Remove hardcoded versions from MavenBuild

Use the dependencies BOM to ensure versions used in the `MavenBuild`
test class are always aligned.

Closes gh-23936

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/build.gradle

@@ -9,6 +9,7 @@ plugins {
 description = "Spring Boot Maven Plugin"
 
 configurations {
+	dependenciesBom
 	documentation
 }
 
@@ -16,6 +17,8 @@ dependencies {
 	compileOnly("org.apache.maven.plugin-tools:maven-plugin-annotations")
 	compileOnly("org.sonatype.plexus:plexus-build-api")
 
+	dependenciesBom(project(path: ":spring-boot-project:spring-boot-dependencies", configuration: "effectiveBom"))
+
 	implementation(project(":spring-boot-project:spring-boot-tools:spring-boot-buildpack-platform"))
 	implementation(project(":spring-boot-project:spring-boot-tools:spring-boot-loader-tools"))
 	implementation("org.apache.maven.shared:maven-common-artifact-filters")
@@ -41,12 +44,23 @@ dependencies {
 	testRuntimeOnly("org.junit.platform:junit-platform-launcher")
 }
 
+task syncSpringBootDependenciesBom(type: Sync) {
+	destinationDir = file("${buildDir}/generated/sources/dependencies-bom/org/springframework/boot/maven")
+	from configurations.dependenciesBom
+}
+
 syncDocumentationSourceForAsciidoctor {
 	from(documentPluginGoals) {
 		into "asciidoc/goals"
 	}
 }
 
+sourceSets {
+	main {
+		output.dir("${buildDir}/generated/sources/dependencies-bom", builtBy: "syncSpringBootDependenciesBom")
+	}
+}
+
 tasks.withType(org.asciidoctor.gradle.jvm.AbstractAsciidoctorTask) {
 	doFirst {
 		def versionEl = version.split("\\.")

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/MavenBuild.java

@@ -17,11 +17,9 @@
 package org.springframework.boot.maven;
 
 import java.io.File;
-import java.io.FileReader;
 import java.io.FileWriter;
 import java.io.IOException;
 import java.io.PrintWriter;
-import java.io.Reader;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
@@ -62,7 +60,7 @@ class MavenBuild {
 
 	private final File temp;
 
-	private final Map<String, String> pomReplacements = new HashMap<>();
+	private final Map<String, String> pomReplacements;
 
 	private final List<String> goals = new ArrayList<>();
 
@@ -74,24 +72,38 @@ class MavenBuild {
 
 	MavenBuild(File home) {
 		this.home = home;
+		this.temp = createTempDirectory();
+		this.pomReplacements = getPomReplacements();
+	}
+
+	private File createTempDirectory() {
 		try {
-			this.temp = Files.createTempDirectory("maven-build").toFile().getCanonicalFile();
+			return Files.createTempDirectory("maven-build").toFile().getCanonicalFile();
 		}
 		catch (IOException ex) {
-			throw new RuntimeException(ex);
+			throw new IllegalStateException(ex);
 		}
-		this.pomReplacements.put("java.version", "1.8");
+	}
-		this.pomReplacements.put("project.groupId", "org.springframework.boot");
+
-		this.pomReplacements.put("project.artifactId", "spring-boot-maven-plugin");
+	private Map<String, String> getPomReplacements() {
-		this.pomReplacements.put("project.version", determineVersion());
+		Map<String, String> replacements = new HashMap<>();
-		this.pomReplacements.put("log4j2.version", "2.13.3");
+		SpringBootDependenciesBom bom = new SpringBootDependenciesBom();
-		this.pomReplacements.put("maven-jar-plugin.version", "3.2.0");
+		replacements.put("java.version", "1.8");
-		this.pomReplacements.put("maven-toolchains-plugin.version", "3.0.0");
+		replacements.put("project.groupId", "org.springframework.boot");
-		this.pomReplacements.put("maven-war-plugin.version", "3.2.3");
+		replacements.put("project.artifactId", "spring-boot-maven-plugin");
-		this.pomReplacements.put("build-helper-maven-plugin.version", "3.0.0");
+		replacements.put("project.version", bom.get("version"));
-		this.pomReplacements.put("spring-framework.version", "5.2.10.RELEASE");
+		putReplacement(replacements, bom, "log4j2.version");
-		this.pomReplacements.put("jakarta-servlet.version", "4.0.4");
+		putReplacement(replacements, bom, "maven-jar-plugin.version");
-		this.pomReplacements.put("kotlin.version", "1.3.72");
+		putReplacement(replacements, bom, "maven-war-plugin.version");
+		putReplacement(replacements, bom, "build-helper-maven-plugin.version");
+		putReplacement(replacements, bom, "spring-framework.version");
+		putReplacement(replacements, bom, "jakarta-servlet.version");
+		putReplacement(replacements, bom, "kotlin.version");
+		return Collections.unmodifiableMap(replacements);
+	}
+
+	private void putReplacement(Map<String, String> replacements, SpringBootDependenciesBom bom, String property) {
+		replacements.put(property, bom.get("properties/" + property));
 	}
 
