Provide hierarchy traversal support for getBeanNamesForAnnotation

Issue: SPR-15923

spring-beans/src/main/java/org/springframework/beans/factory/BeanFactoryUtils.java

@@ -16,6 +16,7 @@
 
 package org.springframework.beans.factory;
 
+import java.lang.annotation.Annotation;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedHashMap;
@@ -353,6 +354,37 @@ public static <T> T beanOfTypeIncludingAncestors(ListableBeanFactory lbf, Class<
 		return uniqueBean(type, beansOfType);
 	}
 
+	/**
+	 * Get all bean names whose {@code Class} has the supplied {@link Annotation}
+	 * type, including those defined in ancestor factories, without creating any bean
+	 * instances yet. Will return unique names in case of overridden bean definitions.
+	 * @param lbf the bean factory
+	 * @param annotationType the type of annotation to look for
+	 * @return the array of matching bean names, or an empty array if none
+	 * @since 5.0
+	 */
+	public static String[] beanNamesForAnnotationIncludingAncestors(
+			ListableBeanFactory lbf, Class<? extends Annotation> annotationType) {
+		Assert.notNull(lbf, "ListableBeanFactory must not be null");
+		String[] result = lbf.getBeanNamesForAnnotation(annotationType);
+		if (lbf instanceof HierarchicalBeanFactory) {
+			HierarchicalBeanFactory hbf = (HierarchicalBeanFactory) lbf;
+			if (hbf.getParentBeanFactory() instanceof ListableBeanFactory) {
+				String[] parentResult = beanNamesForAnnotationIncludingAncestors(
+						(ListableBeanFactory) hbf.getParentBeanFactory(), annotationType);
+				List<String> resultList = new ArrayList<>();
+				resultList.addAll(Arrays.asList(result));
+				for (String beanName : parentResult) {
+					if (!resultList.contains(beanName) && !hbf.containsLocalBean(beanName)) {
+						resultList.add(beanName);
+					}
+				}
+				result = StringUtils.toStringArray(resultList);
+			}
+		}
+		return result;
+	}
+
 	/**
 	 * Return a single bean of the given type or subtypes, also picking up beans
 	 * defined in ancestor bean factories if the current bean factory is a

spring-beans/src/test/java/org/springframework/beans/factory/BeanFactoryUtilsTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2017 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.
@@ -28,8 +28,10 @@
 import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
 import org.springframework.cglib.proxy.NoOp;
 import org.springframework.core.io.Resource;
+import org.springframework.tests.sample.beans.AnnotatedBean;
 import org.springframework.tests.sample.beans.ITestBean;
 import org.springframework.tests.sample.beans.IndexedTestBean;
+import org.springframework.tests.sample.beans.TestAnnotation;
 import org.springframework.tests.sample.beans.TestBean;
 import org.springframework.tests.sample.beans.factory.DummyFactory;
 import org.springframework.util.ObjectUtils;
@@ -91,8 +93,8 @@ public void testHierarchicalCountBeansWithOverride() throws Exception {
 		// Leaf count
 		assertTrue(this.listableBeanFactory.getBeanDefinitionCount() == 1);
 		// Count minus duplicate
-		assertTrue("Should count 7 beans, not " + BeanFactoryUtils.countBeansIncludingAncestors(this.listableBeanFactory),
-				BeanFactoryUtils.countBeansIncludingAncestors(this.listableBeanFactory) == 7);
+		assertTrue("Should count 8 beans, not " + BeanFactoryUtils.countBeansIncludingAncestors(this.listableBeanFactory),
+				BeanFactoryUtils.countBeansIncludingAncestors(this.listableBeanFactory) == 8);
 	}
 
 	@Test
@@ -265,6 +267,34 @@ public void testHierarchicalResolutionWithOverride() throws Exception {
 		assertEquals(this.listableBeanFactory.getBean("&testFactory2"), beans.get("&testFactory2"));
 	}
 
+	@Test
+	public void testHierarchicalNamesForAnnotationWithNoMatch() throws Exception {
+		List<String> names = Arrays.asList(
+				BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(this.listableBeanFactory, Override.class));
+		assertEquals(0, names.size());
+	}
+
+	@Test
+	public void testHierarchicalNamesForAnnotationWithMatchOnlyInRoot() throws Exception {
+		List<String> names = Arrays.asList(
+				BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(this.listableBeanFactory, TestAnnotation.class));
+		assertEquals(1, names.size());
+		assertTrue(names.contains("annotatedBean"));
+		// Distinguish from default ListableBeanFactory behavior
+		assertTrue(listableBeanFactory.getBeanNamesForAnnotation(TestAnnotation.class).length == 0);
+	}
+
+	@Test
+	public void testGetBeanNamesForAnnotationWithOverride() throws Exception {
+		AnnotatedBean annotatedBean = new AnnotatedBean();
+		this.listableBeanFactory.registerSingleton("anotherAnnotatedBean", annotatedBean);
+		List<String> names = Arrays.asList(
+				BeanFactoryUtils.beanNamesForAnnotationIncludingAncestors(this.listableBeanFactory, TestAnnotation.class));
+		assertEquals(2, names.size());
+		assertTrue(names.contains("annotatedBean"));
+		assertTrue(names.contains("anotherAnnotatedBean"));
+	}
+
 	@Test
 	public void testADependencies() {
 		String[] deps = this.dependentBeansFactory.getDependentBeans("a");

spring-beans/src/test/java/org/springframework/tests/sample/beans/AnnotatedBean.java

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2002-2017 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
+ *
+ *      http://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.tests.sample.beans;
+
+/**
+ * @author Stephane Nicoll
+ */
+@TestAnnotation
+public class AnnotatedBean {
+}

spring-beans/src/test/java/org/springframework/tests/sample/beans/TestAnnotation.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2002-2017 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
+ *
+ *      http://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.tests.sample.beans;
+
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+
+/**
+ * @author Stephane Nicoll
+ */
+@Retention(RetentionPolicy.RUNTIME)
+public @interface TestAnnotation {
+}

spring-beans/src/test/resources/org/springframework/beans/factory/BeanFactoryUtilsTests-root.xml

@@ -10,6 +10,8 @@
 
 	<bean id="indexedBean" class="org.springframework.tests.sample.beans.IndexedTestBean"/>
 
+	<bean id="annotatedBean" class="org.springframework.tests.sample.beans.AnnotatedBean"/>
+
 	<!-- Overridden by next factory -->
 	<bean id="test" class="org.springframework.tests.sample.beans.TestBean">
 		<property name="name"><value>custom</value></property>