spring aop 中的AnnotationAwareAspectJAutoProxyCreator 创建过程

最新推荐文章于 2024-08-05 22:37:08 发布

yinbucheng

最新推荐文章于 2024-08-05 22:37:08 发布

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本文深入解析Spring框架中@EnableAspectJAutoProxy注解的作用机制，详细阐述了AnnotationAwareAspectJAutoProxyCreator的创建过程，以及如何通过AspectJAutoProxyRegistrar实现自动代理配置。

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spring aop 中的AnnotationAwareAspectJAutoProxyCreator 创建过程

我们在 EnableAspectJAutoProxy注解中看到如下语句

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(AspectJAutoProxyRegistrar.class)
public @interface EnableAspectJAutoProxy {
   boolean proxyTargetClass() default false;
   boolean exposeProxy() default false;
}

这里发现它这里会加载AspectJAutoProxyRegistrar类

class AspectJAutoProxyRegistrar implements ImportBeanDefinitionRegistrar {
 
   @Override
   public void registerBeanDefinitions(
         AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
      //这里就是注入AnnotionAwareAspectJAutoProxyCreator
      AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);
      AnnotationAttributes enableAspectJAutoProxy =
            AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class);
      if (enableAspectJAutoProxy != null) {
         if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) {
            AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);
         }
         if (enableAspectJAutoProxy.getBoolean("exposeProxy")) {
            AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry);
         }
      }
   }
}

再次进入源码中

public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry) {
   return registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry, null);
}

public static BeanDefinition registerAspectJAnnotationAutoProxyCreatorIfNecessary(BeanDefinitionRegistry registry, Object source) {
   //这里就是在注册AnnotationAspectJAutoProxyCreator
   return registerOrEscalateApcAsRequired(AnnotationAwareAspectJAutoProxyCreator.class, registry, source);
}

private static BeanDefinition registerOrEscalateApcAsRequired(Class<?> cls, BeanDefinitionRegistry registry, Object source) {

   if (registry.containsBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME)) {
      BeanDefinition apcDefinition = registry.getBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME);
      if (!cls.getName().equals(apcDefinition.getBeanClassName())) {
         int currentPriority = findPriorityForClass(apcDefinition.getBeanClassName());
         int requiredPriority = findPriorityForClass(cls);
         if (currentPriority < requiredPriority) {
            apcDefinition.setBeanClassName(cls.getName());
         }
      }
      return null;
   }

   RootBeanDefinition beanDefinition = new RootBeanDefinition(cls);
   beanDefinition.setSource(source);
   beanDefinition.getPropertyValues().add("order", Ordered.HIGHEST_PRECEDENCE);
   beanDefinition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
   registry.registerBeanDefinition(AUTO_PROXY_CREATOR_BEAN_NAME, beanDefinition);
   return beanDefinition;
}