Spring AOP 实现流程浅析

灰太狼 2022-11-16 04:53 196阅读 0赞

### 文章目录 ###

*   *  1 AbstractAdvisorAutoProxyCreator：核心切面功能类
     *   *   *  AbstractAdvisorAutoProxyCreator
             *  AspectJAwareAdvisorAutoProxyCreator
             *  AnnotationAwareAspectJAutoProxyCreator
             *  DefaultAdvisorAutoProxyCreator
             *  InfrastructureAdvisorAutoProxyCreator
     *  2 AopAutoConfiguration：核心切面类 beanDefinition 注册
     *  3 PostProcessorRegistrationDelegate：核心切面类实例化
     *   *   *  registerBeanPostProcessors
     *  4 AbstractAutowireCapableBeanFactory：业务类代理流程
     *   *   *  initializeBean
             *  applyBeanPostProcessorsAfterInitialization

## 1 AbstractAdvisorAutoProxyCreator：核心切面功能类 ##

实现类有：

*  AnnotationAwareAspectJAutoProxyCreator（继承了 AspectJAwareAdvisorAutoProxyCreator）
 *  AspectJAwareAdvisorAutoProxyCreator
 *  DefaultAdvisorAutoProxyCreator
 *  InfrastructureAdvisorAutoProxyCreator

#### AbstractAdvisorAutoProxyCreator ####

*  aop 基础抽象类

Generic auto proxy creator that builds AOP proxies for specific beans based on detected Advisors for each bean.
    Subclasses may override the findCandidateAdvisors() method to return a custom list of Advisors applying to any object. Subclasses can also override the inherited AbstractAutoProxyCreator.shouldSkip(java.lang.Class<?>, java.lang.String) method to exclude certain objects from auto-proxying.
    Advisors or advices requiring ordering should implement the Ordered interface. This class sorts Advisors by Ordered order value. Advisors that don't implement the Ordered interface will be considered as unordered; they will appear at the end of the advisor chain in undefined order

#### AspectJAwareAdvisorAutoProxyCreator ####

重写了：sortAdvisors、extendAdvisors、shouldSkip 方法
    1、sortAdvisors：添加 aspecj 的 sort 规则
    2、extendAdvisors：在 advisor chain 的 0 位置，添加一个特殊 advisor（ExposeInvocationInterceptor 用于设置 methodInvocation TheadLocal 变量）
    3、shouldSkip：跳过 aspecj 相关类的自身代理

#### AnnotationAwareAspectJAutoProxyCreator ####

重写了：initBeanFactory、findCandidateAdvisors、isInfrastructureClass 方法
    1、initBeanFactory：添加 ReflectiveAspectJAdvisorFactory、BeanFactoryAspectJAdvisorsBuilderAdapter
    2、findCandidateAdvisors：使用 BeanFactoryAspectJAdvisorsBuilderAdapter 来解析 @Aspecj 注解的类，实例化成 Advisor 添加到 chain 中
    3、isInfrastructureClass：添加 isAspect 判断
    4、setIncludePatterns、isEligibleAspectBean：添加 includePatterns，对 @Aspecj 做过滤

#### DefaultAdvisorAutoProxyCreator ####

最普通的 AbstractAdvisorAutoProxyCreator 实现类，重写了 isEligibleAdvisorBean、setBeanName
    用于对 advisorbeanname 做 prefix 过滤

#### InfrastructureAdvisorAutoProxyCreator ####

considers infrastructure Advisor beans only,ignoring any application-defined Advisors.
    重写了：isEligibleAdvisorBean。添加：this.beanFactory.getBeanDefinition(beanName).getRole() == BeanDefinition.ROLE_INFRASTRUCTURE

## 2 AopAutoConfiguration：核心切面类 beanDefinition 注册 ##

最终 import AspectJAutoProxyRegistrar 此类，这个类就是要向 容器中注册 AnnotationAwareAspectJAutoProxyCreator beanDefinition

## 3 PostProcessorRegistrationDelegate：核心切面类实例化 ##

#### registerBeanPostProcessors ####

*  在以上方法中，会初始化所有的 BeanPostProcessors，这里就包含了 2 中的 AnnotationAwareAspectJAutoProxyCreator
 *  初始化完了之后，会将 AnnotationAwareAspectJAutoProxyCreator 实例**添加到 beanPostProcessors 中**

## 4 AbstractAutowireCapableBeanFactory：业务类代理流程 ##

#### initializeBean ####

*  在业务类实例化的时候，会调用 initializeBean 方法，然后调用其中的 applyBeanPostProcessorsAfterInitialization 方法

#### applyBeanPostProcessorsAfterInitialization ####

*  此方法会遍历所有的 beanPostProcessors（在步骤3中添加） 来对业务实例化后的类做处理
 *  其中就有 AnnotationAwareAspectJAutoProxyCreator 对业务类做 aop 的代理！