Spring Aop 源码 (三) (执行过程)

1.执行入口

调用了CglibAopProxy.DynamicAdvisedInterceptor.intercept() 方法

List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);
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这个方法得到一个拦截器链, 是5个增强器封装成MethodInterceptor

然后 mi.proceed() 方法触发拦截器链的方法。

	@Override
	@Nullable
	public Object proceed() throws Throwable {
		// We start with an index of -1 and increment early.
		if (this.currentInterceptorIndex == this.interceptorsAndDynamicMethodMatchers.size() - 1) {
			return invokeJoinpoint();
		}

		Object interceptorOrInterceptionAdvice =
				this.interceptorsAndDynamicMethodMatchers.get(++this.currentInterceptorIndex);
		if (interceptorOrInterceptionAdvice instanceof InterceptorAndDynamicMethodMatcher) {
			// Evaluate dynamic method matcher here: static part will already have
			// been evaluated and found to match.
			InterceptorAndDynamicMethodMatcher dm =
					(InterceptorAndDynamicMethodMatcher) interceptorOrInterceptionAdvice;
			Class<?> targetClass = (this.targetClass != null ? this.targetClass : this.method.getDeclaringClass());
			if (dm.methodMatcher.matches(this.method, targetClass, this.arguments)) {
				return dm.interceptor.invoke(this);
			}
			else {
				// Dynamic matching failed.
				// Skip this interceptor and invoke the next in the chain.
				return proceed();
			}
		}
		else {
			// It's an interceptor, so we just invoke it: The pointcut will have
			// been evaluated statically before this object was constructed.
			return ((MethodInterceptor) interceptorOrInterceptionAdvice).invoke(this);
		}
	}
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最后的一个方法进入了 invoke(this), 进入了拦截器的责任链

2.进入拦截器责任链

1. ReflectiveMethodInvocation.proceed() ->
2. ExposeInvocationInterceptor.invoke(mi) -> currentInterceptorIndex = 1
3. MethodBeforeAdviceInterceptor.invoke(this) -> advice.before -> mi.proceed -> currentInterceptorIndex = 2
4. AspectJAfterAdvice.invoke(this) -> return mi.proceed() -> finally invokeAdviceMethod -> currentInterceptorIndex = 3
5. AfterReturningAdviceInterceptor.invoke(this) -> Object retVal = mi.proceed() -> this.advice.afterReturning(retVal) -> return retVal -> currentInterceptorIndex =4
6. AspectJAfterThrowingAdvice.invoke(this) -> return mi.proceed() -> catch invokeAdviceMethod
7. invokeJoinPoint() 执行连接点, 执行目标方法

ExposeInvocationInterceptor, MethodBeforeAdviceInterceptor, AspectJAfterAdvice, AfterReturningAdviceInterceptor, AspectJAfterThrowingAdvice为Filter类

CglibMethodInvocation 为 FilterChain

2.1 ExposeInvocationInterceptor

这个拦截器为暴露共享数据

ExposeInvocationInterceptor.invoke()

先是 invocation.set(mi); 这里的invocation是一个threadLocal, 可以保存共享数据

又进入了ReflectiveMethodInvocation.proceed()

2.2 MethodBeforeAdviceInterceptor

前置通知拦截器

MethodBeforeAdviceInterceptor.invoke()

先是执行了前置通知, 然后返回mi.procced()

2.3 AspectJAfterAdvice

后置通知拦截器

AspectJAfterAdvice.invoke()

返回的是 mi.proceed(), 并进行 invokeAdviceMethod()

2.4 AfterReturningAdviceInterceptor

返回通知拦截器

AfterReturningAdviceInterceptor.invoke()

2.5 AspectJAfterThrowingAdvice

异常通知

AspectJAfterThrowingAdvice.invoke()

2.6 invokeJoinPoint()

执行连接点, 用于执行方法

3.执行顺序

前置通知 => 目标方法 => 返回通知 => 后置通知

前置通知 => 目标方法 => 异常通知 => 后置通知

try{
	前置通知
	目标方法
	返回通知
}catch(){
	异常通知
}finally{
	后置通知
}
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