proxyfactorybean.java

一个关于Spring框架的示例应用程序,简单使用,可以参考.

			logger.debug("Copy has config: " + copy);
		}
		return copy.createAopProxy().getProxy();
	}

	/**
	 * Create the advisor (interceptor) chain. Aadvisors that are sourced
	 * from a BeanFactory will be refreshed each time a new prototype instance
	 * is added. Interceptors added programmatically through the factory API
	 * are unaffected by such changes.
	 */
	private void createAdvisorChain() throws AopConfigException, BeansException {
		if (this.interceptorNames == null || this.interceptorNames.length == 0) {
			return;
		}
		
		// Globals can't be last unless we specified a targetSource using the property... 
		if (this.interceptorNames[this.interceptorNames.length - 1].endsWith(GLOBAL_SUFFIX) &&
				this.targetSource == EMPTY_TARGET_SOURCE) {
			throw new AopConfigException("Target required after globals");
		}

		// materialize interceptor chain from bean names
		for (int i = 0; i < this.interceptorNames.length; i++) {
			String name = this.interceptorNames[i];
			if (logger.isDebugEnabled()) {
				logger.debug("Configuring advisor or advice '" + name + "'");
			}

			if (name.endsWith(GLOBAL_SUFFIX)) {
				if (!(this.beanFactory instanceof ListableBeanFactory)) {
					throw new AopConfigException(
					    "Can only use global advisors or interceptors with a ListableBeanFactory");
				}
				addGlobalAdvisor((ListableBeanFactory) this.beanFactory,
				    name.substring(0, name.length() - GLOBAL_SUFFIX.length()));
				continue;
			}
			else if (i == this.interceptorNames.length - 1 && this.targetSource == EMPTY_TARGET_SOURCE) {
				// The last name in the chain may be an Advisor/Advice or a target/TargetSource.
				// Unfortunately we don't know; we must look at type of the bean.
				if (!isNamedBeanAnAdvisorOrAdvice(this.interceptorNames[i])) {
					// Must be an interceptor.
					this.targetName = this.interceptorNames[i];
					if (logger.isInfoEnabled()) {
						logger.info("Bean with name '" + this.interceptorNames[i] +
								"' concluding interceptor chain is not an advisor class: " +
								"treating it as a target or TargetSource");
					}
					continue;
				}
				// If it IS an advice, or we can't tell, fall through and treat it as an advice...
			}
	
			// If we get here, we need to add a named interceptor.
			// We must check if it's a singleton or prototype.
			Object advice = null;
			if (isSingleton() || this.beanFactory.isSingleton(this.interceptorNames[i])) {
				// Add the real Advisor/Advice to the chain.
				advice = this.beanFactory.getBean(this.interceptorNames[i]);
			}
			else {
				// It's a prototype Advice or Advisor: replace with a prototype.
				// Avoid unnecessary creation of prototype bean just for advisor chain initialization.
				advice = new PrototypePlaceholderAdvisor(interceptorNames[i]);
			}
			addAdvisorOnChainCreation(advice, this.interceptorNames[i]);
		}
	}
	
	/**
	 * Look at bean factory metadata to work out whether this bean name,
	 * which concludes the interceptorNames list, is an Advisor or Advice,
	 * or may be a target.
	 * @param beanName bean name to check
	 * @return true if it's an Advisor or Advice
	 */
	private boolean isNamedBeanAnAdvisorOrAdvice(String beanName) {
		Class namedBeanClass = this.beanFactory.getType(beanName);
		if (namedBeanClass != null) {
			return Advisor.class.isAssignableFrom(namedBeanClass) ||
					Advice.class.isAssignableFrom(namedBeanClass);
		}
		// Treat it as an Advisor if we can't tell.
		return true;
	}


	/**
	 * Return an independent advisor chain.
	 * We need to do this every time a new prototype instance is returned,
	 * to return distinct instances of prototype Advisors and Advices.
	 */
	private List freshAdvisorChain() {		
		Advisor[] advisors = getAdvisors();
		List freshAdvisors = new ArrayList(advisors.length);

		for (int i = 0; i < advisors.length; i++) {
			if (advisors[i] instanceof PrototypePlaceholderAdvisor) {
				PrototypePlaceholderAdvisor pa = (PrototypePlaceholderAdvisor) advisors[i];
				if (logger.isDebugEnabled()) {
					logger.debug("Refreshing bean named '" + pa.getBeanName() + "'");
				}
				// Replace the placeholder with a fresh protoype instance resulting
				// from a getBean() lookup
				Object bean = this.beanFactory.getBean(pa.getBeanName());
				Advisor refreshedAdvisor = namedBeanToAdvisor(bean);
				freshAdvisors.add(refreshedAdvisor);
			}
			else {
				// Add the shared instance.
				freshAdvisors.add(advisors[i]);
			}
		}
		return freshAdvisors;
	}

