Introduce ImportAware interface

@Configuration classes may implement ImportAware in order to be injected
with the AnnotationMetadata of their @Import'ing class.

Includes the introduction of a new PriorityOrdered
ImportAwareBeanPostProcessor that handles injection of the
importing class metadata.

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

@@ -19,6 +19,7 @@ package org.springframework.context.annotation;
 import java.io.IOException;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashMap;
 import java.util.Iterator;
 import java.util.LinkedHashSet;
 import java.util.List;
@@ -62,7 +63,7 @@ class ConfigurationClassParser {
 
 	private final ProblemReporter problemReporter;
 
-	private final Stack<ConfigurationClass> importStack = new ImportStack();
+	private final ImportStack importStack = new ImportStack();
 
 	private final Set<ConfigurationClass> configurationClasses =
 		new LinkedHashSet<ConfigurationClass>();
@@ -168,6 +169,7 @@ class ConfigurationClassParser {
 		else {
 			this.importStack.push(configClass);
 			for (String classToImport : classesToImport) {
+				this.importStack.registerImport(configClass.getMetadata().getClassName(), classToImport);
 				MetadataReader reader = this.metadataReaderFactory.getMetadataReader(classToImport);
 				processConfigurationClass(new ConfigurationClass(reader, null));
 			}
@@ -189,9 +191,28 @@ class ConfigurationClassParser {
 		return this.configurationClasses;
 	}
 
+	public ImportRegistry getImportRegistry() {
+		return this.importStack;
+	}
+
+
+	interface ImportRegistry {
+		String getImportingClassFor(String importedClass);
+	}
+
 
 	@SuppressWarnings("serial")
-	private static class ImportStack extends Stack<ConfigurationClass> {
+	private static class ImportStack extends Stack<ConfigurationClass> implements ImportRegistry {
+
+		private Map<String, String> imports = new HashMap<String, String>();
+
+		public String getImportingClassFor(String importedClass) {
+			return imports.get(importedClass);
+		}
+
+		public void registerImport(String importingClass, String importedClass) {
+			imports.put(importedClass, importingClass);
+		}
 
 		/**
 		 * Simplified contains() implementation that tests to see if any {@link ConfigurationClass}

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

@@ -24,27 +24,38 @@ import java.util.Set;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanDefinitionStoreException;
+import org.springframework.beans.factory.BeanFactory;
+import org.springframework.beans.factory.BeanFactoryAware;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanDefinitionHolder;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
+import org.springframework.beans.factory.config.BeanPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.beans.factory.config.SingletonBeanRegistry;
 import org.springframework.beans.factory.parsing.FailFastProblemReporter;
 import org.springframework.beans.factory.parsing.PassThroughSourceExtractor;
 import org.springframework.beans.factory.parsing.ProblemReporter;
 import org.springframework.beans.factory.parsing.SourceExtractor;
 import org.springframework.beans.factory.support.AbstractBeanDefinition;
+import org.springframework.beans.factory.support.BeanDefinitionReaderUtils;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
+import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.context.EnvironmentAware;
 import org.springframework.context.ResourceLoaderAware;
+import org.springframework.context.annotation.ConfigurationClassParser.ImportRegistry;
 import org.springframework.core.Ordered;
+import org.springframework.core.PriorityOrdered;
 import org.springframework.core.env.Environment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.ResourceLoader;
+import org.springframework.core.type.AnnotationMetadata;
 import org.springframework.core.type.classreading.CachingMetadataReaderFactory;
 import org.springframework.core.type.classreading.MetadataReaderFactory;
+import org.springframework.core.type.classreading.SimpleMetadataReaderFactory;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 
@@ -147,6 +158,7 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 	 * Derive further bean definitions from the configuration classes in the registry.
 	 */
 	public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) {
+		BeanDefinitionReaderUtils.registerWithGeneratedName(new RootBeanDefinition(ImportAwareBeanPostProcessor.class), registry);
 		if (this.postProcessBeanDefinitionRegistryCalled) {
 			throw new IllegalStateException(
 					"postProcessBeanDefinitionRegistry already called for this post-processor");
@@ -231,6 +243,13 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 
 		// Read the model and create bean definitions based on its content
 		reader.loadBeanDefinitions(parser.getConfigurationClasses());
+
+		// Register the ImportRegistry as a bean in order to support ImportAware @Configuration classes
+		if (registry instanceof SingletonBeanRegistry) {
+			if (!((SingletonBeanRegistry) registry).containsSingleton("importRegistry")) {
+				((SingletonBeanRegistry) registry).registerSingleton("importRegistry", parser.getImportRegistry());
+			}
+		}
 	}
 
 	/**
@@ -278,4 +297,41 @@ public class ConfigurationClassPostProcessor implements BeanDefinitionRegistryPo
 		}
 	}
 
+
+	private static class ImportAwareBeanPostProcessor implements PriorityOrdered, BeanFactoryAware, BeanPostProcessor {
+
+		private BeanFactory beanFactory;
+
+		public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
+			this.beanFactory = beanFactory;
+		}
+
+		public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
+			if (bean instanceof ImportAware) {
+				ImportRegistry importRegistry = beanFactory.getBean(ImportRegistry.class);
+				String importingClass = importRegistry.getImportingClassFor(bean.getClass().getSuperclass().getName());
+				if (importingClass != null) {
+					try {
+						AnnotationMetadata metadata = new SimpleMetadataReaderFactory().getMetadataReader(importingClass).getAnnotationMetadata();
+						((ImportAware) bean).setImportMetadata(metadata);
+					} catch (IOException ex) {
+						// should never occur -> at this point we know the class is present anyway
+						throw new IllegalStateException(ex);
+					}
+				}
+				else {
+					// no importing class was found
+				}
+			}
+			return bean;
+		}
+
+		public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
+			return bean;
+		}
+
+		public int getOrder() {
+			return Ordered.HIGHEST_PRECEDENCE;
+		}
+	}
 }

org.springframework.context/src/main/java/org/springframework/context/annotation/ImportAware.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2002-2011 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 org.springframework.beans.factory.Aware;
+import org.springframework.core.type.AnnotationMetadata;
+
+/**
+ * Interface to be implemented by any @{@link Configuration} class that wishes
+ * to be injected with the {@link AnnotationMetadata} of the @{@code Configuration}
+ * class that imported it. Useful in conjunction with annotations that
+ * use @{@link Import} as a meta-annotation.
+ *
+ * @author Chris Beams
+ * @since 3.1
+ */
+public interface ImportAware extends Aware {
+
+	/**
+	 * Set the annotation metadata of the importing @{@code Configuration} class.
+	 */
+	void setImportMetadata(AnnotationMetadata importMetadata);
+
+}