Fix Devtools PatternResolver Servlet support

Update ClassLoaderFilesResourcePatternResolver to support servlet
resources when it's being used with a WebApplicationContext.

Prior to commit 918e122ddc a `ResourceLoader` was not added to the
`ApplicationContext`, meaning that servlet resources could be found by
virtue of the protected `getResourceByPath()` method. Following commit
918e122ddc, the context `ResourceLoader` is set, meaning that all calls
to `getResource` delegate to the `ResourceLoader` and the
`ApplicationContext` methods are not invoked. Since the devtools
`ResourceLoader` wasn't Servlet aware, servlet resources could not
be found.

Fixes gh-7752

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/ClassLoaderFilesResourcePatternResolver.java

@@ -29,32 +29,54 @@ import org.springframework.boot.devtools.restart.classloader.ClassLoaderFile.Kin
 import org.springframework.boot.devtools.restart.classloader.ClassLoaderFileURLStreamHandler;
 import org.springframework.boot.devtools.restart.classloader.ClassLoaderFiles;
 import org.springframework.boot.devtools.restart.classloader.ClassLoaderFiles.SourceFolder;
+import org.springframework.context.ApplicationContext;
 import org.springframework.core.io.AbstractResource;
+import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
+import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.io.UrlResource;
 import org.springframework.core.io.support.PathMatchingResourcePatternResolver;
 import org.springframework.core.io.support.ResourcePatternResolver;
 import org.springframework.util.AntPathMatcher;
+import org.springframework.util.ClassUtils;
+import org.springframework.util.PathMatcher;
+import org.springframework.web.context.WebApplicationContext;
+import org.springframework.web.context.support.ServletContextResource;
+import org.springframework.web.context.support.ServletContextResourcePatternResolver;
 
 /**
  * A {@code ResourcePatternResolver} that considers {@link ClassLoaderFiles} when
  * resolving resources.
  *
  * @author Andy Wilkinson
+ * @author Phillip Webb
  */
 final class ClassLoaderFilesResourcePatternResolver implements ResourcePatternResolver {
 
 	private static final String[] LOCATION_PATTERN_PREFIXES = { CLASSPATH_ALL_URL_PREFIX,
 			CLASSPATH_URL_PREFIX };
 
-	private final ResourcePatternResolver delegate = new PathMatchingResourcePatternResolver();
+	private static final String WEB_CONTEXT_CLASS = "org.springframework.web.context."
+			+ "WebApplicationContext";
 
-	private final AntPathMatcher antPathMatcher = new AntPathMatcher();
+	private final ResourcePatternResolver delegate;
+
+	private final PathMatcher antPathMatcher = new AntPathMatcher();
 
 	private final ClassLoaderFiles classLoaderFiles;
 
-	ClassLoaderFilesResourcePatternResolver(ClassLoaderFiles classLoaderFiles) {
+	ClassLoaderFilesResourcePatternResolver(ApplicationContext applicationContext,
+			ClassLoaderFiles classLoaderFiles) {
 		this.classLoaderFiles = classLoaderFiles;
+		this.delegate = getResourcePatternResolverFactory()
+				.getResourcePatternResolver(applicationContext);
+	}
+
+	private ResourcePatternResolverFactory getResourcePatternResolverFactory() {
+		if (ClassUtils.isPresent(WEB_CONTEXT_CLASS, null)) {
+			return new WebResourcePatternResolverFactory();
+		}
+		return new ResourcePatternResolverFactory();
 	}
 
 	@Override
@@ -137,7 +159,7 @@ final class ClassLoaderFilesResourcePatternResolver implements ResourcePatternRe
 	 * A {@link Resource} that represents a {@link ClassLoaderFile} that has been
 	 * {@link Kind#DELETED deleted}.
 	 */
-	private final class DeletedClassLoaderFileResource extends AbstractResource {
+	static final class DeletedClassLoaderFileResource extends AbstractResource {
 
 		private final String name;
 
@@ -162,4 +184,60 @@ final class ClassLoaderFilesResourcePatternResolver implements ResourcePatternRe
 
 	}
 
+	/**
+	 * Factory used to create the {@link ResourcePatternResolver} delegate.
+	 */
+	private static class ResourcePatternResolverFactory {
+
+		public ResourcePatternResolver getResourcePatternResolver(
+				ApplicationContext applicationContext) {
+			return new PathMatchingResourcePatternResolver();
+		}
+
+	}
+
+	/**
+	 * {@link ResourcePatternResolverFactory} to be used when the classloader can access
+	 * {@link WebApplicationContext}.
+	 */
+	private static class WebResourcePatternResolverFactory
+			extends ResourcePatternResolverFactory {
+
+		@Override
+		public ResourcePatternResolver getResourcePatternResolver(
+				ApplicationContext applicationContext) {
+			if (applicationContext instanceof WebApplicationContext) {
+				return new ServletContextResourcePatternResolver(
+						new WebApplicationContextResourceLoader(
+								(WebApplicationContext) applicationContext));
+			}
+			return super.getResourcePatternResolver(applicationContext);
+		}
+
+	}
+
+	/**
+	 * {@link ResourceLoader} that optionally supports {@link ServletContextResource
+	 * ServletContextResources}.
+	 */
+	private static class WebApplicationContextResourceLoader
+			extends DefaultResourceLoader {
+
+		private final WebApplicationContext applicationContext;
+
+		WebApplicationContextResourceLoader(WebApplicationContext applicationContext) {
+			this.applicationContext = applicationContext;
+		}
+
+		@Override
+		protected Resource getResourceByPath(String path) {
+			if (this.applicationContext.getServletContext() != null) {
+				return new ServletContextResource(
+						this.applicationContext.getServletContext(), path);
+			}
+			return super.getResourceByPath(path);
+		}
+
+	}
+
 }

spring-boot-devtools/src/main/java/org/springframework/boot/devtools/restart/Restarter.java

