@import allows for importing regular component classes as well

Issue: SPR-11740

Author: jhoeller

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

@@ -35,8 +35,6 @@
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.groovy.GroovyBeanDefinitionReader;
-import org.springframework.beans.factory.parsing.Location;
-import org.springframework.beans.factory.parsing.Problem;
 import org.springframework.beans.factory.parsing.ProblemReporter;
 import org.springframework.beans.factory.parsing.SourceExtractor;
 import org.springframework.beans.factory.support.AbstractBeanDefinitionReader;
@@ -160,22 +158,18 @@ private void registerBeanDefinitionForImportedConfigurationClass(ConfigurationCl
 		AnnotationMetadata metadata = configClass.getMetadata();
 		AnnotatedGenericBeanDefinition configBeanDef = new AnnotatedGenericBeanDefinition(metadata);
 
-		if (ConfigurationClassUtils.checkConfigurationClassCandidate(configBeanDef, this.metadataReaderFactory)) {
-			ScopeMetadata scopeMetadata = scopeMetadataResolver.resolveScopeMetadata(configBeanDef);
-			configBeanDef.setScope(scopeMetadata.getScopeName());
-			String configBeanName = this.importBeanNameGenerator.generateBeanName(configBeanDef, this.registry);
-			AnnotationConfigUtils.processCommonDefinitionAnnotations(configBeanDef, metadata);
-			BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(configBeanDef, configBeanName);
-			definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
-			this.registry.registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition());
-			configClass.setBeanName(configBeanName);
-			if (logger.isDebugEnabled()) {
-				logger.debug(String.format("Registered bean definition for imported @Configuration class %s", configBeanName));
-			}
-		}
-		else {
-			this.problemReporter.error(
-					new InvalidConfigurationImportProblem(metadata.getClassName(), configClass.getResource(), metadata));
+		ScopeMetadata scopeMetadata = scopeMetadataResolver.resolveScopeMetadata(configBeanDef);
+		configBeanDef.setScope(scopeMetadata.getScopeName());
+		String configBeanName = this.importBeanNameGenerator.generateBeanName(configBeanDef, this.registry);
+		AnnotationConfigUtils.processCommonDefinitionAnnotations(configBeanDef, metadata);
+
+		BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(configBeanDef, configBeanName);
+		definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
+		this.registry.registerBeanDefinition(definitionHolder.getBeanName(), definitionHolder.getBeanDefinition());
+		configClass.setBeanName(configBeanName);
+
+		if (logger.isDebugEnabled()) {
+			logger.debug("Registered bean definition for imported class '" + configBeanName + "'");
 		}
 	}
 
@@ -422,21 +416,6 @@ public ConfigurationClassBeanDefinition cloneBeanDefinition() {
 	}
 
 
-	/**
-	 * Configuration classes must be annotated with {@link Configuration @Configuration} or
-	 * declare at least one {@link Bean @Bean} method.
-	 */
-	private static class InvalidConfigurationImportProblem extends Problem {
-
-		public InvalidConfigurationImportProblem(String className, Resource resource, AnnotationMetadata metadata) {
-			super(String.format("%s was @Import'ed but is not annotated with @Configuration " +
-					"nor does it declare any @Bean methods; it does not implement ImportSelector " +
-					"or extend ImportBeanDefinitionRegistrar. Update the class to meet one of these requirements " +
-					"or do not attempt to @Import it.", className), new Location(resource, metadata));
-		}
-	}
-
-
 	/**
 	 * Evaluate {@code @Conditional} annotations, tracking results and taking into
 	 * account 'imported by'.

