Allow a MethodReference to be produced from a GeneratedMethod

This commit updates GeneratedMethod and its underlying infrastructure
to be able to produce a MethodReference. This simplifies the need when
such a reference needs to be created manually and reuses more of what
MethodReference has to offer.

See spring-projectsgh-29005

spring-aop/src/main/java/org/springframework/aop/scope/ScopedProxyBeanRegistrationAotProcessor.java

@@ -163,8 +163,8 @@ public CodeBlock generateInstanceSupplierCode(GenerationContext generationContex
 						method.addStatement("return ($T) factory.getObject()",
 								beanClass);
 					});
-			return CodeBlock.of("$T.of($T::$L)", InstanceSupplier.class,
-					beanRegistrationCode.getClassName(), generatedMethod.getName());
+			return CodeBlock.of("$T.of($L)", InstanceSupplier.class,
+					generatedMethod.toMethodReference().toCodeBlock());
 		}
 
 	}

spring-beans/src/main/java/org/springframework/beans/factory/annotation/AutowiredAnnotationBeanPostProcessor.java

@@ -44,7 +44,6 @@
 import org.springframework.aot.generate.GeneratedClass;
 import org.springframework.aot.generate.GeneratedMethod;
 import org.springframework.aot.generate.GenerationContext;
-import org.springframework.aot.generate.MethodReference;
 import org.springframework.aot.hint.ExecutableMode;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.beans.BeanUtils;
@@ -944,8 +943,7 @@ public void applyTo(GenerationContext generationContext,
 				method.returns(this.target);
 				method.addCode(generateMethodCode(generationContext.getRuntimeHints()));
 			});
-			beanRegistrationCode.addInstancePostProcessor(
-					MethodReference.ofStatic(generatedClass.getName(), generateMethod.getName()));
+			beanRegistrationCode.addInstancePostProcessor(generateMethod.toMethodReference());
 
 			if (this.candidateResolver != null) {
 				registerHints(generationContext.getRuntimeHints());

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGenerator.java

@@ -107,16 +107,14 @@ MethodReference generateBeanDefinitionMethod(GenerationContext generationContext
 			GeneratedMethod generatedMethod = generateBeanDefinitionMethod(
 					generationContext, generatedClass.getName(), generatedMethods,
 					codeFragments, Modifier.PUBLIC);
-			return MethodReference.ofStatic(generatedClass.getName(),
-					generatedMethod.getName());
+			return generatedMethod.toMethodReference();
 		}
 		GeneratedMethods generatedMethods = beanRegistrationsCode.getMethods()
 				.withPrefix(getName());
 		GeneratedMethod generatedMethod = generateBeanDefinitionMethod(generationContext,
 				beanRegistrationsCode.getClassName(), generatedMethods, codeFragments,
 				Modifier.PRIVATE);
-		return MethodReference.ofStatic(beanRegistrationsCode.getClassName(),
-				generatedMethod.getName());
+		return generatedMethod.toMethodReference();
 	}
 
 	private BeanRegistrationCodeFragments getCodeFragments(GenerationContext generationContext,

spring-beans/src/main/java/org/springframework/beans/factory/aot/BeanRegistrationsAotContribution.java

@@ -65,8 +65,7 @@ public void applyTo(GenerationContext generationContext,
 		BeanRegistrationsCodeGenerator codeGenerator = new BeanRegistrationsCodeGenerator(generatedClass);
 		GeneratedMethod generatedMethod = codeGenerator.getMethods().add("registerBeanDefinitions", method ->
 				generateRegisterMethod(method, generationContext, codeGenerator));
-		beanFactoryInitializationCode.addInitializer(
-				MethodReference.of(generatedClass.getName(), generatedMethod.getName()));
+		beanFactoryInitializationCode.addInitializer(generatedMethod.toMethodReference());
 	}
 
 	private void generateRegisterMethod(MethodSpec.Builder method,

spring-beans/src/main/java/org/springframework/beans/factory/aot/InstanceSupplierCodeGenerator.java