 	MavenBuild project(String project) {
@@ -196,21 +208,6 @@ class MavenBuild {
 		}
 	}
 
-	private String determineVersion() {
-		File gradleProperties = new File("gradle.properties").getAbsoluteFile();
-		while (!gradleProperties.isFile()) {
-			gradleProperties = new File(gradleProperties.getParentFile().getParentFile(), "gradle.properties");
-		}
-		Properties properties = new Properties();
-		try (Reader reader = new FileReader(gradleProperties)) {
-			properties.load(reader);
-			return properties.getProperty("version");
-		}
-		catch (IOException ex) {
-			throw new RuntimeException(ex);
-		}
-	}
-
 	/**
 	 * Action to take on a maven project directory.
 	 */

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/java/org/springframework/boot/maven/SpringBootDependenciesBom.java

@@ -0,0 +1,80 @@
+/*
+ * Copyright 2012-2021 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.maven;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import javax.xml.parsers.DocumentBuilder;
+import javax.xml.parsers.DocumentBuilderFactory;
+import javax.xml.parsers.ParserConfigurationException;
+import javax.xml.xpath.XPath;
+import javax.xml.xpath.XPathConstants;
+import javax.xml.xpath.XPathExpressionException;
+import javax.xml.xpath.XPathFactory;
+
+import org.w3c.dom.Document;
+import org.w3c.dom.Node;
+import org.xml.sax.SAXException;
+
+import org.springframework.util.Assert;
+
+/**
+ * Provides access to values in the spring-boot-dependencies effective BOM.
+ *
+ * @author Phillip Webb
+ */
+class SpringBootDependenciesBom {
+
+	private static final String XML = "spring-boot-dependencies-effective-bom.xml";
+
+	private final Document document;
+
+	private final XPath xpath;
+
+	SpringBootDependenciesBom() {
+		this.document = loadDocument();
+		this.xpath = XPathFactory.newInstance().newXPath();
+	}
+
+	private Document loadDocument() {
+		try {
+			try (InputStream inputStream = getClass().getResourceAsStream(XML)) {
+				DocumentBuilderFactory builderFactory = DocumentBuilderFactory.newInstance();
+				DocumentBuilder builder = builderFactory.newDocumentBuilder();
+				return builder.parse(inputStream);
+			}
+		}
+		catch (ParserConfigurationException | SAXException | IOException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+	String get(String expression) {
+		try {
+			Node node = (Node) this.xpath.compile("/project/" + expression).evaluate(this.document,
+					XPathConstants.NODE);
+			String text = (node != null) ? node.getTextContent() : null;
+			Assert.hasLength(text, () -> "No result for expression " + expression);
+			return text;
+		}
+		catch (XPathExpressionException ex) {
+			throw new IllegalStateException(ex);
+		}
+	}
+
+}

spring-boot-project/spring-boot-tools/spring-boot-maven-plugin/src/intTest/projects/run-toolchains/pom.xml

@@ -15,7 +15,7 @@
 			<plugin>
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-toolchains-plugin</artifactId>
-				<version>@maven-toolchains-plugin.version@</version>
+				<version>3.0.0</version>
 				<executions>
 					<execution>
 						<goals>