Spring AOP源码分析

男娘i 2022-01-28 11:57 277阅读 0赞

# [Spring AOP源码分析][Spring AOP] #

核心类：AbstractAutoProxyCreator

![1179709-20190415231531685-994172411.png][]

继续看：

![1179709-20190415231718063-942829424.png][]

## 流程说明 ##

1）AOP标签的定义解析刘彻骨肯定是从NamespaceHandlerSupport的实现类开始解析的，这个实现类就是AopNamespaceHandler。至于为什么会是从NamespaceHandlerSupport的实现类开始解析的，这个的话我想读者可以去在回去看看Spring自定义标签的解析流程，里面说的比较详细。

2）要启用AOP，我们一般会在Spring里面配置<aop:aspectj-autoproxy/>  ，所以在配置文件中在遇到aspectj-autoproxy标签的时候我们会采用AspectJAutoProxyBeanDefinitionParser解析器

3）进入AspectJAutoProxyBeanDefinitionParser解析器后，调用AspectJAutoProxyBeanDefinitionParser已覆盖BeanDefinitionParser的parser方法，然后parser方法把请求转交给了AopNamespaceUtils的registerAspectJAnnotationAutoProxyCreatorIfNecessary去处理

4）进入AopNamespaceUtils的registerAspectJAnnotationAutoProxyCreatorIfNecessary方法后，先调用AopConfigUtils的registerAspectJAnnotationAutoProxyCreatorIfNecessary方法，里面在转发调用给registerOrEscalateApcAsRequired，注册或者升级AnnotationAwareAspectJAutoProxyCreator类。对于AOP的实现，基本是靠AnnotationAwareAspectJAutoProxyCreator去完成的，它可以根据@point注解定义的切点来代理相匹配的bean。

5）AopConfigUtils的registerAspectJAnnotationAutoProxyCreatorIfNecessary方法处理完成之后，接下来会调用useClassProxyingIfNecessary() 处理proxy-target-class以及expose-proxy属性。如果将proxy-target-class设置为true的话，那么会强制使用CGLIB代理，否则使用jdk动态代理，expose-proxy属性是为了解决有时候目标对象内部的自我调用无法实现切面增强。

6）最后的调用registerComponentIfNecessary 方法，注册组建并且通知便于监听器做进一步处理。

## 创建AOP代理 ##

上面说到AOP的核心逻辑是在AnnotationAwareAspectJAutoProxyCreator类里面实现，那么我们先来看看这个类的层次关系

## 流程说明 ##

1） spring 容器启动，每个bean的实例化之前都会先经过AbstractAutoProxyCreator类的postProcessAfterInitialization（）这个方法，然后接下来是调用wrapIfNecessary方法。

![1179709-20190415232329973-230879617.png][]

public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
            if (bean != null) {
                Object cacheKey = getCacheKey(bean.getClass(), beanName);
                if (!this.earlyProxyReferences.contains(cacheKey)) {
                    return wrapIfNecessary(bean, beanName, cacheKey);
                }
            }
            return bean;
        }

protected Object wrapIfNecessary(Object bean, String beanName, Object cacheKey) {
            if (this.targetSourcedBeans.contains(beanName)) {
                return bean;
            }
            if (this.nonAdvisedBeans.contains(cacheKey)) {
                return bean;
            }
            if (isInfrastructureClass(bean.getClass()) || shouldSkip(bean.getClass(), beanName)) {
                this.nonAdvisedBeans.add(cacheKey);
                return bean;
            }
    
            // Create proxy if we have advice.
            Object[] specificInterceptors = getAdvicesAndAdvisorsForBean(bean.getClass(), beanName, null);
            if (specificInterceptors != DO_NOT_PROXY) {
                this.advisedBeans.add(cacheKey);
                Object proxy = createProxy(bean.getClass(), beanName, specificInterceptors, new SingletonTargetSource(bean));
                this.proxyTypes.put(cacheKey, proxy.getClass());
                return proxy;
            }
    
            this.nonAdvisedBeans.add(cacheKey);
            return bean;
        }

创建代理对象
    protected Object createProxy(
                Class<?> beanClass, String beanName, Object[] specificInterceptors, TargetSource targetSource) {
    
            ProxyFactory proxyFactory = new ProxyFactory();
            // Copy our properties (proxyTargetClass etc) inherited from ProxyConfig.
            proxyFactory.copyFrom(this);
    
            if (!shouldProxyTargetClass(beanClass, beanName)) {
                // Must allow for introductions; can't just set interfaces to
                // the target's interfaces only.
                Class<?>[] targetInterfaces = ClassUtils.getAllInterfacesForClass(beanClass, this.proxyClassLoader);
                for (Class<?> targetInterface : targetInterfaces) {
                    proxyFactory.addInterface(targetInterface);
                }
            }
    
            Advisor[] advisors = buildAdvisors(beanName, specificInterceptors);
            for (Advisor advisor : advisors) {
                proxyFactory.addAdvisor(advisor);
            }
    
            proxyFactory.setTargetSource(targetSource);
            customizeProxyFactory(proxyFactory);
    
            proxyFactory.setFrozen(this.freezeProxy);
            if (advisorsPreFiltered()) {
                proxyFactory.setPreFiltered(true);
            }
    
            return proxyFactory.getProxy(this.proxyClassLoader);
        }

![1179709-20190415232430200-1179614118.png][]

posted @ 2019-04-15 23:30 [toov5][] 阅读(...) 评论(...) [编辑][Link 1] 收藏

[Spring AOP]: https://www.cnblogs.com/toov5/p/10714134.html
[1179709-20190415231531685-994172411.png]: /images/20220128/d207e4c1387b4a7c90abf72ebec72a26.png
[1179709-20190415231718063-942829424.png]: /images/20220128/9d2bf205de5a4c07bae29e3cb2beb8ee.png
[1179709-20190415232329973-230879617.png]: /images/20220128/24bc4ca833e441d28e6d958017667e51.png
[1179709-20190415232430200-1179614118.png]: /images/20220128/37dc0cdaefda46c3af90f7d7c2c6e2f5.png
[toov5]: https://www.cnblogs.com/toov5/
[Link 1]: https://i.cnblogs.com/EditPosts.aspx?postid=10714134