Spring AOP 源码探索 之深入解析实例化切面通知AspectJAdvice 生成 advisors

实例化切面通知AspectJAdvice

EnableAspectJAutoProxy

开启AOP功能可用注解形式开启：
@EnableAspectJAutoProxy
看下@EnableAspectJAutoProxy注解的作用

由上图源码可知，EnableAspectJAutoProxy注解导入了AspectJAutoProxyRegist类。

AspectJAutoProxyRegistrar类分析

分析下AspectJAutoProxyRegist类的作用。
AspectJAutoProxyRegist类继承了ImportBeanDefinitionRegistrar。

class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar

会在spring ioc 扫描类定义的过程中调用里面的registerBeanDfinitions方法。

然后通过AopConfigUtils工具类在IOC容器中注册了AnnotationAwareAspectAutoProxyCreator类

AnnotationAwareAspectAutoProxyCreator

以下是AnnotationAwareAspectAutoProxyCreator类的继承关系类图

根居上面的类图可知，AnnotationAwareAspectAutoProxyCreator的父类AbstractAutoProxyCreator实现了其中的InstantiationAwareBeanPostProcessor接口方法postProcessBeforeInstantiation

postProcessBeforeInstantiation方法会在IOC容器实例化Bean的过程中调用。
调用处：
org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory
#resolveBeforeInstantiation

postProcessBeforeInstantiation方法详细分析

此方法作用会调用org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator
#postProcessBeforeInstantiation
方法再次调用shuldSkip

org.springframework.aop.aspectj.autoproxy.AspectJAwareAdvisorAutoProxyCreator
#shouldSkip

org.springframework.aop.aspectj.annotation.annotationawareaspectjautoproxycreator
#findCandidateAdvisors

org.springframework.aop.aspectj.annotation.BeanFactoryAspectJAdvisorsBuilder
#buildAspectJAdvisors
通过

this.advisorFactory.getAdvisors(factory);

找到所有的advisor。
然后将adviosr放入advisorsCache缓存中

获取advisor的具体过程

org.springframework.aop.aspectj.annotation.ReflectiveAspectJAdvisorFactory
#getAdvisor

org.springframework.aop.aspectj.annotation.InstantiationModelAwarePointcutAdvisorImpl
#InstantiationModelAwarePointcutAdvisorImpl
InstantiationModelAwarePointcutAdvisorImpl的构造方法中的instantiateAdvice 方法进行了

org.springframework.aop.aspectj.annotation.InstantiationModelAwarePointcutAdvisorImp
l
#instantiateAdvice
继续调用aspectJAdvisorFactory.getAdvice方法

org.springframework.aop.aspectj.annotation.ReflectiveAspectJAdvisorFactory
#getAdvice
通过getAdvice实例化切面通知AspectJAdvice

下面是方法代码部分截图

由上图可知，根据不同通知类型（ @Before， @After， @AfterReturning，@AfterThrowing，@Around）会实例化不同的切面通知AspectJAdvice

调用链

resolveBeforeInstantiation->
postProcessBeforeInstantiation->
shouldSkip->
findCandidateAdvisors->
buildAspectJAdvisors->
getAdvisors->
getPointcut->new InstantiationModelAwarePointcutAdvisorImpl()->
instantiateAdvice->
getAdvice->

完整调用链图示

Idea导出的完整调用链

getAdvice:232, ReflectiveAspectJAdvisorFactory (org.springframework.aop.aspectj.annotation)

instantiateAdvice:142, InstantiationModelAwarePointcutAdvisorImpl (org.springframework.aop.aspectj.annotation)

<init>:106, InstantiationModelAwarePointcutAdvisorImpl (org.springframework.aop.aspectj.annotation)

getAdvisor:209, ReflectiveAspectJAdvisorFactory (org.springframework.aop.aspectj.annotation)

getAdvisors:136, ReflectiveAspectJAdvisorFactory (org.springframework.aop.aspectj.annotation)

buildAspectJAdvisors:109, BeanFactoryAspectJAdvisorsBuilder (org.springframework.aop.aspectj.annotation)

findCandidateAdvisors:90, AnnotationAwareAspectJAutoProxyCreator (org.springframework.aop.aspectj.annotation)

shouldSkip:103, AspectJAwareAdvisorAutoProxyCreator (org.springframework.aop.aspectj.autoproxy)

postProcessBeforeInstantiation:248, AbstractAutoProxyCreator (org.springframework.aop.framework.autoproxy)

applyBeanPostProcessorsBeforeInstantiation:1042, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)

resolveBeforeInstantiation:1016, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)

createBean:471, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)

getObject:312, AbstractBeanFactory$1 (org.springframework.beans.factory.support)

getSingleton:230, DefaultSingletonBeanRegistry (org.springframework.beans.factory.support)

doGetBean:308, AbstractBeanFactory (org.springframework.beans.factory.support)

getBean:197, AbstractBeanFactory (org.springframework.beans.factory.support)

preInstantiateSingletons:761, DefaultListableBeanFactory (org.springframework.beans.factory.support)

finishBeanFactoryInitialization:867, AbstractApplicationContext (org.springframework.context.support)

refresh:543, AbstractApplicationContext (org.springframework.context.support)

<init>:84, AnnotationConfigApplicationContext (org.springframework.context.annotation)

main:11, SilasMainClass (com.tuling)

总结

通过@EnableAspectJAutoProxy开启代理功能后，会导入AnnotationAwareAspectAutoProxyCreator类，通过调用类作为后置处理的方法postProcessBeforeInstatiation，在实例化Bean之前就会扫描出切点表达式和生成所有切面通知，并将切面通知放入advisorCache缓存，以便在后续实例化Bean生成代理对象时使用。

AOP创建代理类的过程

以下是对代理对象具体的生成源码进行分析。

Spring AOP 源码探索 之深入解析实例化Bean过程创建代理类$Proxy

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