@@ -51,6 +51,7 @@ import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.core.io.ResourceLoader;
 import org.springframework.util.Assert;
 import org.springframework.util.ReflectionUtils;
 
@@ -426,8 +427,9 @@ public class Restarter {
 	}
 
 	private void prepare(GenericApplicationContext applicationContext) {
-		applicationContext.setResourceLoader(
+		ResourceLoader resourceLoader = new ClassLoaderFilesResourcePatternResolver(
-				new ClassLoaderFilesResourcePatternResolver(this.classLoaderFiles));
+				applicationContext, this.classLoaderFiles);
+		applicationContext.setResourceLoader(resourceLoader);
 	}
 
 	private LeakSafeThread getLeakSafeThread() {

spring-boot-devtools/src/test/java/org/springframework/boot/devtools/restart/ClassLoaderFilesResourcePatternResolverTests.java

@@ -0,0 +1,120 @@
+/*
+ * Copyright 2012-2016 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
+ *
+ *      http://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.devtools.restart;
+
+import java.io.File;
+import java.io.IOException;
+
+import org.junit.Before;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import org.springframework.boot.devtools.restart.ClassLoaderFilesResourcePatternResolver.DeletedClassLoaderFileResource;
+import org.springframework.boot.devtools.restart.classloader.ClassLoaderFile;
+import org.springframework.boot.devtools.restart.classloader.ClassLoaderFile.Kind;
+import org.springframework.boot.devtools.restart.classloader.ClassLoaderFiles;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+import org.springframework.mock.web.MockServletContext;
+import org.springframework.util.FileCopyUtils;
+import org.springframework.web.context.support.GenericWebApplicationContext;
+import org.springframework.web.context.support.ServletContextResource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link ClassLoaderFilesResourcePatternResolver}.
+ *
+ * @author Phillip Webb
+ */
+public class ClassLoaderFilesResourcePatternResolverTests {
+
+	@Rule
+	public TemporaryFolder temp = new TemporaryFolder();
+
+	private ClassLoaderFiles files;
+
+	private ClassLoaderFilesResourcePatternResolver resolver;
+
+	@Before
+	public void setup() {
+		this.files = new ClassLoaderFiles();
+		this.resolver = new ClassLoaderFilesResourcePatternResolver(
+				new GenericApplicationContext(), this.files);
+	}
+
+	@Test
+	public void getClassLoaderShouldReturnClassLoader() throws Exception {
+		assertThat(this.resolver.getClassLoader()).isNotNull();
+	}
+
+	@Test
+	public void getResourceShouldReturnResource() throws Exception {
+		Resource resource = this.resolver.getResource("index.html");
+		assertThat(resource).isNotNull().isInstanceOf(ClassPathResource.class);
+	}
+
+	@Test
+	public void getResourceWhenHasServeletContextShouldReturnServletResource()
+			throws Exception {
+		GenericWebApplicationContext context = new GenericWebApplicationContext(
+				new MockServletContext());
+		this.resolver = new ClassLoaderFilesResourcePatternResolver(context, this.files);
+		Resource resource = this.resolver.getResource("index.html");
+		assertThat(resource).isNotNull().isInstanceOf(ServletContextResource.class);
+	}
+
+	@Test
+	public void getResourceWhenDeletedShouldReturnDeletedResource() throws Exception {
+		File folder = this.temp.newFolder();
+		File file = createFile(folder, "name.class");
+		this.files.addFile(folder.getName(), "name.class",
+				new ClassLoaderFile(Kind.DELETED, null));
+		Resource resource = this.resolver.getResource("file:" + file.getAbsolutePath());
+		assertThat(resource).isNotNull()
+				.isInstanceOf(DeletedClassLoaderFileResource.class);
+	}
+
+	@Test
+	public void getResourcesShouldReturnResources() throws Exception {
+		File folder = this.temp.newFolder();
+		createFile(folder, "name.class");
+		Resource[] resources = this.resolver
+				.getResources("file:" + folder.getAbsolutePath() + "/**");
+		assertThat(resources).isNotEmpty();
+	}
+
+	@Test
+	public void getResourcesWhenDeletedShouldFilterDeleted() throws Exception {
+		File folder = this.temp.newFolder();
+		createFile(folder, "name.class");
+		this.files.addFile(folder.getName(), "name.class",
+				new ClassLoaderFile(Kind.DELETED, null));
+		Resource[] resources = this.resolver
+				.getResources("file:" + folder.getAbsolutePath() + "/**");
+		assertThat(resources).isEmpty();
+	}
+
+	private File createFile(File folder, String name) throws IOException {
+		File file = new File(folder, name);
+		FileCopyUtils.copy("test".getBytes(), file);
+		return file;
+	}
+
+}

spring-boot-samples/spring-boot-sample-war/pom.xml

@@ -42,6 +42,13 @@
 				</exclusion>
 			</exclusions>
 		</dependency>
+		<!-- Provided -->
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-devtools</artifactId>
+			<scope>provided</scope>
+		</dependency>
+		<!-- Test -->
 		<dependency>
 			<groupId>org.springframework.boot</groupId>
 			<artifactId>spring-boot-starter-test</artifactId>