回顾aop如何链式调用

柔情只为你懂 2022-10-28 10:14 144阅读 0赞

## 一 概述 ##

当多个AOP叠加的时候，具体调用的时候是通过责任链模式。

## 二 责任链模式的实例图 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NhbG1fZW5jb2Rl_size_16_color_FFFFFF_t_70][]

在该模式下，Client调用Handler中的抽象方法HandleProcess()，同时存在两个实现该抽象方法的类ConcreteHandlerA和ConcreteHandlerB，同时实现类组合了该Handler类，通过successor判断来实现链式调用。

public class ReflectiveMethodInvocation implements ProxyMethodInvocation, Cloneable {	
        @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);
    		}
    	}
    }

继续研究一下，待完全理解后再来总结！

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