@@ -296,8 +296,8 @@ private CodeBlock generateNewInstanceCodeForMethod(boolean dependsOnBean,
 				REGISTERED_BEAN_PARAMETER_NAME, declaringClass, factoryMethodName, args);
 	}
 
-	private CodeBlock generateReturnStatement(GeneratedMethod getInstanceMethod) {
-		return CodeBlock.of("$T.$L()", this.className, getInstanceMethod.getName());
+	private CodeBlock generateReturnStatement(GeneratedMethod generatedMethod) {
+		return generatedMethod.toMethodReference().toInvokeCodeBlock();
 	}
 
 	private CodeBlock generateWithGeneratorCode(boolean hasArguments, CodeBlock newInstance) {

spring-beans/src/test/java/org/springframework/beans/factory/aot/BeanDefinitionMethodGeneratorTests.java

@@ -129,8 +129,7 @@ void generateBeanDefinitionMethodWhenHasInstancePostProcessorGeneratesMethod() {
 							.addParameter(RegisteredBean.class, "registeredBean")
 							.addParameter(TestBean.class, "testBean")
 							.returns(TestBean.class).addCode("return new $T($S);", TestBean.class, "postprocessed"));
-			beanRegistrationCode.addInstancePostProcessor(MethodReference.ofStatic(
-					beanRegistrationCode.getClassName(), generatedMethod.getName()));
+			beanRegistrationCode.addInstancePostProcessor(generatedMethod.toMethodReference());
 		};
 		List<BeanRegistrationAotContribution> aotContributions = Collections
 				.singletonList(aotContribution);
@@ -167,8 +166,7 @@ void generateBeanDefinitionMethodWhenHasInstancePostProcessorAndFactoryMethodGen
 							.addParameter(RegisteredBean.class, "registeredBean")
 							.addParameter(TestBean.class, "testBean")
 							.returns(TestBean.class).addCode("return new $T($S);", TestBean.class, "postprocessed"));
-			beanRegistrationCode.addInstancePostProcessor(MethodReference.ofStatic(
-					beanRegistrationCode.getClassName(), generatedMethod.getName()));
+			beanRegistrationCode.addInstancePostProcessor(generatedMethod.toMethodReference());
 		};
 		List<BeanRegistrationAotContribution> aotContributions = Collections
 				.singletonList(aotContribution);

spring-context/src/main/java/org/springframework/context/annotation/ConfigurationClassPostProcessor.java

@@ -33,7 +33,6 @@
 import org.springframework.aop.framework.autoproxy.AutoProxyUtils;
 import org.springframework.aot.generate.GeneratedMethod;
 import org.springframework.aot.generate.GenerationContext;
-import org.springframework.aot.generate.MethodReference;
 import org.springframework.aot.hint.ResourceHints;
 import org.springframework.aot.hint.TypeReference;
 import org.springframework.beans.PropertyValues;
@@ -536,7 +535,7 @@ public void applyTo(GenerationContext generationContext,
 						.add("addImportAwareBeanPostProcessors", method ->
 								generateAddPostProcessorMethod(method, mappings));
 				beanFactoryInitializationCode
-						.addInitializer(MethodReference.of(generatedMethod.getName()));
+						.addInitializer(generatedMethod.toMethodReference());
 				ResourceHints hints = generationContext.getRuntimeHints().resources();
 				mappings.forEach(
 						(target, from) -> hints.registerType(TypeReference.of(from)));

spring-core/src/main/java/org/springframework/aot/generate/GeneratedClass.java

@@ -55,7 +55,7 @@ public final class GeneratedClass {
 	GeneratedClass(ClassName name, Consumer<TypeSpec.Builder> type) {
 		this.name = name;
 		this.type = type;
-		this.methods = new GeneratedMethods(this::generateSequencedMethodName);
+		this.methods = new GeneratedMethods(name, this::generateSequencedMethodName);
 	}
 
