipHeaderPeekInputStream;
-
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**