Spring源码深度分析问题：Aop实现分别是JdkDynamicAopProxy和 CglibAopProxy

Question

在invoke方法中有如下代码：

// Get the interception chain for this method.
            List<Object> chain = this.advised.getInterceptorsAndDynamicInterceptionAdvice(method, targetClass);

上面代码也就是获取拦截器链，我的理解是这样

上面这个方法最终调用了如下实现

@SuppressWarnings("serial")
public class DefaultAdvisorChainFactory implements AdvisorChainFactory, Serializable {

    @Override
    public List<Object> getInterceptorsAndDynamicInterceptionAdvice(
            Advised config, Method method, Class<?> targetClass) {

        // This is somewhat tricky... We have to process introductions first,
        // but we need to preserve order in the ultimate list.
        List<Object> interceptorList = new ArrayList<Object>(config.getAdvisors().length);
        Class<?> actualClass = (targetClass != null ? targetClass : method.getDeclaringClass());
        boolean hasIntroductions = hasMatchingIntroductions(config, actualClass);
        AdvisorAdapterRegistry registry = GlobalAdvisorAdapterRegistry.getInstance();

        for (Advisor advisor : config.getAdvisors()) {
            if (advisor instanceof PointcutAdvisor) {
                // Add it conditionally.
                PointcutAdvisor pointcutAdvisor = (PointcutAdvisor) advisor;
                if (config.isPreFiltered() || pointcutAdvisor.getPointcut().getClassFilter().matches(actualClass)) {
                    MethodInterceptor[] interceptors = registry.getInterceptors(advisor);
                    MethodMatcher mm = pointcutAdvisor.getPointcut().getMethodMatcher();
                    if (MethodMatchers.matches(mm, method, actualClass, hasIntroductions)) {
                        if (mm.isRuntime()) {
                            // Creating a new object instance in the getInterceptors() method
                            // isn't a problem as we normally cache created chains.
                            for (MethodInterceptor interceptor : interceptors) {
                                interceptorList.add(new InterceptorAndDynamicMethodMatcher(interceptor, mm));
                            }
                        }
                        else {
                            interceptorList.addAll(Arrays.asList(interceptors));
                        }
                    }
                }
            }
            else if (advisor instanceof IntroductionAdvisor) {
                IntroductionAdvisor ia = (IntroductionAdvisor) advisor;
                if (config.isPreFiltered() || ia.getClassFilter().matches(actualClass)) {
                    Interceptor[] interceptors = registry.getInterceptors(advisor);
                    interceptorList.addAll(Arrays.asList(interceptors));
                }
            }
            else {
                Interceptor[] interceptors = registry.getInterceptors(advisor);
                interceptorList.addAll(Arrays.asList(interceptors));
            }
        }

        return interceptorList;
    }

}

我的问题： 在DefaultAdvisorChainFactory 的getInterceptorsAndDynamicInterceptionAdvice方法中 for循环内 分了三种情况
if (advisor instanceof PointcutAdvisor)

else if (advisor instanceof IntroductionAdvisor) 以及

else {

            Interceptor[] interceptors = registry.getInterceptors(advisor);
            interceptorList.addAll(Arrays.asList(interceptors));
        }
        
        
        我不理解这样区分的逻辑是什么，为什么要这样区分处理，有朋友可以 解释一下吗，非常感谢### 问题描述

问题出现的环境背景及自己尝试过哪些方法

相关代码

// 请把代码文本粘贴到下方（请勿用图片代替代码）

你期待的结果是什么？实际看到的错误信息又是什么？

Answer 1

因为Advisor这个接口有PointcutAdvisor和IntroductionAdvisor两个子接口和一个静态内部实现类PrototypePlaceholderAdvisor，所以这样判断。