 

spring-core/src/main/java/org/springframework/aot/generate/GeneratedMethod.java

@@ -18,18 +18,24 @@
 
 import java.util.function.Consumer;
 
+import javax.lang.model.element.Modifier;
+
+import org.springframework.javapoet.ClassName;
 import org.springframework.javapoet.MethodSpec;
 import org.springframework.util.Assert;
 
 /**
  * A generated method.
  *
  * @author Phillip Webb
+ * @author Stephane Nicoll
  * @since 6.0
  * @see GeneratedMethods
  */
 public final class GeneratedMethod {
 
+	private final ClassName className;
+
 	private final String name;
 
 	private final MethodSpec methodSpec;
@@ -39,12 +45,14 @@ public final class GeneratedMethod {
 	 * Create a new {@link GeneratedMethod} instance with the given name. This
 	 * constructor is package-private since names should only be generated via
 	 * {@link GeneratedMethods}.
+	 * @param className the declaring class of the method
 	 * @param name the generated method name
 	 * @param method consumer to generate the method
 	 */
-	GeneratedMethod(String name, Consumer<MethodSpec.Builder> method) {
+	GeneratedMethod(ClassName className, String name, Consumer<MethodSpec.Builder> method) {
+		this.className = className;
 		this.name = name;
-		MethodSpec.Builder builder = MethodSpec.methodBuilder(getName());
+		MethodSpec.Builder builder = MethodSpec.methodBuilder(this.name);
 		method.accept(builder);
 		this.methodSpec = builder.build();
 		Assert.state(this.name.equals(this.methodSpec.name),
@@ -60,6 +68,16 @@ public String getName() {
 		return this.name;
 	}
 
+	/**
+	 * Return a {@link MethodReference} to this generated method.
+	 * @return a method reference
+	 */
+	public MethodReference toMethodReference() {
+		return (this.methodSpec.modifiers.contains(Modifier.STATIC)
+				? MethodReference.ofStatic(this.className, this.name)
+				: MethodReference.of(this.className, this.name));
+	}
+
 	/**
 	 * Return the {@link MethodSpec} for this generated method.
 	 * @return the method spec

spring-core/src/main/java/org/springframework/aot/generate/GeneratedMethods.java

@@ -22,6 +22,7 @@
 import java.util.function.Function;
 import java.util.stream.Stream;
 
+import org.springframework.javapoet.ClassName;
 import org.springframework.javapoet.MethodSpec;
 import org.springframework.javapoet.MethodSpec.Builder;
 import org.springframework.util.Assert;
@@ -30,11 +31,14 @@
  * A managed collection of generated methods.
  *
  * @author Phillip Webb
+ * @author Stephane Nicoll
  * @since 6.0
  * @see GeneratedMethod
  */
 public class GeneratedMethods {
 
+	private final ClassName className;
+
 	private final Function<MethodName, String> methodNameGenerator;
 
 	private final MethodName prefix;
@@ -44,18 +48,22 @@ public class GeneratedMethods {
 	/**
 	 * Create a new {@link GeneratedMethods} using the specified method name
 	 * generator.
+	 * @param className the declaring class name
 	 * @param methodNameGenerator the method name generator
 	 */
-	GeneratedMethods(Function<MethodName, String> methodNameGenerator) {
+	GeneratedMethods(ClassName className, Function<MethodName, String> methodNameGenerator) {
+		Assert.notNull(className, "'className' must not be null");
 		Assert.notNull(methodNameGenerator, "'methodNameGenerator' must not be null");
+		this.className = className;
 		this.methodNameGenerator = methodNameGenerator;
 		this.prefix = MethodName.NONE;
 		this.generatedMethods = new ArrayList<>();
 	}
 
-	private GeneratedMethods(Function<MethodName, String> methodNameGenerator,
+	private GeneratedMethods(ClassName className, Function<MethodName, String> methodNameGenerator,
 			MethodName prefix, List<GeneratedMethod> generatedMethods) {
 