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 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.
@@ -26,22 +26,23 @@
  * Indicates one or more {@link Configuration @Configuration} classes to import.
  *
  * <p>Provides functionality equivalent to the {@code <import/>} element in Spring XML.
- * Only supported for classes annotated with {@code @Configuration} or declaring at least
- * one {@link Bean @Bean} method, as well as {@link ImportSelector} and
- * {@link ImportBeanDefinitionRegistrar} implementations.
+ * Allows for importing {@code @Configuration} classes, {@link ImportSelector} and
+ * {@link ImportBeanDefinitionRegistrar} implementations, as well as regular component
+ * classes (as of 4.2; analogous to {@link AnnotationConfigApplicationContext#register}).
  *
- * <p>{@code @Bean} definitions declared in imported {@code @Configuration} classes
- * should be accessed by using {@link org.springframework.beans.factory.annotation.Autowired @Autowired}
+ * <p>{@code @Bean} definitions declared in imported {@code @Configuration} classes should be
+ * accessed by using {@link org.springframework.beans.factory.annotation.Autowired @Autowired}
  * injection. Either the bean itself can be autowired, or the configuration class instance
- * declaring the bean can be autowired. The latter approach allows for explicit,
- * IDE-friendly navigation between {@code @Configuration} class methods.
+ * declaring the bean can be autowired. The latter approach allows for explicit, IDE-friendly
+ * navigation between {@code @Configuration} class methods.
  *
  * <p>May be declared at the class level or as a meta-annotation.
  *
  * <p>If XML or other non-{@code @Configuration} bean definition resources need to be
- * imported, use {@link ImportResource @ImportResource}
+ * imported, use the {@link ImportResource @ImportResource} annotation instead.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  * @since 3.0
  * @see Configuration
  * @see ImportSelector
@@ -53,8 +54,9 @@
 public @interface Import {
 
 	/**
-	 * The @{@link Configuration}, {@link ImportSelector} and/or
-	 * {@link ImportBeanDefinitionRegistrar} classes to import.
+	 * @{@link Configuration}, {@link ImportSelector}, {@link ImportBeanDefinitionRegistrar}
+	 * or regular component classes to import.
 	 */
 	Class<?>[] value();
+
 }

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 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.
@@ -18,13 +18,13 @@
 
 import org.junit.Test;
 
-import org.springframework.beans.factory.parsing.BeanDefinitionParsingException;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.ConfigurationClassPostProcessor;
+import org.springframework.context.annotation.DependsOn;
 import org.springframework.context.annotation.Import;
 import org.springframework.tests.sample.beans.ITestBean;
 import org.springframework.tests.sample.beans.TestBean;
@@ -36,6 +36,7 @@
  * System tests for {@link Import} annotation support.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  */
 public class ImportTests {
 
@@ -52,6 +53,11 @@ private DefaultListableBeanFactory processConfigurationClasses(Class<?>... class
 	private void assertBeanDefinitionCount(int expectedCount, Class<?>... classes) {
 		DefaultListableBeanFactory beanFactory = processConfigurationClasses(classes);
 		assertThat(beanFactory.getBeanDefinitionCount(), equalTo(expectedCount));
+		beanFactory.preInstantiateSingletons();
+		for (Class<?> clazz : classes) {
+			beanFactory.getBean(clazz);
+		}
+
 	}
 
 	@Test
@@ -118,7 +124,6 @@ public ITestBean three() {
 	public void testImportAnnotationWithTwoLevelRecursion() {
 		int configClasses = 2;
 		int beansInClasses = 3;
-
 		assertBeanDefinitionCount((configClasses + beansInClasses), AppConfig.class);
 	}
 
@@ -149,10 +154,9 @@ public ITestBean dataSourceA() {
 
 	@Test
 	public void testImportAnnotationWithThreeLevelRecursion() {
-		int configClasses = 3;
+		int configClasses = 4;
 		int beansInClasses = 5;
-
-		assertBeanDefinitionCount((configClasses + beansInClasses), FirstLevel.class);
+		assertBeanDefinitionCount(configClasses + beansInClasses, FirstLevel.class);
 	}
 
 	// ------------------------------------------------------------------------
@@ -161,9 +165,7 @@ public void testImportAnnotationWithThreeLevelRecursion() {
 	public void testImportAnnotationWithMultipleArguments() {
 		int configClasses = 3;
 		int beansInClasses = 3;
-
-		assertBeanDefinitionCount((configClasses + beansInClasses),
-				WithMultipleArgumentsToImportAnnotation.class);
+		assertBeanDefinitionCount((configClasses + beansInClasses), WithMultipleArgumentsToImportAnnotation.class);
 	}
 
 
@@ -179,7 +181,7 @@ public void testImportAnnotationWithMultipleArgumentsResultingInOverriddenBeanDe
 	}
 
 	@Configuration
-	@Import( { Foo1.class, Foo2.class })
+	@Import({Foo1.class, Foo2.class})
 	static class WithMultipleArgumentsThatWillCauseDuplication {
 	}
 
@@ -205,7 +207,6 @@ public ITestBean foo() {
 	public void testImportAnnotationOnInnerClasses() {
 		int configClasses = 2;
 		int beansInClasses = 2;
-
 		assertBeanDefinitionCount((configClasses + beansInClasses), OuterConfig.InnerConfig.class);
 	}
 
