spring autoproxy问题(aop:config使用注意)-优快云博客

本文深入分析了使用AOP配置时遇到的代理问题，详细解释了问题产生的原因，并提供了解决方法，包括如何正确配置AutoProxyCreator以避免误代理所有bean。

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背景

公司在做监控迁移过程中，使用了aop:config进行配置。配置例子：

<aop:config>
<aop:advisor advice-ref="rpc-interceptor" pointcut-ref="rpc-pointcut"/>
</aop:config>

定义了一些advisor列表，但在实际过程中却遇到一些莫名奇妙的问题，就是原本不应该被生成代理的对象出现了jdk,cglib代理。

分析

aop:config具体的解析类为//AopNamespaceHandler.java ，通过跟踪分析，最终会创建一个autoProxyCreator。

//==========================
public void init() {
		// In 2.0 XSD as well as in 2.1 XSD.
		registerBeanDefinitionParser("config", new ConfigBeanDefinitionParser());
		registerBeanDefinitionParser("aspectj-autoproxy", new AspectJAutoProxyBeanDefinitionParser());
		registerBeanDefinitionDecorator("scoped-proxy", new ScopedProxyBeanDefinitionDecorator());

		// Only in 2.0 XSD: moved to context namespace as of 2.1
		registerBeanDefinitionParser("spring-configured", new SpringConfiguredBeanDefinitionParser());
	}

//==========================
ConfigBeanDefinitionParser.java

public BeanDefinition parse(Element element, ParserContext parserContext) {
		CompositeComponentDefinition compositeDef =
				new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));
		parserContext.pushContainingComponent(compositeDef);

		configureAutoProxyCreator(parserContext, element);//构造auto proxy

		NodeList childNodes = element.getChildNodes();
		for (int i = 0; i < childNodes.getLength(); i++) {
			Node node = childNodes.item(i);
			if (node.getNodeType() == Node.ELEMENT_NODE) {
				String localName = node.getLocalName();
				if (POINTCUT.equals(localName)) {
					parsePointcut((Element) node, parserContext);
				}
				else if (ADVISOR.equals(localName)) {
					parseAdvisor((Element) node, parserContext);
				}
				else if (ASPECT.equals(localName)) {
					parseAspect((Element) node, parserContext);
				}
			}
		}

		parserContext.popAndRegisterContainingComponent();
		return null;
	}

private void configureAutoProxyCreator(ParserContext parserContext, Element element) {
	AopNamespaceUtils.registerAspectJAutoProxyCreatorIfNecessary(parserContext, element); //调用AopNamespaceUtils创建
	}

//==========================
AopNamespaceUtils.java

public static void registerAspectJAutoProxyCreatorIfNecessary(
			ParserContext parserContext, Element sourceElement) {

		BeanDefinition beanDefinition = AopConfigUtils.registerAspectJAutoProxyCreatorIfNecessary(
				parserContext.getRegistry(), parserContext.extractSource(sourceElement));
		useClassProxyingIfNecessary(parserContext.getRegistry(), sourceElement);
		registerComponentIfNecessary(beanDefinition, parserContext);
	}

//==========================
AopConfigUtils.java

public static BeanDefinition registerAspectJAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
		return registerOrEscalateApcAsRequired(AspectJAwareAdvisorAutoProxyCreator.class, registry, source);    //创建了AspectJAwareAdvisorAutoProxyCreator
	}

最后创建的AutoProxyCreator为： AspectJAwareAdvisorAutoProxyCreator

用过DefaultAdvisorAutoProxyCreator的应该知道：

1. 它会自动扫描当前spring容器中的Advisor，自动将当前容器中的bean进行代理

2. 至于Advisor是否会对bean生效，主要是取决于对应的pointcut的定义

3. 我们定义的MethodInterceptor,BeforeAdvice等一些Advice事件，本身不是一个完整的Advisor，所以不会被AutoProxyCreator使用。(都是在运行时被wrap成一个Advisor。具体的可以看一下ProxyFactoryBean的代码)

//===========================
//ProxyFactoryBean.java

private AdvisorAdapterRegistry advisorAdapterRegistry = GlobalAdvisorAdapterRegistry.getInstance(); //定义了wrap器

//===========================
//DefaultAdvisorAdapterRegistry.java

public DefaultAdvisorAdapterRegistry() {
		registerAdvisorAdapter(new MethodBeforeAdviceAdapter());
		registerAdvisorAdapter(new AfterReturningAdviceAdapter());
		registerAdvisorAdapter(new ThrowsAdviceAdapter());
	}


	public Advisor wrap(Object adviceObject) throws UnknownAdviceTypeException {
		if (adviceObject instanceof Advisor) {
			return (Advisor) adviceObject;
		}
		if (!(adviceObject instanceof Advice)) {
			throw new UnknownAdviceTypeException(adviceObject);
		}
		Advice advice = (Advice) adviceObject;
		if (advice instanceof MethodInterceptor) {
			// So well-known it doesn't even need an adapter.
			return new DefaultPointcutAdvisor(advice);
		}
		for (int i = 0; i < this.adapters.size(); i++) {
			// Check that it is supported.
			AdvisorAdapter adapter = (AdvisorAdapter) this.adapters.get(i);
			if (adapter.supportsAdvice(advice)) {
				return new DefaultPointcutAdvisor(advice);
			}
		}
		throw new UnknownAdviceTypeException(advice);
	}

AutoProxyCreator机制

在autoProxyCreator javadoc中有明确的定义：

因为默认在AbstractAdvisorAutoProxyCreator定义了findCandidateAdvisors的行为：　(扫描spring容器中所有的Advisor)

//===========================
//AbstractAdvisorAutoProxyCreator.java
protected List findCandidateAdvisors() {
		return this.advisorRetrievalHelper.findAdvisorBeans();
	}

//===========================
//BeanFactoryAdvisorRetrievalHelper.java
public List findAdvisorBeans() {
		// Determine list of advisor bean names, if not cached already.
		String[] advisorNames = null;
		synchronized (this) {
			advisorNames = this.cachedAdvisorBeanNames;
			if (advisorNames == null) {
				// Do not initialize FactoryBeans here: We need to leave all regular beans
				// uninitialized to let the auto-proxy creator apply to them!
				advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(this.beanFactory, Advisor.class, true, false);  //从容器中获取Advisor的定义
				this.cachedAdvisorBeanNames = advisorNames;
			}
		}
		.......
		}
		return advisors;
	}

而在DefaultAdvisorAutoProxyCreator和AspectJAwareAdvisorAutoProxyCreator，AnnotationAwareAspectJAutoProxyCreator等，都是有扫描所有Advisor的动作。

结论

结论其实很明显了

因为使用了aop:config，创建了一个AspectJAwareAdvisorAutoProxyCreator
AspectJAwareAdvisorAutoProxyCreator会扫描所有的Advisor，检查下pointCut是否匹配
我们定义的Advisor中的pointcut，spring的规范是要求：[classname] + [method]．　而我们因为先前都使用了ProxyFactoryBean，都是绑定在一个class使用，所以classname使用了通配符，所以最后的配置为: [.*] + method
正因为使用了 [.*] + method的配置，导致该Advisor定义应用到了所有bean，这也就出现了问题。