+		this.className = className;
 		this.methodNameGenerator = methodNameGenerator;
 		this.prefix = prefix;
 		this.generatedMethods = generatedMethods;
@@ -82,15 +90,16 @@ public GeneratedMethod add(String[] suggestedNameParts, Consumer<Builder> method
 		Assert.notNull(suggestedNameParts, "'suggestedNameParts' must not be null");
 		Assert.notNull(method, "'method' must not be null");
 		String generatedName = this.methodNameGenerator.apply(this.prefix.and(suggestedNameParts));
-		GeneratedMethod generatedMethod = new GeneratedMethod(generatedName, method);
+		GeneratedMethod generatedMethod = new GeneratedMethod(this.className, generatedName, method);
 		this.generatedMethods.add(generatedMethod);
 		return generatedMethod;
 	}
 
 
 	public GeneratedMethods withPrefix(String prefix) {
 		Assert.notNull(prefix, "'prefix' must not be null");
-		return new GeneratedMethods(this.methodNameGenerator, this.prefix.and(prefix), this.generatedMethods);
+		return new GeneratedMethods(this.className, this.methodNameGenerator,
+				this.prefix.and(prefix), this.generatedMethods);
 	}
 
 	/**

spring-core/src/test/java/org/springframework/aot/generate/GeneratedMethodTests.java

@@ -18,8 +18,12 @@
 
 import java.util.function.Consumer;
 
+import javax.lang.model.element.Modifier;
+
 import org.junit.jupiter.api.Test;
 
+import org.springframework.javapoet.ClassName;
+import org.springframework.javapoet.CodeBlock;
 import org.springframework.javapoet.MethodSpec;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -29,30 +33,55 @@
  * Tests for {@link GeneratedMethod}.
  *
  * @author Phillip Webb
+ * @author Stephane Nicoll
  */
 class GeneratedMethodTests {
 
-	private static final Consumer<MethodSpec.Builder> methodSpecCustomizer = method -> {};
+	private static final ClassName TEST_CLASS_NAME = ClassName.get("com.example", "Test");
+
+	private static final Consumer<MethodSpec.Builder> emptyMethod = method -> {};
 
 	private static final String NAME = "spring";
 
 	@Test
 	void getNameReturnsName() {
-		GeneratedMethod generatedMethod = new GeneratedMethod(NAME, methodSpecCustomizer);
+		GeneratedMethod generatedMethod = new GeneratedMethod(TEST_CLASS_NAME, NAME, emptyMethod);
 		assertThat(generatedMethod.getName()).isSameAs(NAME);
 	}
 
 	@Test
 	void generateMethodSpecReturnsMethodSpec() {
-		GeneratedMethod generatedMethod = new GeneratedMethod(NAME, method -> method.addJavadoc("Test"));
+		GeneratedMethod generatedMethod = create(method -> method.addJavadoc("Test"));
 		assertThat(generatedMethod.getMethodSpec().javadoc).asString().contains("Test");
 	}
 
 	@Test
 	void generateMethodSpecWhenMethodNameIsChangedThrowsException() {
 		assertThatIllegalStateException().isThrownBy(() ->
-				new GeneratedMethod(NAME, method -> method.setName("badname")).getMethodSpec())
-			.withMessage("'method' consumer must not change the generated method name");
+						create(method -> method.setName("badname")).getMethodSpec())
+				.withMessage("'method' consumer must not change the generated method name");
+	}
+
+	@Test
+	void toMethodReferenceWithInstanceMethod() {
+		GeneratedMethod generatedMethod = create(emptyMethod);
+		MethodReference methodReference = generatedMethod.toMethodReference();
+		assertThat(methodReference).isNotNull();
+		assertThat(methodReference.toInvokeCodeBlock("test"))
+				.isEqualTo(CodeBlock.of("test.spring()"));
+	}
+
+	@Test
+	void toMethodReferenceWithStaticMethod() {
+		GeneratedMethod generatedMethod = create(method -> method.addModifiers(Modifier.STATIC));
+		MethodReference methodReference = generatedMethod.toMethodReference();
+		assertThat(methodReference).isNotNull();
+		assertThat(methodReference.toInvokeCodeBlock())
+				.isEqualTo(CodeBlock.of("com.example.Test.spring()"));
+	}
+
+	private GeneratedMethod create(Consumer<MethodSpec.Builder> method) {
+		return new GeneratedMethod(TEST_CLASS_NAME, NAME, method);
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/generate/GeneratedMethodsTests.java

