Polish "Add runtime hints for Log4j Core 2"

See gh-46410

core/spring-boot/build.gradle

@@ -71,9 +71,6 @@ dependencies {
 	testImplementation("org.hibernate.validator:hibernate-validator")
 	testImplementation("org.jboss.logging:jboss-logging")
 	testImplementation("org.springframework.data:spring-data-r2dbc")
-
-	// Used in Log4J2RuntimeHintsTests
-	testRuntimeOnly("com.fasterxml.jackson.dataformat:jackson-dataformat-yaml")
 }
 
 def syncJavaTemplates = tasks.register("syncJavaTemplates", Sync) {

core/spring-boot/src/main/java/org/springframework/boot/logging/log4j2/Log4J2RuntimeHints.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2025-present the original author or authors.
+ * Copyright 2012-present 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.
@@ -26,42 +26,33 @@ import org.springframework.util.ClassUtils;
  * {@link RuntimeHintsRegistrar} implementation for {@link Log4J2LoggingSystem}.
  *
  * @author Piotr P. Karwasz
+ * @author Stephane Nicoll
  */
 class Log4J2RuntimeHints implements RuntimeHintsRegistrar {
 
 	@Override
 	public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
-		if (!ClassUtils.isPresent(Log4J2LoggingSystem.Factory.LOG4J_CORE_CONTEXT_FACTORY, classLoader)) {
-			return;
+		if (ClassUtils.isPresent(Log4J2LoggingSystem.Factory.LOG4J_CORE_CONTEXT_FACTORY, classLoader)) {
+			registerLog4j2Hints(hints, classLoader);
 		}
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.Factory.LOG4J_CORE_CONTEXT_FACTORY);
+	}
+
+	private void registerLog4j2Hints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.Factory.LOG4J_CORE_CONTEXT_FACTORY);
 		// Register default Log4j2 configuration files
 		hints.resources().registerPattern("org/springframework/boot/logging/log4j2/log4j2.xml");
 		hints.resources().registerPattern("org/springframework/boot/logging/log4j2/log4j2-file.xml");
 		hints.resources().registerPattern("log4j2.springboot");
 		// Declares the types that Log4j2LoggingSystem checks for existence reflectively.
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.JSON_TREE_PARSER_V2);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.JSON_TREE_PARSER_V3);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.PROPS_CONFIGURATION_FACTORY_V2);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.PROPS_CONFIGURATION_FACTORY_V3);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.YAML_TREE_PARSER_V2);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.YAML_CONFIGURATION_FACTORY_V2);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.YAML_CONFIGURATION_FACTORY_V3);
-		// Register JUL to Log4j 2 bridge handler
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.LOG4J_BRIDGE_HANDLER);
-		registerTypeForReachability(hints, classLoader, Log4J2LoggingSystem.LOG4J_LOG_MANAGER);
-		// Don't need to register the custom Log4j 2 plugins,
-		// since they will be registered by the Log4j 2 `GraalvmPluginProcessor`.
-	}
-
-	/**
-	 * Registers the type to prevent GraalVM from removing it during the native build.
-	 * @param hints the runtime hints to register with
-	 * @param classLoader the class loader to use for type resolution
-	 * @param typeName the name of the type to register
-	 */
-	private void registerTypeForReachability(RuntimeHints hints, @Nullable ClassLoader classLoader, String typeName) {
-		hints.reflection().registerTypeIfPresent(classLoader, typeName);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.JSON_TREE_PARSER_V2);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.JSON_TREE_PARSER_V3);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.PROPS_CONFIGURATION_FACTORY_V2);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.PROPS_CONFIGURATION_FACTORY_V3);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.YAML_TREE_PARSER_V2);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.YAML_CONFIGURATION_FACTORY_V2);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.YAML_CONFIGURATION_FACTORY_V3);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.LOG4J_BRIDGE_HANDLER);
+		hints.reflection().registerTypeIfPresent(classLoader, Log4J2LoggingSystem.LOG4J_LOG_MANAGER);
 	}
 
 }

core/spring-boot/src/test/java/org/springframework/boot/logging/log4j2/Log4J2RuntimeHintsTests.java

@@ -16,14 +16,21 @@
 
 package org.springframework.boot.logging.log4j2;
 
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.Arrays;
+
+import org.apache.logging.log4j.core.config.properties.PropertiesConfigurationFactory;
+import org.apache.logging.log4j.core.config.yaml.YamlConfigurationFactory;
 import org.apache.logging.log4j.core.impl.Log4jContextFactory;
 import org.apache.logging.log4j.jul.Log4jBridgeHandler;
 import org.apache.logging.log4j.jul.LogManager;
 import org.junit.jupiter.api.Test;
 