	/**
	 * Add all global interceptors and pointcuts.
	 */
	private void addGlobalAdvisor(ListableBeanFactory beanFactory, String prefix) {
		String[] globalAdvisorNames = BeanFactoryUtils.beanNamesIncludingAncestors(beanFactory, Advisor.class);
		String[] globalInterceptorNames = BeanFactoryUtils.beanNamesIncludingAncestors(beanFactory, Interceptor.class);
		List beans = new ArrayList(globalAdvisorNames.length + globalInterceptorNames.length);
		Map names = new HashMap();
		for (int i = 0; i < globalAdvisorNames.length; i++) {
			String name = globalAdvisorNames[i];
			Object bean = beanFactory.getBean(name);
			beans.add(bean);
			names.put(bean, name);
		}
		for (int i = 0; i < globalInterceptorNames.length; i++) {
			String name = globalInterceptorNames[i];
			Object bean = beanFactory.getBean(name);
			beans.add(bean);
			names.put(bean, name);
		}
		Collections.sort(beans, new OrderComparator());
		for (Iterator it = beans.iterator(); it.hasNext();) {
			Object bean = it.next();
			String name = (String) names.get(bean);
			if (name.startsWith(prefix)) {
				addAdvisorOnChainCreation(bean, name);
			}
		}
	}

	/**
	 * Invoked when advice chain is created.
	 * <p>Add the given advice, advisor or object to the interceptor list.
	 * Because of these three possibilities, we can't type the signature
	 * more strongly.
	 * @param next advice, advisor or target object
	 * @param name bean name from which we obtained this object in our owning
	 * bean factory
	 */
	private void addAdvisorOnChainCreation(Object next, String name) {
		if (logger.isDebugEnabled()) {
			logger.debug("Adding advisor or TargetSource [" + next + "] with name [" + name + "]");
		}
		
		// We need to convert to an Advisor if necessary so that our source reference
		// matches what we find from superclass interceptors.
		Advisor advisor = namedBeanToAdvisor(next);
		
		// If it wasn't just updating the TargetSource.
		if (logger.isDebugEnabled()) {
			logger.debug("Adding advisor with name [" + name + "]");
		}			
		addAdvisor((Advisor) advisor);
	}
	
	/**
	 * Return a TargetSource to use when creating a proxy. If the target was not
	 * specified at the end of the interceptorNames list, the TargetSource will be
	 * this class' TargetSource member. Otherwise, we get the target bean and wrap
	 * it in a TargetSource if necessary.
	 */
	private TargetSource freshTargetSource() {
		if (this.targetName == null) {
			if (logger.isDebugEnabled()) {
				logger.debug("Not refreshing target: bean name not specified in interceptorNames");
			}
			return this.targetSource;
		}
		else {
			if (logger.isDebugEnabled()) {
				logger.debug("Refreshing target with name '" + this.targetName + "'");
			}
			Object target = this.beanFactory.getBean(this.targetName);
			return (target instanceof TargetSource) ? (TargetSource) target : new SingletonTargetSource(target);
		}
	}

	/**
	 * Convert the following object sourced from calling getBean() on a name in the
	 * interceptorNames array to an Advisor or TargetSource.
	 */
	private Advisor namedBeanToAdvisor(Object next) {
		try {
			return this.advisorAdapterRegistry.wrap(next);
		}
		catch (UnknownAdviceTypeException ex) {
			// We expected this to be an Advisor or Advice,
			// but it wasn't. This is a configuration error.
			throw new AopConfigException("Unknown advisor type " + next.getClass() +
					"; Can only include Advisor or Advice type beans in interceptorNames chain except for last entry," +
					"which may also be target or TargetSource", ex);
		}
	}


	/**
	 * @see org.springframework.aop.framework.AdvisedSupportListener#activated
	 */
	public void activated(AdvisedSupport advisedSupport) {
		// Nothing to do.
	}

	/**
	 * Blow away and recache singleton on an advice change.
	 * @see org.springframework.aop.framework.AdvisedSupportListener#adviceChanged
	 */
	public void adviceChanged(AdvisedSupport advisedSupport) {
		if (this.singleton) {
			logger.info("Advice has changed; recaching singleton instance");
			this.singletonInstance = null;
			getSingletonInstance();
		}
	}
	
	
	/**
	 * Used in the interceptor chain where we need to replace a bean with a prototype
	 * on creating a proxy.
	 */
	private static class PrototypePlaceholderAdvisor implements Advisor {

		private final String beanName;
		private final String message;
		
		public PrototypePlaceholderAdvisor(String beanName) {
			this.beanName = beanName;
			this.message = "Placeholder for prototype Advisor/Advice with bean name ='" + beanName + "'";
		}
		
		public String getBeanName() {
			return beanName;
		}
		
		public Advice getAdvice() {
			throw new UnsupportedOperationException("Cannot invoke methods: " + this.message);
		}
		
		public boolean isPerInstance() {
			throw new UnsupportedOperationException("Cannot invoke methods: " + this.message);
		}
		
		public String toString() {
			return this.message;
		}
	}

}