@@ -246,7 +247,7 @@ public TestBean m() {
 	}
 
 	@Configuration
-	@Import(ThirdLevel.class)
+	@Import({ThirdLevel.class, InitBean.class})
 	static class SecondLevel {
 		@Bean
 		public TestBean n() {
@@ -255,7 +256,12 @@ public TestBean n() {
 	}
 
 	@Configuration
+	@DependsOn("org.springframework.context.annotation.configuration.ImportTests$InitBean")
 	static class ThirdLevel {
+		public ThirdLevel() {
+			assertTrue(InitBean.initialized);
+		}
+
 		@Bean
 		public ITestBean thirdLevelA() {
 			return new TestBean();
@@ -272,8 +278,16 @@ public ITestBean thirdLevelC() {
 		}
 	}
 
+	static class InitBean {
+		public static boolean initialized = false;
+
+		public InitBean() {
+			initialized = true;
+		}
+	}
+
 	@Configuration
-	@Import( { LeftConfig.class, RightConfig.class })
+	@Import({LeftConfig.class, RightConfig.class})
 	static class WithMultipleArgumentsToImportAnnotation {
 		@Bean
 		public TestBean m() {
@@ -299,9 +313,11 @@ public ITestBean right() {
 
 	// ------------------------------------------------------------------------
 
-	@Test(expected=BeanDefinitionParsingException.class)
-	public void testImportNonConfigurationAnnotationClassCausesError() {
-		processConfigurationClasses(ConfigAnnotated.class);
+	@Test
+	public void testImportNonConfigurationAnnotationClass() {
+		int configClasses = 2;
+		int beansInClasses = 0;
+		assertBeanDefinitionCount((configClasses + beansInClasses), ConfigAnnotated.class);
 	}
 
 	@Configuration

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2013 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.
@@ -19,7 +19,6 @@
 import org.junit.Test;
 
 import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.beans.factory.parsing.BeanDefinitionParsingException;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
@@ -35,10 +34,10 @@
  * Unit tests cornering the bug exposed in SPR-6779.
  *
  * @author Chris Beams
+ * @author Juergen Hoeller
  */
 public class ImportedConfigurationClassEnhancementTests {
 
-
 	@Test
 	public void autowiredConfigClassIsEnhancedWhenImported() {
 		autowiredConfigClassIsEnhanced(ConfigThatDoesImport.class);
@@ -77,30 +76,42 @@ private void autowiredConfigClassBeanMethodsRespectScoping(Class<?>... configCla
 	}
 
 
-	@Test(expected=BeanDefinitionParsingException.class)
+	@Test
 	public void importingNonConfigurationClassCausesBeanDefinitionParsingException() {
-		new AnnotationConfigApplicationContext(ConfigThatImportsNonConfigClass.class);
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(ConfigThatImportsNonConfigClass.class);
+		ConfigThatImportsNonConfigClass config = ctx.getBean(ConfigThatImportsNonConfigClass.class);
+		assertSame(ctx.getBean(TestBean.class), config.testBean);
 	}
-}
 
-@Configuration
-class ConfigToBeAutowired {
-	public @Bean TestBean testBean() {
-		return new TestBean();
+
+
+	@Configuration
+	static class ConfigToBeAutowired {
+
+		public @Bean TestBean testBean() {
+			return new TestBean();
+		}
 	}
-}
 
-class Config {
-	@Autowired ConfigToBeAutowired autowiredConfig;
-}
+	static class Config {
 
-@Import(ConfigToBeAutowired.class)
-@Configuration
-class ConfigThatDoesImport extends Config { }
+		@Autowired ConfigToBeAutowired autowiredConfig;
+	}
+
+	@Import(ConfigToBeAutowired.class)
+	@Configuration
+	static class ConfigThatDoesImport extends Config {
+	}
+
+	@Configuration
+	static class ConfigThatDoesNotImport extends Config {
+	}
+
+	@Configuration
+	@Import(TestBean.class)
+	static class ConfigThatImportsNonConfigClass {
 
-@Configuration
-class ConfigThatDoesNotImport extends Config { }
+		@Autowired TestBean testBean;
+	}
 
-@Configuration
-@Import(TestBean.class)
-class ConfigThatImportsNonConfigClass { }
+}