-import org.springframework.aot.hint.ReflectionHints;
 import org.springframework.aot.hint.RuntimeHints;
-import org.springframework.aot.hint.TypeReference;
+import org.springframework.aot.hint.predicate.ReflectionHintsPredicates;
+import org.springframework.aot.hint.predicate.ResourceHintsPredicates;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -31,43 +38,63 @@ import static org.assertj.core.api.Assertions.assertThat;
  * Tests for {@link Log4J2RuntimeHints}.
  *
  * @author Piotr P. Karwasz
+ * @author Stephane Nicoll
  */
 class Log4J2RuntimeHintsTests {
 
+	private static final ReflectionHintsPredicates reflectionHints = RuntimeHintsPredicates.reflection();
+
+	private static final ResourceHintsPredicates resourceHints = RuntimeHintsPredicates.resource();
+
 	@Test
 	void registersHintsForTypesCheckedByLog4J2LoggingSystem() {
-		ReflectionHints reflection = registerHints();
-		// Once Log4j Core is reachable, GraalVM will automatically
-		// add reachability metadata embedded in the Log4j Core jar and extensions.
-		assertThat(reflection.getTypeHint(Log4jContextFactory.class)).isNotNull();
-		assertThat(reflection.getTypeHint(Log4jBridgeHandler.class)).isNotNull();
-		assertThat(reflection.getTypeHint(LogManager.class)).isNotNull();
+		RuntimeHints runtimeHints = registerHints();
+		assertThat(reflectionHints.onType(Log4jContextFactory.class)).accepts(runtimeHints);
+		assertThat(reflectionHints.onType(Log4jBridgeHandler.class)).accepts(runtimeHints);
+		assertThat(reflectionHints.onType(LogManager.class)).accepts(runtimeHints);
+		assertThat(reflectionHints.onType(PropertiesConfigurationFactory.class)).accepts(runtimeHints);
+		assertThat(reflectionHints.onType(YamlConfigurationFactory.class)).accepts(runtimeHints);
 	}
 
-	/**
-	 *
-	 */
 	@Test
-	void registersHintsForConfigurationFileParsers() {
-		ReflectionHints reflection = registerHints();
-		// JSON
-		assertThat(reflection.getTypeHint(TypeReference.of("com.fasterxml.jackson.databind.ObjectMapper"))).isNotNull();
-		// YAML
-		assertThat(reflection.getTypeHint(TypeReference.of("com.fasterxml.jackson.dataformat.yaml.YAMLMapper")))
-			.isNotNull();
+	void registersHintsForLog4j2DefaultConfigurationFiles() {
+		RuntimeHints runtimeHints = registerHints();
+		assertThat(resourceHints.forResource("org/springframework/boot/logging/log4j2/log4j2.xml"))
+			.accepts(runtimeHints);
+		assertThat(resourceHints.forResource("org/springframework/boot/logging/log4j2/log4j2-file.xml"))
+			.accepts(runtimeHints);
 	}
 
 	@Test
 	void doesNotRegisterHintsWhenLog4jCoreIsNotAvailable() {
-		RuntimeHints hints = new RuntimeHints();
-		new Log4J2RuntimeHints().registerHints(hints, ClassLoader.getPlatformClassLoader());
-		assertThat(hints.reflection().typeHints()).isEmpty();
+		RuntimeHints runtimeHints = new RuntimeHints();
+		new Log4J2RuntimeHints().registerHints(runtimeHints, new HidePackagesClassLoader("org.apache.logging.log4j"));
+		assertThat(runtimeHints.reflection().typeHints()).isEmpty();
 	}
 
-	private ReflectionHints registerHints() {
+	private RuntimeHints registerHints() {
 		RuntimeHints hints = new RuntimeHints();
 		new Log4J2RuntimeHints().registerHints(hints, getClass().getClassLoader());
-		return hints.reflection();
+		return hints;
+	}
+
+	static final class HidePackagesClassLoader extends URLClassLoader {
+
+		private final String[] hiddenPackages;
+
+		HidePackagesClassLoader(String... hiddenPackages) {
+			super(new URL[0], HidePackagesClassLoader.class.getClassLoader());
+			this.hiddenPackages = hiddenPackages;
+		}
+
+		@Override
+		protected Class<?> loadClass(String name, boolean resolve) throws ClassNotFoundException {
+			if (Arrays.stream(this.hiddenPackages).anyMatch(name::startsWith)) {
+				throw new ClassNotFoundException();
+			}
+			return super.loadClass(name, resolve);
+		}
+
 	}
 
 }