proxyfactorybean.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

/*
 * 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.aop.framework;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.aopalliance.aop.Advice;
import org.aopalliance.intercept.Interceptor;

import org.springframework.aop.Advisor;
import org.springframework.aop.TargetSource;
import org.springframework.aop.framework.adapter.AdvisorAdapterRegistry;
import org.springframework.aop.framework.adapter.GlobalAdvisorAdapterRegistry;
import org.springframework.aop.framework.adapter.UnknownAdviceTypeException;
import org.springframework.aop.support.AopUtils;
import org.springframework.aop.target.SingletonTargetSource;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.FactoryBean;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.core.OrderComparator;

/**
 * FactoryBean implementation for use to source AOP proxies from a Spring BeanFactory.
 *
 * <p>Interceptors and Advisors are identified by a list of bean names in the current
 * bean factory. These beans should be of type Interceptor or Advisor. The last entry
 * in the list can be the name of any bean in the factory. If it's neither an
 * Interceptor nor an Advisor, a new SingletonTargetSource is added to wrap it. If it;s
 * a TargetSource, it is used as this proxy factory's TargetSource. It's normally preferred
 * to use the "targetSource" property to set the TargetSource. It is not possible to use
 * both the targetSource property and an interceptor name: this is treated as a
 * configuration error.
 *
 * <p>Global interceptors and advisors can be added at the factory level. The specified
 * ones are expanded in an interceptor list where an "xxx*" entry is included in the
 * list, matching the given prefix with the bean names (e.g. "global*" would match
 * both "globalBean1" and "globalBean2", "*" all defined interceptors). The matching
 * interceptors get applied according to their returned order value, if they
 * implement the Ordered interface. An interceptor name list may not conclude
 * with a global "xxx*" pattern, as global interceptors cannot invoke targets.
 *
 * <p>Creates a J2SE proxy when proxy interfaces are given, a CGLIB proxy for the
 * actual target class if not. Note that the latter will only work if the target class
 * does not have final methods, as a dynamic subclass will be created at runtime.
 *
 * <p>It's possible to cast a proxy obtained from this factory to <code>Advised</code>, or to
 * obtain the ProxyFactoryBean reference and programmatically manipulate it.
 * This won't work for existing prototype references, which are independent. However,
 * it will work for prototypes subsequently obtained from the factory. Changes to
 * interception will work immediately on singletons (including existing references).
 * However, to change interfaces or target it's necessary to obtain a new instance
 * from the factory. This means that singleton instances obtained from the factory
 * do not have the same object identity. However, they do have the same interceptors
 * and target, and changing any reference will change all objects.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @see #setInterceptorNames
 * @see #setProxyInterfaces
 * @see org.aopalliance.intercept.MethodInterceptor
 * @see org.springframework.aop.framework.Advised
 * @see org.springframework.aop.target.SingletonTargetSource
 */
public class ProxyFactoryBean extends AdvisedSupport
    implements FactoryBean, BeanFactoryAware, AdvisedSupportListener {
	
	/*
	 * Implementation notes. There are two cases of usage of this class:
	 * usage as a singleton, when only one object will be created, and usage
	 * as a prototype, when the FactoryBean.getObject() method must return an 
	 * independent proxy on each invocation. In the latter case, a distinct instance of
	 * any non-singleton Advisors or Advices must be used, as well as a distinct
	 * target/TargetSource instance if the target is a prototype and is specified in the
	 * interceptorNames list, rather than using the target or targetSource property. 
	 * 
	 * If this factory is used as a singleton, the advice chain in this class is used
	 * and all Advisors/Advices are materialized when the singleton instance is created.
	 * If it's a prototype, new AdvisedSupport instances are created with
	 * a copy of the advice chain to create each proxy and support independent
	 * manipulation of advice. Any advisor/advice bean names that that are prototypes
	 * are replaced by placeholders in the advisor chain held in this class and
	 * an independent advisor chain is materialized when each prototype instance
	 * is created.
	 * 
	 * Revision as of September 20, 2004 partly based on patch provided by Chris Eldredge.
	 */

	/**
	 * This suffix in a value in an interceptor list indicates to expand globals.
	 */
	public static final String GLOBAL_SUFFIX = "*";

	/**
	 * Names of Advisor and Advice beans in the factory.
	 * Default is for globals expansion only.
	 */
	private String[] interceptorNames;
	
	private boolean singleton = true;

	private AdvisorAdapterRegistry advisorAdapterRegistry = GlobalAdvisorAdapterRegistry.getInstance();

	/**
	 * Indicates whether the proxy should be frozen before creation.
	 */
	private boolean freezeProxy = false;

	/**
	 * Owning bean factory, which cannot be changed after this
	 * object is initialized.
	 */
	private BeanFactory beanFactory;

	/**
	 * Name of the target or TargetSource bean. Null if the TargetSource is not specified in
	 * the interceptorNames list.
	 */
	private String targetName;

