spring源码-aop增强-5.2

　　一、aop增强就是针对于不同的切面进行的相关增强，目的当然是更好的支持相关应用和解耦。

　　二、默认的aop增强类有AspectJMethodBeforeAdvice、AspectJMethodBeforeAdvice、AspectJAfterReturningAdvice、AspectJAfterThrowingAdvice、AspectJAroundAdvice。

　　三、这里讲2个增强AspectJMethodBeforeAdvice、AspectJMethodBeforeAdvice（为什么是两个，因为这个两个有点差异）

　　四、增强源码：

　　1）AspectJMethodBeforeAdvice

　　

　　从结构上面来说是通过MethodBeforeAdvice的before()方法进行执行的。

public void before(Method method, Object[] args, Object target) throws Throwable {
        //默认的执行方式
        this.invokeAdviceMethod(this.getJoinPointMatch(), (Object)null, (Throwable)null);
    }

    protected Object invokeAdviceMethod(JoinPointMatch jpMatch, Object returnValue, Throwable ex) throws Throwable {
        return this.invokeAdviceMethodWithGivenArgs(this.argBinding(this.getJoinPoint(), jpMatch, returnValue, ex));
    }

    protected Object invokeAdviceMethodWithGivenArgs(Object[] args) throws Throwable {
        Object[] actualArgs = args;
        if (this.aspectJAdviceMethod.getParameterTypes().length == 0) {
            actualArgs = (Object[])null;
        }

        try {
            ReflectionUtils.makeAccessible(this.aspectJAdviceMethod);
            //这里就是具体调用过程了，method.invoke(object, ...agrs)
            return this.aspectJAdviceMethod.invoke(this.aspectInstanceFactory.getAspectInstance(), actualArgs);
        } catch (IllegalArgumentException var4) {
            throw new AopInvocationException("Mismatch on arguments to advice method [" + this.aspectJAdviceMethod + "]; pointcut expression [" + this.pointcut.getPointcutExpression() + "]", var4);
        } catch (InvocationTargetException var5) {
            throw var5.getTargetException();
        }
    }

　　2）AspectJAfterAdvice

　　

　　发现什么不一样了吧，这里AspectJAfterAdvice使用的是MethodInterceptor的方法拦截方式，也就是在MethodInterceptor中的invoke()作为调用过程.

public Object invoke(MethodInvocation mi) throws Throwable {
        Object var3;
        try {
            var3 = mi.proceed();
        } finally {
            //实际调用
            this.invokeAdviceMethod(this.getJoinPointMatch(), (Object)null, (Throwable)null);
        }

        return var3;
    }

    protected Object invokeAdviceMethod(JoinPointMatch jpMatch, Object returnValue, Throwable ex) throws Throwable {
        return this.invokeAdviceMethodWithGivenArgs(this.argBinding(this.getJoinPoint(), jpMatch, returnValue, ex));
    }

    protected Object invokeAdviceMethodWithGivenArgs(Object[] args) throws Throwable {
        Object[] actualArgs = args;
        if (this.aspectJAdviceMethod.getParameterTypes().length == 0) {
            actualArgs = (Object[])null;
        }

        try {
            ReflectionUtils.makeAccessible(this.aspectJAdviceMethod);
            //执行方法的过程method.invoke(object, ...agrs)
            return this.aspectJAdviceMethod.invoke(this.aspectInstanceFactory.getAspectInstance(), actualArgs);
        } catch (IllegalArgumentException var4) {
            throw new AopInvocationException("Mismatch on arguments to advice method [" + this.aspectJAdviceMethod + "]; pointcut expression [" + this.pointcut.getPointcutExpression() + "]", var4);
        } catch (InvocationTargetException var5) {
            throw var5.getTargetException();
        }
    }

　　五、这基本就是增强器的调用过程了，但是有点需要明确。增强的东西实在动态代理加入进去的，实际调用才会执行！