Use ClassLoader with ArchitectureCheck

Prior to this commit, certain rules, like BeanPostProcessor,
did not work with external classes. This commit ensures that
ArchRules are executed within a context ClassLoader that includes
all classes from the compile classpath.

See gh-45202

Signed-off-by: Dmytro Nosan <[email protected]>

Author: nosan

Diff for: buildSrc/src/main/java/org/springframework/boot/build/architecture/ArchitectureCheck.java

@@ -18,11 +18,15 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.StandardOpenOption;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
+import java.util.concurrent.Callable;
 import java.util.function.Supplier;
 import java.util.stream.Stream;
 
@@ -33,11 +37,13 @@
 import org.gradle.api.DefaultTask;
 import org.gradle.api.Task;
 import org.gradle.api.Transformer;
+import org.gradle.api.file.ConfigurableFileCollection;
 import org.gradle.api.file.DirectoryProperty;
 import org.gradle.api.file.FileCollection;
 import org.gradle.api.file.FileTree;
 import org.gradle.api.provider.ListProperty;
 import org.gradle.api.provider.Property;
+import org.gradle.api.tasks.Classpath;
 import org.gradle.api.tasks.IgnoreEmptyDirectories;
 import org.gradle.api.tasks.Input;
 import org.gradle.api.tasks.InputFiles;
@@ -58,6 +64,7 @@
  * @author Scott Frederick
  * @author Ivan Malutin
  * @author Phillip Webb
+ * @author Dmytro Nosan
  */
 public abstract class ArchitectureCheck extends DefaultTask {
 
@@ -80,14 +87,17 @@ private List<String> asDescriptions(List<ArchRule> rules) {
 	}
 
 	@TaskAction
-	void checkArchitecture() throws IOException {
-		JavaClasses javaClasses = new ClassFileImporter().importPaths(classFilesPaths());
-		List<EvaluationResult> violations = evaluate(javaClasses).filter(EvaluationResult::hasViolation).toList();
-		File outputFile = getOutputDirectory().file("failure-report.txt").get().getAsFile();
-		writeViolationReport(violations, outputFile);
-		if (!violations.isEmpty()) {
-			throw new VerificationException("Architecture check failed. See '" + outputFile + "' for details.");
-		}
+	void checkArchitecture() throws Exception {
+		withCompileClasspath(() -> {
+			JavaClasses javaClasses = new ClassFileImporter().importPaths(classFilesPaths());
+			List<EvaluationResult> violations = evaluate(javaClasses).filter(EvaluationResult::hasViolation).toList();
+			File outputFile = getOutputDirectory().file("failure-report.txt").get().getAsFile();
+			writeViolationReport(violations, outputFile);
+			if (!violations.isEmpty()) {
+				throw new VerificationException("Architecture check failed. See '" + outputFile + "' for details.");
+			}
+			return null;
+		});
 	}
 
 	private List<Path> classFilesPaths() {
@@ -98,8 +108,24 @@ private Stream<EvaluationResult> evaluate(JavaClasses javaClasses) {
 		return getRules().get().stream().map((rule) -> rule.evaluate(javaClasses));
 	}
 
+	private void withCompileClasspath(Callable<?> callable) throws Exception {
+		ClassLoader previous = Thread.currentThread().getContextClassLoader();
+		try {
+			List<URL> urls = new ArrayList<>();
+			for (File file : getCompileClasspath().getFiles()) {
+				urls.add(file.toURI().toURL());
+			}
+			ClassLoader classLoader = new URLClassLoader(urls.toArray(new URL[0]), getClass().getClassLoader());
+			Thread.currentThread().setContextClassLoader(classLoader);
+			callable.call();
+		}
+		finally {
+			Thread.currentThread().setContextClassLoader(previous);
+		}
+	}
+
 	private void writeViolationReport(List<EvaluationResult> violations, File outputFile) throws IOException {
-		outputFile.getParentFile().mkdirs();
+		Files.createDirectories(outputFile.getParentFile().toPath());
 		StringBuilder report = new StringBuilder();
 		for (EvaluationResult violation : violations) {
 			report.append(violation.getFailureReport());
@@ -126,6 +152,10 @@ final FileTree getInputClasses() {
 		return this.classes.getAsFileTree();
 	}
 
+	@InputFiles
+	@Classpath
+	public abstract ConfigurableFileCollection getCompileClasspath();
+
 	@Optional
 	@InputFiles
 	@PathSensitive(PathSensitivity.RELATIVE)

Diff for: buildSrc/src/main/java/org/springframework/boot/build/architecture/ArchitecturePlugin.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2024 the original author or authors.
+ * Copyright 2012-2025 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.
@@ -49,6 +49,7 @@ private void registerTasks(Project project) {
 			TaskProvider<ArchitectureCheck> checkPackageTangles = project.getTasks()
 				.register("checkArchitecture" + StringUtils.capitalize(sourceSet.getName()), ArchitectureCheck.class,
 						(task) -> {
+							task.getCompileClasspath().from(sourceSet.getCompileClasspath());
 							task.setClasses(sourceSet.getOutput().getClassesDirs());
 							task.getResourcesDirectory().set(sourceSet.getOutput().getResourcesDir());
 							task.dependsOn(sourceSet.getProcessResourcesTaskName());