Integrate class proxy generation in AOT processing

This commit updates ApplicationContextAotGenerator to register a
handler that process Cglib generated classes. The handler registers
such classes to the GeneratedFiles and provide a hint so that it
can be instantiated using reflection.

Closes gh-28954

spring-context/src/test/java/org/springframework/context/aot/ApplicationContextAotGeneratorTests.java

@@ -16,10 +16,15 @@
 
 package org.springframework.context.aot;
 
+import java.io.IOException;
 import java.util.function.BiConsumer;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.aot.generate.GeneratedFiles.Kind;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
 import org.springframework.aot.test.generator.compile.Compiled;
 import org.springframework.aot.test.generator.compile.TestCompiler;
 import org.springframework.beans.BeansException;
@@ -36,11 +41,13 @@ import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.RegisteredBean;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.ApplicationContextInitializer;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigUtils;
 import org.springframework.context.annotation.CommonAnnotationBeanPostProcessor;
 import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.context.testfixture.context.generator.SimpleComponent;
 import org.springframework.context.testfixture.context.generator.annotation.AutowiredComponent;
+import org.springframework.context.testfixture.context.generator.annotation.CglibConfiguration;
 import org.springframework.context.testfixture.context.generator.annotation.InitDestroyComponent;
 import org.springframework.core.testfixture.aot.generate.TestGenerationContext;
 
@@ -161,13 +168,30 @@ class ApplicationContextAotGeneratorTests {
 		});
 	}
 
-	@SuppressWarnings({ "rawtypes", "unchecked" })
-	private void testCompiledResult(GenericApplicationContext applicationContext,
-			BiConsumer<ApplicationContextInitializer<GenericApplicationContext>, Compiled> result) {
+	@Test
+	void processAheadOfTimeWhenHasCglibProxyWriteProxyAndGenerateReflectionHints() throws IOException {
+		GenericApplicationContext applicationContext = new AnnotationConfigApplicationContext();
+		applicationContext.registerBean(CglibConfiguration.class);
+		TestGenerationContext context = processAheadOfTime(applicationContext);
+		String proxyClassName = CglibConfiguration.class.getName() + "$$SpringCGLIB$$0";
+		assertThat(context.getGeneratedFiles()
+				.getGeneratedFileContent(Kind.CLASS, proxyClassName.replace('.', '/') + ".class")).isNotNull();
+		assertThat(RuntimeHintsPredicates.reflection().onType(TypeReference.of(proxyClassName))
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS)).accepts(context.getRuntimeHints());
+	}
+
+	private static TestGenerationContext processAheadOfTime(GenericApplicationContext applicationContext) {
 		ApplicationContextAotGenerator generator = new ApplicationContextAotGenerator();
 		TestGenerationContext generationContext = new TestGenerationContext();
 		generator.processAheadOfTime(applicationContext, generationContext);
 		generationContext.writeGeneratedContent();
+		return generationContext;
+	}
+
+	@SuppressWarnings({ "rawtypes", "unchecked" })
+	private void testCompiledResult(GenericApplicationContext applicationContext,
+			BiConsumer<ApplicationContextInitializer<GenericApplicationContext>, Compiled> result) {
+		TestGenerationContext generationContext = processAheadOfTime(applicationContext);
 		TestCompiler.forSystem().withFiles(generationContext.getGeneratedFiles()).compile(compiled ->
 				result.accept(compiled.getInstance(ApplicationContextInitializer.class), compiled));
 	}

spring-context/src/test/java/org/springframework/context/aot/GeneratedClassHandlerTests.java

@@ -0,0 +1,79 @@
+/*
+ * 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.context.aot;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.aot.generate.GeneratedFiles.Kind;
+import org.springframework.aot.generate.InMemoryGeneratedFiles;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.aot.hint.predicate.RuntimeHintsPredicates;
+import org.springframework.core.io.InputStreamSource;
+import org.springframework.core.testfixture.aot.generate.TestGenerationContext;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link GeneratedClassHandler}.
+ *
+ * @author Stephane Nicoll
+ */
+class GeneratedClassHandlerTests {
+
+	private static final byte[] TEST_CONTENT = new byte[] { 'a' };
+
+	private final TestGenerationContext generationContext;
+
+	private final GeneratedClassHandler handler;
+
+	public GeneratedClassHandlerTests() {
+		this.generationContext = new TestGenerationContext();
+		this.handler = new GeneratedClassHandler(this.generationContext);
+	}
+
+	@Test
+	void handlerGenerateRuntimeHints() {
+		String className = "com.example.Test$$Proxy$$1";
+		this.handler.accept(className, TEST_CONTENT);
+		assertThat(RuntimeHintsPredicates.reflection().onType(TypeReference.of(className))
+				.withMemberCategory(MemberCategory.INVOKE_DECLARED_CONSTRUCTORS))
+				.accepts(this.generationContext.getRuntimeHints());
+	}
+
+	@Test
+	void handlerRegisterGeneratedClass() throws IOException {
+		String className = "com.example.Test$$Proxy$$1";
+		this.handler.accept(className, TEST_CONTENT);
+		InMemoryGeneratedFiles generatedFiles = this.generationContext.getGeneratedFiles();
+		assertThat(generatedFiles.getGeneratedFiles(Kind.SOURCE)).isEmpty();
+		assertThat(generatedFiles.getGeneratedFiles(Kind.RESOURCE)).isEmpty();
+		String expectedPath = "com/example/Test$$Proxy$$1.class";
+		assertThat(generatedFiles.getGeneratedFiles(Kind.CLASS)).containsOnlyKeys(expectedPath);
+		assertContent(generatedFiles.getGeneratedFiles(Kind.CLASS).get(expectedPath), TEST_CONTENT);
+	}
+
+	private void assertContent(InputStreamSource source, byte[] expectedContent) throws IOException {
+		ByteArrayOutputStream out = new ByteArrayOutputStream();
+		source.getInputStream().transferTo(out);
+		assertThat(out.toByteArray()).isEqualTo(expectedContent);
+	}
+
+}