Add native hints for SpringFactoriesLoader file content

Add `SpringFactoriesLoaderRuntimeHintsRegistrar` which provides
native hints for `spring.factories` content.

Closes gh-27955

Co-authored-by: Phillip Webb <[email protected]>

spring-core/src/main/java/org/springframework/core/io/support/SpringFactoriesLoader.java

@@ -217,7 +217,9 @@ private List<String> loadFactoryNames(Class<?> factoryType) {
 	}
 
 	@Nullable
-	protected <T> T instantiateFactory(String implementationName, Class<T> type, @Nullable ArgumentResolver argumentResolver, FailureHandler failureHandler) {
+	protected <T> T instantiateFactory(String implementationName, Class<T> type,
+			@Nullable ArgumentResolver argumentResolver, FailureHandler failureHandler) {
+
 		try {
 			Class<?> factoryImplementationClass = ClassUtils.forName(implementationName, this.classLoader);
 			Assert.isTrue(type.isAssignableFrom(factoryImplementationClass),
@@ -333,7 +335,7 @@ public static SpringFactoriesLoader forResourceLocation(@Nullable ClassLoader cl
 		return loader;
 	}
 
-	private static Map<String, List<String>> loadFactoriesResource(ClassLoader classLoader, String resourceLocation) {
+	static Map<String, List<String>> loadFactoriesResource(ClassLoader classLoader, String resourceLocation) {
 		Map<String, List<String>> result = new LinkedHashMap<>();
 		try {
 			Enumeration<URL> urls = classLoader.getResources(resourceLocation);

spring-core/src/main/java/org/springframework/core/io/support/SpringFactoriesLoaderRuntimeHintsRegistrar.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2002-2022 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.core.io.support;
+
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.aot.hint.TypeHint;
+import org.springframework.core.log.LogMessage;
+import org.springframework.lang.Nullable;
+import org.springframework.util.ClassUtils;
+
+/**
+ * {@link RuntimeHintsRegistrar} to register hints for {@code spring.factories}.
+ *
+ * @author Brian Clozel
+ * @author Phillip Webb
+ * @since 6.0
+ * @see SpringFactoriesLoader
+ */
+class SpringFactoriesLoaderRuntimeHintsRegistrar implements RuntimeHintsRegistrar {
+
+	private static List<String> RESOURCE_LOCATIONS = List
+			.of(SpringFactoriesLoader.FACTORIES_RESOURCE_LOCATION);
+
+	private static final Consumer<TypeHint.Builder> HINT = builder -> builder
+			.withMembers(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS);
+
+	private final Log logger = LogFactory.getLog(SpringFactoriesLoaderRuntimeHintsRegistrar.class);
+
+
+	@Override
+	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		for (String resourceLocation : RESOURCE_LOCATIONS) {
+			registerHints(hints, classLoader, resourceLocation);
+		}
+	}
+
+	private void registerHints(RuntimeHints hints, ClassLoader classLoader,
+			String resourceLocation) {
+		hints.resources().registerPattern(resourceLocation);
+		Map<String, List<String>> factories = SpringFactoriesLoader
+				.loadFactoriesResource(classLoader, resourceLocation);
+		factories.forEach((factoryClassName, implementationClassNames) ->
+				registerHints(hints, classLoader, factoryClassName, implementationClassNames));
+	}
+
+	private void registerHints(RuntimeHints hints, ClassLoader classLoader,
+			String factoryClassName, List<String> implementationClassNames) {
+		Class<?> factoryClass = resolveClassName(classLoader, factoryClassName);
+		if(factoryClass == null) {
+			logger.trace(LogMessage.format("Skipping factories for [%s]", factoryClassName));
+			return;
+		}
+		logger.trace(LogMessage.format("Processing factories for [%s]", factoryClassName));
+		hints.reflection().registerType(factoryClass, HINT);
+		for (String implementationClassName : implementationClassNames) {
+			Class<?> implementationType = resolveClassName(classLoader, implementationClassName);
+			logger.trace(LogMessage.format("%s factory type [%s] and implementation [%s]",
+					(implementationType != null) ? "Processing" : "Skipping", factoryClassName, implementationClassName));
+			if (implementationType != null) {
+				hints.reflection().registerType(implementationType, HINT);
+			}
+		}
+	}
+
+	@Nullable
+	private Class<?> resolveClassName(ClassLoader classLoader, String factoryClassName) {
+		try {
+			return ClassUtils.resolveClassName(factoryClassName, classLoader);
+		}
+		catch (Exception ex) {
+			return null;
+		}
+	}
+
+}

spring-core/src/main/resources/META-INF/spring/aot.factories

@@ -1,2 +1,3 @@
 org.springframework.aot.hint.RuntimeHintsRegistrar=\
-org.springframework.core.annotation.CoreAnnotationsRuntimeHintsRegistrar
+org.springframework.core.annotation.CoreAnnotationsRuntimeHintsRegistrar,\
+org.springframework.core.io.support.SpringFactoriesLoaderRuntimeHintsRegistrar

spring-core/src/test/java/org/springframework/core/io/support/SpringFactoriesLoaderRuntimeHintsRegistrarTests.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2002-2022 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.core.io.support;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.RuntimeHints;
+import org.springframework.aot.hint.RuntimeHintsRegistrar;
+import org.springframework.aot.hint.TypeHint;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.util.ClassUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link SpringFactoriesLoaderRuntimeHintsRegistrar}.
+ *
+ * @author Phillip Webb
+ */
+class SpringFactoriesLoaderRuntimeHintsRegistrarTests {
+
+	private RuntimeHints hints;
+
+	@BeforeEach
+	void setup() {
+		this.hints = new RuntimeHints();
+		SpringFactoriesLoader.forResourceLocation("META-INF/spring/aot.factories")
+				.load(RuntimeHintsRegistrar.class).forEach(registrar -> registrar
+						.registerHints(this.hints, ClassUtils.getDefaultClassLoader()));
+	}
+
+	@Test
+	void resourceLocationHasHints() {
+		assertThat(this.hints.resources().resourcePatterns())
+				.anySatisfy(hint -> assertThat(hint.getIncludes())
+						.contains(SpringFactoriesLoader.FACTORIES_RESOURCE_LOCATION));
+	}
+
+	@Test
+	void factoryTypeHasHint() {
+		TypeReference type = TypeReference.of(DummyFactory.class);
+		assertThat(this.hints.reflection().getTypeHint(type))
+				.satisfies(this::expectedHints);
+	}
+
+	@Test
+	void factoryImplementationHasHint() {
+		TypeReference type = TypeReference.of(MyDummyFactory1.class);
+		assertThat(this.hints.reflection().getTypeHint(type))
+				.satisfies(this::expectedHints);
+	}
+
+	private void expectedHints(TypeHint hint) {
+		assertThat(hint.getMemberCategories())
+				.containsExactly(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS);
+	}
+
+}