ComponentScan annotation is repeatable now

Issue: SPR-13151

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

@@ -18,6 +18,7 @@ package org.springframework.context.annotation;
 
 import java.lang.annotation.Documented;
 import java.lang.annotation.ElementType;
+import java.lang.annotation.Repeatable;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -54,6 +55,7 @@ import org.springframework.core.type.filter.TypeFilter;
 @Retention(RetentionPolicy.RUNTIME)
 @Target(ElementType.TYPE)
 @Documented
+@Repeatable(ComponentScans.class)
 public @interface ComponentScan {
 
 	/**

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

@@ -0,0 +1,44 @@
+/*
+ * 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.
+ * 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.context.annotation;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Container annotation that aggregates several {@link ComponentScan} annotations.
+ *
+ * <p>Can be used natively, declaring several nested {@link ComponentScan} annotations.
+ * Can also be used in conjunction with Java 8's support for repeatable annotations,
+ * where {@link ComponentScan} can simply be declared several times on the same method,
+ * implicitly generating this container annotation.
+ *
+ * @author Juergen Hoeller
+ * @since 4.3
+ * @see ComponentScan
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target(ElementType.TYPE)
+@Documented
+public @interface ComponentScans {
+
+	ComponentScan[] value();
+
+}

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

@@ -260,8 +260,10 @@ class ConfigurationClassParser {
 		}
 
 		// Process any @ComponentScan annotations
-		AnnotationAttributes componentScan = AnnotationConfigUtils.attributesFor(sourceClass.getMetadata(), ComponentScan.class);
-		if (componentScan != null && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
+		Set<AnnotationAttributes> componentScans = AnnotationConfigUtils.attributesForRepeatable(
+				sourceClass.getMetadata(), ComponentScans.class, ComponentScan.class);
+		if (!componentScans.isEmpty() && !this.conditionEvaluator.shouldSkip(sourceClass.getMetadata(), ConfigurationPhase.REGISTER_BEAN)) {
+			for (AnnotationAttributes componentScan : componentScans) {
 				// The config class is annotated with @ComponentScan -> perform the scan immediately
 				Set<BeanDefinitionHolder> scannedBeanDefinitions =
 						this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());
@@ -272,6 +274,7 @@ class ConfigurationClassParser {
 					}
 				}
 			}
+		}
 
 		// Process any @Import annotations
 		processImports(configClass, sourceClass, getImports(sourceClass), true);

spring-context/src/test/java/org/springframework/context/annotation/ComponentScanAnnotationIntegrationTests.java

@@ -147,7 +147,7 @@ public class ComponentScanAnnotationIntegrationTests {
 	@Test
 	public void withCustomBeanNameGenerator() {
 		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
-		ctx.register(ComponentScanWithBeanNameGenenerator.class);
+		ctx.register(ComponentScanWithBeanNameGenerator.class);
 		ctx.refresh();
 		assertThat(ctx.containsBean("custom_fooServiceImpl"), is(true));
 		assertThat(ctx.containsBean("fooServiceImpl"), is(false));
@@ -159,6 +159,14 @@ public class ComponentScanAnnotationIntegrationTests {
 		// custom scope annotation makes the bean prototype scoped. subsequent calls
 		// to getBean should return distinct instances.
 		assertThat(ctx.getBean(CustomScopeAnnotationBean.class), not(sameInstance(ctx.getBean(CustomScopeAnnotationBean.class))));
+		assertThat(ctx.containsBean("scannedComponent"), is(false));
+	}
+
+	@Test
+	public void multiComponentScan() {
+		AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(MultiComponentScan.class);
+		assertThat(ctx.getBean(CustomScopeAnnotationBean.class), not(sameInstance(ctx.getBean(CustomScopeAnnotationBean.class))));
+		assertThat(ctx.containsBean("scannedComponent"), is(true));
 	}
 
 	@Test
@@ -241,7 +249,8 @@ public class ComponentScanAnnotationIntegrationTests {
 	@ComponentScan
 	@Retention(RetentionPolicy.RUNTIME)
 	@Target(ElementType.TYPE)
-	public static @interface ComposedConfiguration {
+	public @interface ComposedConfiguration {
+
 		String[] basePackages() default {};
 	}
 
@@ -255,6 +264,7 @@ public class ComponentScanAnnotationIntegrationTests {
 @Configuration
 @ComponentScan(basePackageClasses = example.scannable._package.class)
 class ComponentScanAnnotatedConfig {
+
 	@Bean
 	public TestBean testBean() {
 		return new TestBean();
@@ -264,6 +274,7 @@ class ComponentScanAnnotatedConfig {
 @Configuration
 @ComponentScan("example.scannable")
 class ComponentScanAnnotatedConfig_WithValueAttribute {
+
 	@Bean
 	public TestBean testBean() {
 		return new TestBean();
@@ -272,13 +283,16 @@ class ComponentScanAnnotatedConfig_WithValueAttribute {
 
 @Configuration
 @ComponentScan
-class ComponentScanWithNoPackagesConfig {}
+class ComponentScanWithNoPackagesConfig {
+}
 
 @Configuration
 @ComponentScan(basePackages = "example.scannable", nameGenerator = MyBeanNameGenerator.class)
-class ComponentScanWithBeanNameGenenerator {}
+class ComponentScanWithBeanNameGenerator {
+}
 
 class MyBeanNameGenerator extends AnnotationBeanNameGenerator {
+
 	@Override
 	public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
 		return "custom_" + super.generateBeanName(definition, registry);
@@ -287,9 +301,17 @@ class MyBeanNameGenerator extends AnnotationBeanNameGenerator {
 
 @Configuration
 @ComponentScan(basePackages = "example.scannable_scoped", scopeResolver = MyScopeMetadataResolver.class)
-class ComponentScanWithScopeResolver {}
+class ComponentScanWithScopeResolver {
+}
+
+@Configuration
+@ComponentScan(basePackages = "example.scannable_scoped", scopeResolver = MyScopeMetadataResolver.class)
+@ComponentScan(basePackages = "example.scannable_implicitbasepackage")
+class MultiComponentScan {
+}
 
 class MyScopeMetadataResolver extends AnnotationScopeMetadataResolver {
+
 	MyScopeMetadataResolver() {
 		this.scopeAnnotationType = MyScope.class;
 	}
@@ -304,6 +326,7 @@ class MyScopeMetadataResolver extends AnnotationScopeMetadataResolver {
 		excludeFilters = @Filter(type = FilterType.ASSIGNABLE_TYPE, classes = ComponentScanWithCustomTypeFilter.class),
 		lazyInit = true)
 class ComponentScanWithCustomTypeFilter {
+
 	@Bean
 	@SuppressWarnings({ "rawtypes", "serial", "unchecked" })
 	public static CustomAutowireConfigurer customAutowireConfigurer() {