@value can be used as aliased meta-annotation

Issue: SPR-13603

Author: jhoeller

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2014 the original author or authors.
+ * Copyright 2002-2015 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.
@@ -32,6 +32,8 @@
 import org.springframework.beans.factory.support.GenericTypeAwareAutowireCandidateResolver;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.core.MethodParameter;
+import org.springframework.core.annotation.AnnotatedElementUtils;
+import org.springframework.core.annotation.AnnotationAttributes;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
@@ -315,25 +317,20 @@ public Object getSuggestedValue(DependencyDescriptor descriptor) {
 	 * Determine a suggested value from any of the given candidate annotations.
 	 */
 	protected Object findValue(Annotation[] annotationsToSearch) {
-		for (Annotation annotation : annotationsToSearch) {
-			if (this.valueAnnotationType.isInstance(annotation)) {
-				return extractValue(annotation);
-			}
-		}
-		for (Annotation annotation : annotationsToSearch) {
-			Annotation metaAnn = annotation.annotationType().getAnnotation(this.valueAnnotationType);
-			if (metaAnn != null) {
-				return extractValue(metaAnn);
-			}
+		AnnotationAttributes attr = AnnotatedElementUtils.getMergedAnnotationAttributes(
+				AnnotatedElementUtils.forAnnotations(annotationsToSearch), this.valueAnnotationType);
+		if (attr != null) {
+			return extractValue(attr);
 		}
 		return null;
 	}
 
 	/**
 	 * Extract the value attribute from the given annotation.
+	 * @since 4.3
 	 */
-	protected Object extractValue(Annotation valueAnnotation) {
-		Object value = AnnotationUtils.getValue(valueAnnotation);
+	protected Object extractValue(AnnotationAttributes attr) {
+		Object value = attr.get(AnnotationUtils.VALUE);
 		if (value == null) {
 			throw new IllegalStateException("Value annotation must have a value attribute");
 		}

spring-context/src/test/java/org/springframework/context/annotation/configuration/AutowiredConfigurationTests.java

@@ -17,6 +17,8 @@
 package org.springframework.context.annotation.configuration;
 
 import java.io.IOException;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.List;
 import java.util.Optional;
 import javax.inject.Provider;
@@ -35,6 +37,7 @@
 import org.springframework.context.annotation.Scope;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.core.annotation.AliasFor;
 import org.springframework.core.io.ClassPathResource;
 import org.springframework.core.io.Resource;
 import org.springframework.tests.sample.beans.Colour;
@@ -119,6 +122,20 @@ public void testValueInjection() {
 		doTestValueInjection(context);
 	}
 
+	@Test
+	public void testValueInjectionWithMetaAnnotation() {
+		AnnotationConfigApplicationContext context =
+				new AnnotationConfigApplicationContext(ValueConfigWithMetaAnnotation.class);
+		doTestValueInjection(context);
+	}
+
+	@Test
+	public void testValueInjectionWithAliasedMetaAnnotation() {
+		AnnotationConfigApplicationContext context =
+				new AnnotationConfigApplicationContext(ValueConfigWithAliasedMetaAnnotation.class);
+		doTestValueInjection(context);
+	}
+
 	@Test
 	public void testValueInjectionWithProviderFields() {
 		AnnotationConfigApplicationContext context =
@@ -291,6 +308,73 @@ public TestBean testBean2() {
 	}
 
 
+	@Value("#{systemProperties[myProp]}")
+	@Retention(RetentionPolicy.RUNTIME)
+	public @interface MyProp {
+	}
+
+
+	@Configuration
+	@Scope("prototype")
+	static class ValueConfigWithMetaAnnotation {
+
+		@MyProp
+		private String name;
+
+		private String name2;
+
+		@MyProp
+		public void setName2(String name) {
+			this.name2 = name;
+		}
+
+		@Bean @Scope("prototype")
+		public TestBean testBean() {
+			return new TestBean(name);
+		}
+
+		@Bean @Scope("prototype")
+		public TestBean testBean2() {
+			return new TestBean(name2);
+		}
+	}
+
+
+	@Value("")
+	@Retention(RetentionPolicy.RUNTIME)
+	public @interface AliasedProp {
+
+		@AliasFor(annotation = Value.class)
+		String value();
+	}
+
+
+	@Configuration
+	@Scope("prototype")
+	static class ValueConfigWithAliasedMetaAnnotation {
+
+		@AliasedProp("#{systemProperties[myProp]}")
+		private String name;
+
+		private String name2;
+
+		@AliasedProp("#{systemProperties[myProp]}")
+		public void setName2(String name) {
+			this.name2 = name;
+		}
+
+		@Bean @Scope("prototype")
+		public TestBean testBean() {
+			return new TestBean(name);
+		}
+
+		@Bean @Scope("prototype")
+		public TestBean testBean2() {
+			return new TestBean(name2);
+		}
+	}
+
+
 	@Configuration
 	static class ValueConfigWithProviderFields {
 

spring-core/src/main/java/org/springframework/core/annotation/AnnotatedElementUtils.java

@@ -97,6 +97,35 @@ public class AnnotatedElementUtils {
 	private static final Boolean CONTINUE = null;
 
 
+	/**
+	 * Build an adapted {@link AnnotatedElement} for the given annotations,
+	 * typically for use with other methods on {@link AnnotatedElementUtils}.
+	 * @param annotations the annotations to expose through the {@code AnnotatedElement}
+	 * @since 4.3
+	 */
+	public static AnnotatedElement forAnnotations(final Annotation... annotations) {
+		return new AnnotatedElement() {
+			@Override
+			@SuppressWarnings("unchecked")
+			public <T extends Annotation> T getAnnotation(Class<T> annotationClass) {
+				for (Annotation ann : annotations) {
+					if (ann.annotationType() == annotationClass) {
+						return (T) ann;
+					}
+				}
+				return null;
+			}
+			@Override
+			public Annotation[] getAnnotations() {
+				return annotations;
+			}
+			@Override
+			public Annotation[] getDeclaredAnnotations() {
+				return annotations;
+			}
+		};
+	}
+
 	/**
 	 * Get the fully qualified class names of all meta-annotation types
 	 * <em>present</em> on the annotation (of the specified {@code annotationType})