@@ -23,6 +23,7 @@
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.javapoet.ClassName;
 import org.springframework.javapoet.MethodSpec;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -32,46 +33,57 @@
  * Tests for {@link GeneratedMethods}.
  *
  * @author Phillip Webb
+ * @author Stephane Nicoll
  */
 class GeneratedMethodsTests {
 
+	private static final ClassName TEST_CLASS_NAME = ClassName.get("com.example", "Test");
+
 	private static final Consumer<MethodSpec.Builder> methodSpecCustomizer = method -> {};
 
-	private final GeneratedMethods methods = new GeneratedMethods(MethodName::toString);
+	private final GeneratedMethods methods = new GeneratedMethods(TEST_CLASS_NAME, MethodName::toString);
+
+	@Test
+	void createWhenClassNameIsNullThrowsException() {
+		assertThatIllegalArgumentException().isThrownBy(() ->
+						new GeneratedMethods(null, MethodName::toString))
+				.withMessage("'className' must not be null");
+	}
 
 	@Test
 	void createWhenMethodNameGeneratorIsNullThrowsException() {
-		assertThatIllegalArgumentException().isThrownBy(() -> new GeneratedMethods(null))
+		assertThatIllegalArgumentException().isThrownBy(() ->
+						new GeneratedMethods(TEST_CLASS_NAME, null))
 				.withMessage("'methodNameGenerator' must not be null");
 	}
 
 	@Test
 	void createWithExistingGeneratorUsesGenerator() {
 		Function<MethodName, String> generator = name -> "__" + name.toString();
-		GeneratedMethods methods = new GeneratedMethods(generator);
+		GeneratedMethods methods = new GeneratedMethods(TEST_CLASS_NAME, generator);
 		assertThat(methods.add("test", methodSpecCustomizer).getName()).hasToString("__test");
 	}
 
 	@Test
 	void addWithStringNameWhenSuggestedMethodIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				this.methods.add((String) null, methodSpecCustomizer))
-		.withMessage("'suggestedName' must not be null");
+						this.methods.add((String) null, methodSpecCustomizer))
+				.withMessage("'suggestedName' must not be null");
 	}
 
 	@Test
 	void addWithStringNameWhenMethodIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				this.methods.add("test", null))
-		.withMessage("'method' must not be null");
+						this.methods.add("test", null))
+				.withMessage("'method' must not be null");
 	}
 
 	@Test
 	void addAddsMethod() {
 		this.methods.add("springBeans", methodSpecCustomizer);
 		this.methods.add("springContext", methodSpecCustomizer);
 		assertThat(this.methods.stream().map(GeneratedMethod::getName).map(Object::toString))
-						.containsExactly("springBeans", "springContext");
+				.containsExactly("springBeans", "springContext");
 	}
 
 	@Test

spring-orm/src/main/java/org/springframework/orm/jpa/persistenceunit/PersistenceManagedTypesBeanRegistrationAotProcessor.java

@@ -86,7 +86,7 @@ public CodeBlock generateInstanceSupplierCode(GenerationContext generationContex
 								List.class, toCodeBlock(persistenceManagedTypes.getManagedPackages()));
 						method.addStatement("return $T.of($L, $L)", beanType, "managedClassNames", "managedPackages");
 					});
-			return CodeBlock.of("() -> $T.$L()", beanRegistrationCode.getClassName(), generatedMethod.getName());
+			return generatedMethod.toMethodReference().toCodeBlock();
 		}
 
 		private CodeBlock toCodeBlock(List<String> values) {