	/** If this is a singleton, the cached singleton proxy instance */
	private Object singletonInstance;


	/**
	 * Set the names of the interfaces we're proxying. If no interface
	 * is given, a CGLIB for the actual class will be created.
	 * <p>Alternatively, use the "interfaces" property of type Class array
	 * (the bean factory will automatically convert from String to Class there).
	 * @see #setInterfaces
	 */
	public void setProxyInterfaces(String[] interfaceNames) throws ClassNotFoundException {
		Class[] interfaces = AopUtils.toInterfaceArray(interfaceNames);
		setInterfaces(interfaces);
	}

	/**
	 * Set the list of Advice/Advisor bean names. This must always be set
	 * to use this factory bean in a bean factory.
	 * <p>The referenced beans should be of type Interceptor, Advisor or Advice
	 * The last entry in the list can be the name of any bean in the factory.
	 * If it's neither an Advice nor an Advisor, a new SingletonTargetSource
	 * is added to wrap it. Such a target bean cannot be used if the target or targetSource
	 * property is set, in which case the interceptorNames array must contain
	 * only Advice/Advisor bean names.
	 * @see org.aopalliance.intercept.MethodInterceptor
	 * @see org.springframework.aop.Advisor
	 * @see org.aopalliance.aop.Advice
	 * @see org.springframework.aop.target.SingletonTargetSource
	 */
	public void setInterceptorNames(String[] interceptorNames) {
		this.interceptorNames = interceptorNames;
	}

	/**
	 * Set the value of the singleton property. Governs whether this factory
	 * should always return the same proxy instance (which implies the same target)
	 * or whether it should return a new prototype instance, which implies that
	 * the target and interceptors may be new instances also, if they are obtained
	 * from prototype bean definitions. This allows for fine control of
	 * independence/uniqueness in the object graph.
	 */
	public void setSingleton(boolean singleton) {
		this.singleton = singleton;
	}

	/**
	 * Specify the AdvisorAdapterRegistry to use.
	 * Default is the global AdvisorAdapterRegistry.
	 * @see org.springframework.aop.framework.adapter.GlobalAdvisorAdapterRegistry
	 */
	public void setAdvisorAdapterRegistry(AdvisorAdapterRegistry advisorAdapterRegistry) {
		this.advisorAdapterRegistry = advisorAdapterRegistry;
	}

	public void setFrozen(boolean frozen) {
		this.freezeProxy = frozen;
	}

	public void setBeanFactory(BeanFactory beanFactory) throws BeansException {
		this.beanFactory = beanFactory;
		createAdvisorChain();
		if (this.singleton) {
			this.targetSource = freshTargetSource();
			// Eagerly initialize the shared singleton instance.
			getSingletonInstance();
			// We must listen to superclass advice change events to recache the singleton
			// instance if necessary.
			addListener(this);
		}
	}

	/**
	 * Return a proxy. Invoked when clients obtain beans from this factory bean.
	 * Create an instance of the AOP proxy to be returned by this factory.
	 * The instance will be cached for a singleton, and create on each call to
	 * getObject() for a proxy.
	 * @return a fresh AOP proxy reflecting the current state of this factory
	 */
	public Object getObject() throws BeansException {
		return this.singleton ? getSingletonInstance() : newPrototypeInstance();
	}

	/**
	 * Return the type of the proxy. Will check the singleton instance if
	 * already created, falling back to the TargetSource's target class.
	 * @see org.springframework.aop.TargetSource#getTargetClass
	 */
	public Class getObjectType() {
		return (this.singletonInstance != null ?
		    this.singletonInstance.getClass() : getTargetSource().getTargetClass());
	}

	public boolean isSingleton() {
		return this.singleton;
	}


	private Object getSingletonInstance() {
		if (this.singletonInstance == null) {
			super.setFrozen(this.freezeProxy);
			this.singletonInstance = createAopProxy().getProxy();
		}
		return this.singletonInstance;
	}

	/**
	 * Create a new prototype instance of this class's created proxy object,
	 * backed by an independent advisedSupport configuration
	 * @return a totally independent proxy, whose advice we may manipulate in isolation
	 */
	private synchronized Object newPrototypeInstance() {
		// In the case of a prototype, we need to give the proxy
		// an independent instance of the configuration.
		// In this case, no poxy will have an instance of this object's configuration,
		// but will have an independent copy.
		if (logger.isDebugEnabled()) {
			logger.debug("Creating copy of prototype ProxyFactoryBean config: " + this);
		}
		AdvisedSupport copy = new AdvisedSupport();
		// The copy needs a fresh advisor chain, and a fresh TargetSource.
		copy.copyConfigurationFrom(this, freshTargetSource(), freshAdvisorChain());
        copy.setFrozen(this.freezeProxy);
        
		if (logger.isDebugEnabled()) {