abstractbeanfactory.java

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/*
 * Copyright 2002-2004 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.beans.factory.support;

import java.beans.PropertyEditor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeanWrapper;
import org.springframework.beans.BeanWrapperImpl;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanCreationException;
import org.springframework.beans.factory.BeanCurrentlyInCreationException;
import org.springframework.beans.factory.BeanDefinitionStoreException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.BeanIsAbstractException;
import org.springframework.beans.factory.BeanIsNotAFactoryException;
import org.springframework.beans.factory.BeanNotOfRequiredTypeException;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.FactoryBeanNotInitializedException;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.config.DestructionAwareBeanPostProcessor;
import org.springframework.util.Assert;

/**
 * Abstract superclass for BeanFactory implementations, implementing the
 * ConfigurableBeanFactory SPI interface. Does <i>not</i> assume a listable
 * bean factory: can therefore also be used as base class for bean factory
 * implementations which fetch bean definitions from a variety of backend
 * resources (where bean definition access is an expensive operation).
 *
 * <p>This class provides singleton/prototype determination, singleton cache,
 * aliases, FactoryBean handling, bean definition merging for child bean definitions,
 * and bean destruction (DisposableBean interface, custom destroy methods).
 * Furthermore, it can manage a bean factory hierarchy, through implementing the
 * HierarchicalBeanFactory interface (superinterface of ConfigurableBeanFactory).
 *
 * <p>The main template methods to be implemented by subclasses are
 * <code>getBeanDefinition</code> and <code>createBean</code>, retrieving a
 * bean definition for a given bean name or creating a bean instance for a
 * given bean definition. Default implementations for those can be found in
 * DefaultListableBeanFactory or AbstractAutowireCapableBeanFactory, respectively.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 15 April 2001
 * @see #getBeanDefinition
 * @see #createBean
 * @see org.springframework.beans.factory.HierarchicalBeanFactory
 * @see org.springframework.beans.factory.DisposableBean
 * @see RootBeanDefinition
 * @see ChildBeanDefinition
 * @see AbstractAutowireCapableBeanFactory#createBean
 * @see DefaultListableBeanFactory#getBeanDefinition
 */
public abstract class AbstractBeanFactory implements ConfigurableBeanFactory {

	/**
	 * Marker object to be temporarily registered in the singleton cache
	 * while instantiating a bean, to be able to detect circular references.
	 */
	private static final Object CURRENTLY_IN_CREATION = new Object();


	/** Logger available to subclasses */
	protected final Log logger = LogFactory.getLog(getClass());

	/** Parent bean factory, for bean inheritance support */
	private BeanFactory parentBeanFactory;

	/** Custom PropertyEditors to apply to the beans of this factory */
	private Map customEditors = new HashMap();

	/** BeanPostProcessors to apply in createBean */
	private final List beanPostProcessors = new ArrayList();

	private boolean hasDestructionAwareBeanPostProcessors;

	/** Map from alias to canonical bean name */
	private final Map aliasMap = Collections.synchronizedMap(new HashMap());

	/** Cache of singletons: bean name --> bean instance */
	private final Map singletonCache = Collections.synchronizedMap(new HashMap());

	/** Disposable bean instances: bean name --> disposable instance */
	private final Map disposableBeans = Collections.synchronizedMap(new HashMap());

	/** Map between dependent bean names: bean name --> dependent bean name */
	private final Map dependentBeanMap = Collections.synchronizedMap(new HashMap());


	/**
	 * Create a new AbstractBeanFactory.
	 */
	public AbstractBeanFactory() {
	}

	/**
	 * Create a new AbstractBeanFactory with the given parent.
	 * @param parentBeanFactory parent bean factory, or null if none
	 * @see #getBean
	 */
	public AbstractBeanFactory(BeanFactory parentBeanFactory) {
		this.parentBeanFactory = parentBeanFactory;
	}


	//---------------------------------------------------------------------
	// Implementation of BeanFactory interface
	//---------------------------------------------------------------------

	public Object getBean(String name) throws BeansException {
		return getBean(name, null, null);
	}
		
	public Object getBean(String name, Class requiredType) throws BeansException {
		return getBean(name, requiredType, null);
	}

	/**
	 * Return the bean with the given name,
	 * checking the parent bean factory if not found.
	 * @param name the name of the bean to retrieve
	 * @param args arguments to use if creating a prototype using explicit arguments to a
	 * static factory method. It is invalid to use a non-null args value in any other case.
	 */
	public Object getBean(String name, Object[] args) throws BeansException {
		return getBean(name, null, args);
	}

	/**
	 * Return the bean with the given name,
	 * checking the parent bean factory if not found.
	 * @param name the name of the bean to retrieve
	 * @param requiredType the required type of the bean to retrieve
	 * @param args arguments to use if creating a prototype using explicit arguments to a
	 * static factory method. It is invalid to use a non-null args value in any other case.
	 * TODO: We could consider supporting this for constructor args also, but it's really a
	 * corner case required for AspectJ integration.
	 */
	public Object getBean(String name, Class requiredType, Object[] args) throws BeansException {
		String beanName = transformedBeanName(name);
		Object bean = null;

