spring源码剖析（六）AOP实现原理剖析

	public AopProxy createAopProxy(AdvisedSupport config) throws AopConfigException {
		if (config.isOptimize() || config.isProxyTargetClass() || hasNoUserSuppliedProxyInterfaces(config)) {
			Class targetClass = config.getTargetClass();
			if (targetClass == null) {
				throw new AopConfigException("TargetSource cannot determine target class: " +
						"Either an interface or a target is required for proxy creation.");
			}
			if (targetClass.isInterface()) {
				return new JdkDynamicAopProxy(config);
			}
			return CglibProxyFactory.createCglibProxy(config);
		}
		else {
			return new JdkDynamicAopProxy(config);
		}
	}

Spring JDK动态代理实现

public Object invoke(Object proxy, Method method, Object[] args) throwsThrowable {
       MethodInvocation invocation = null;
       Object oldProxy = null;
       boolean setProxyContext = false;
 
       TargetSource targetSource = this.advised.targetSource;
       Class targetClass = null;
       Object target = null;
 
       try {
           //eqauls()方法，具目标对象未实现此方法
           if (!this.equalsDefined && AopUtils.isEqualsMethod(method)){
                return (equals(args[0])? Boolean.TRUE : Boolean.FALSE);
           }
 
           //hashCode()方法，具目标对象未实现此方法
           if (!this.hashCodeDefined && AopUtils.isHashCodeMethod(method)){
                return newInteger(hashCode());
           }
 
           //Advised接口或者其父接口中定义的方法,直接反射调用,不应用通知
           if (!this.advised.opaque &&method.getDeclaringClass().isInterface()
                    &&method.getDeclaringClass().isAssignableFrom(Advised.class)) {
                // Service invocations onProxyConfig with the proxy config...
                return AopUtils.invokeJoinpointUsingReflection(this.advised,method, args);
           }
 
           Object retVal = null;
 
           if (this.advised.exposeProxy) {
                // Make invocation available ifnecessary.
                oldProxy = AopContext.setCurrentProxy(proxy);
                setProxyContext = true;
           }
 
           //获得目标对象的类
           target = targetSource.getTarget();
           if (target != null) {
                targetClass = target.getClass();
           }
 
           //获取可以应用到此方法上的Interceptor列表
           List chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method,targetClass);
 
           //如果没有可以应用到此方法的通知(Interceptor)，此直接反射调用 method.invoke(target, args)
           if (chain.isEmpty()) {
                retVal = AopUtils.invokeJoinpointUsingReflection(target,method, args);
           } else {
                //创建MethodInvocation
                invocation = newReflectiveMethodInvocation(proxy, target, method, args, targetClass, chain);
                retVal = invocation.proceed();
           }
 
           // Massage return value if necessary.
           if (retVal != null && retVal == target &&method.getReturnType().isInstance(proxy)
                    &&!RawTargetAccess.class.isAssignableFrom(method.getDeclaringClass())) {
                // Special case: it returned"this" and the return type of the method
                // is type-compatible. Notethat we can't help if the target sets
                // a reference to itself inanother returned object.
                retVal = proxy;
           }
           return retVal;
       } finally {
           if (target != null && !targetSource.isStatic()) {
                // Must have come fromTargetSource.
               targetSource.releaseTarget(target);
           }
           if (setProxyContext) {
                // Restore old proxy.
                AopContext.setCurrentProxy(oldProxy);
           }
       }
    }

public List<Object> getInterceptorsAndDynamicInterceptionAdvice(Method method, Class targetClass) {
                   MethodCacheKeycacheKey = new MethodCacheKey(method);
                   List<Object>cached = this.methodCache.get(cacheKey);
                   if(cached == null) {
                            cached= this.advisorChainFactory.getInterceptorsAndDynamicInterceptionAdvice(
                                               this,method, targetClass);
                            this.methodCache.put(cacheKey,cached);
                   }
                   returncached;
         }