		// Eagerly check singleton cache for manually registered singletons.
		Object sharedInstance = this.singletonCache.get(beanName);
		if (sharedInstance != null) {
			if (sharedInstance == CURRENTLY_IN_CREATION) {
				throw new BeanCurrentlyInCreationException(beanName);
			}
			if (logger.isDebugEnabled()) {
				logger.debug("Returning cached instance of singleton bean '" + beanName + "'");
			}
			bean = getObjectForSharedInstance(name, sharedInstance);
		}

		else {
			// Check if bean definition exists in this factory.
			RootBeanDefinition mergedBeanDefinition = null;
			try {
				mergedBeanDefinition = getMergedBeanDefinition(beanName, false);
			}
			catch (NoSuchBeanDefinitionException ex) {
				// Not found -> check parent.
				if (this.parentBeanFactory instanceof AbstractBeanFactory) {
					// Delegation to parent with args only possible for AbstractBeanFactory.
					return ((AbstractBeanFactory) this.parentBeanFactory).getBean(name, requiredType, args);
				}
				else if (this.parentBeanFactory != null && args == null) {
					// No args -> delegate to standard getBean method.
					return this.parentBeanFactory.getBean(name, requiredType);
				}
				throw ex;
			}

			checkMergedBeanDefinition(mergedBeanDefinition, beanName, requiredType, args);

			// Create bean instance.
			if (mergedBeanDefinition.isSingleton()) {
				synchronized (this.singletonCache) {
					// re-check singleton cache within synchronized block
					sharedInstance = this.singletonCache.get(beanName);
					if (sharedInstance == null) {
						if (logger.isInfoEnabled()) {
							logger.info("Creating shared instance of singleton bean '" + beanName + "'");
						}
						this.singletonCache.put(beanName, CURRENTLY_IN_CREATION);
						try {
							sharedInstance = createBean(beanName, mergedBeanDefinition, args);
							this.singletonCache.put(beanName, sharedInstance);
						}
						catch (BeansException ex) {
							this.singletonCache.remove(beanName);
							throw ex;
						}
					}
				}
				bean = getObjectForSharedInstance(name, sharedInstance);
			}
			else {
				// It's a prototype -> create a new instance.
				bean = createBean(name, mergedBeanDefinition, args);
			}
		}

		// Check if required type matches the type of the actual bean instance.
		if (requiredType != null && !requiredType.isAssignableFrom(bean.getClass())) {
			throw new BeanNotOfRequiredTypeException(name, requiredType, bean.getClass());
		}
		return bean;
	}

	public boolean containsBean(String name) {
		String beanName = transformedBeanName(name);
		if (this.singletonCache.containsKey(beanName)) {
			return true;
		}
		if (containsBeanDefinition(beanName)) {
			return true;
		}
		else {
			// Not found -> check parent.
			if (this.parentBeanFactory != null) {
				return this.parentBeanFactory.containsBean(name);
			}
			else {
				return false;
			}
		}
	}

	public boolean isSingleton(String name) throws NoSuchBeanDefinitionException {
		String beanName = transformedBeanName(name);
		try {
			Class beanClass = null;
			boolean singleton = true;

			Object beanInstance = this.singletonCache.get(beanName);
			if (beanInstance == CURRENTLY_IN_CREATION) {
				throw new BeanCurrentlyInCreationException(beanName);
			}
			if (beanInstance != null) {
				beanClass = beanInstance.getClass();
				singleton = true;
			}
			else {
				RootBeanDefinition bd = getMergedBeanDefinition(beanName, false);
				if (bd.hasBeanClass()) {
					beanClass = bd.getBeanClass();
				}
				singleton = bd.isSingleton();
			}

			// In case of FactoryBean, return singleton status of created object if not a dereference.
			if (beanClass != null && FactoryBean.class.isAssignableFrom(beanClass) &&
					!isFactoryDereference(name)) {
				FactoryBean factoryBean = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName);
				return factoryBean.isSingleton();
			}
			return singleton;
		}
		catch (NoSuchBeanDefinitionException ex) {
			// Not found -> check parent.
			if (this.parentBeanFactory != null) {
				return this.parentBeanFactory.isSingleton(name);
			}
			throw ex;
		}
	}

	public Class getType(String name) throws NoSuchBeanDefinitionException {
		String beanName = transformedBeanName(name);
		try {
			Class beanClass = null;

			// Check manually registered singletons.
			Object beanInstance = this.singletonCache.get(beanName);
			if (beanInstance == CURRENTLY_IN_CREATION) {
				throw new BeanCurrentlyInCreationException(beanName);
			}
			if (beanInstance != null) {
				beanClass = beanInstance.getClass();
			}
			
			else {
				// OK, let's assume it's a bean definition.
				RootBeanDefinition mergedBeanDefinition = getMergedBeanDefinition(beanName, false);

				// Return "undeterminable" for beans without class or with factory method.
				if (!mergedBeanDefinition.hasBeanClass() || mergedBeanDefinition.getFactoryMethodName() != null) {
					return null;
				}

				beanClass = mergedBeanDefinition.getBeanClass();
			}

			// Check bean class whether we're dealing with a FactoryBean.
			if (FactoryBean.class.isAssignableFrom(beanClass) && !isFactoryDereference(name)) {
				// If it's a FactoryBean, we want to look at what it creates, not the factory class.
				FactoryBean factoryBean = (FactoryBean) getBean(FACTORY_BEAN_PREFIX + beanName);
				return factoryBean.getObjectType();
			}
			return beanClass;
		}
		catch (NoSuchBeanDefinitionException ex) {
			// Not found -> check parent.
			if (this.parentBeanFactory != null) {