/**
    * 从提供的配置实例config中获取advisor列表,遍历处理这些advisor.如果是IntroductionAdvisor,
    * 则判断此Advisor能否应用到目标类targetClass上.如果是PointcutAdvisor,则判断
    * 此Advisor能否应用到目标方法method上.将满足条件的Advisor通过AdvisorAdaptor转化成Interceptor列表返回.
    */
    publicList getInterceptorsAndDynamicInterceptionAdvice(Advised config, Methodmethod, Class targetClass) {
       // This is somewhat tricky... we have to process introductions first,
       // but we need to preserve order in the ultimate list.
       List interceptorList = new ArrayList(config.getAdvisors().length);
 
       //查看是否包含IntroductionAdvisor
       boolean hasIntroductions = hasMatchingIntroductions(config,targetClass);
 
       //这里实际上注册一系列AdvisorAdapter,用于将Advisor转化成MethodInterceptor
       AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();
 
       Advisor[] advisors = config.getAdvisors();
        for (int i = 0; i <advisors.length; i++) {
           Advisor advisor = advisors[i];
           if (advisor instanceof PointcutAdvisor) {
                // Add it conditionally.
                PointcutAdvisor pointcutAdvisor= (PointcutAdvisor) advisor;
                if(config.isPreFiltered() ||pointcutAdvisor.getPointcut().getClassFilter().matches(targetClass)) {
                    //TODO: 这个地方这两个方法的位置可以互换下
                    //将Advisor转化成Interceptor
                    MethodInterceptor[]interceptors = registry.getInterceptors(advisor);
 
                    //检查当前advisor的pointcut是否可以匹配当前方法
                    MethodMatcher mm =pointcutAdvisor.getPointcut().getMethodMatcher();
 
                    if (MethodMatchers.matches(mm,method, targetClass, hasIntroductions)) {
                        if(mm.isRuntime()) {
                            // Creating a newobject instance in the getInterceptors() method
                            // isn't a problemas we normally cache created chains.
                            for (intj = 0; j < interceptors.length; j++) {
                               interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptors[j],mm));
                            }
                        } else {
                            interceptorList.addAll(Arrays.asList(interceptors));
                        }
                    }
                }
           } else if (advisor instanceof IntroductionAdvisor){
                IntroductionAdvisor ia =(IntroductionAdvisor) advisor;
                if(config.isPreFiltered() || ia.getClassFilter().matches(targetClass)) {
                    Interceptor[] interceptors= registry.getInterceptors(advisor);
                    interceptorList.addAll(Arrays.asList(interceptors));
                }
           } else {
                Interceptor[] interceptors =registry.getInterceptors(advisor);
                interceptorList.addAll(Arrays.asList(interceptors));
           }
       }
       return interceptorList;
}

public Object proceed() throws Throwable {
       //  We start with an index of -1and increment early.
       if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size()- 1) {
           //如果Interceptor执行完了，则执行joinPoint
           return invokeJoinpoint();
       }
 
       Object interceptorOrInterceptionAdvice =
           this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
       
       //如果要动态匹配joinPoint
       if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher){
           // Evaluate dynamic method matcher here: static part will already have
           // been evaluated and found to match.
           InterceptorAndDynamicMethodMatcher dm =
                (InterceptorAndDynamicMethodMatcher)interceptorOrInterceptionAdvice;
           //动态匹配：运行时参数是否满足匹配条件
           if (dm.methodMatcher.matches(this.method, this.targetClass,this.arguments)) {
                //执行当前Intercetpor
                returndm.interceptor.invoke(this);
           }
           else {
                //动态匹配失败时,略过当前Intercetpor,调用下一个Interceptor
                return proceed();
           }
       }
       else {
           // It's an interceptor, so we just invoke it: The pointcutwill have
           // been evaluated statically before this object was constructed.
           //执行当前Intercetpor
           return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
       }
}