AopAutoConfiguration源码阅读

代码如下：

//
// Source code recreated from a .class file by IntelliJ IDEA
// (powered by FernFlower decompiler)
//package org.springframework.boot.autoconfigure.aop;import org.aspectj.weaver.Advice;
import org.springframework.aop.config.AopConfigUtils;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;@Configuration(proxyBeanMethods = false
)
@ConditionalOnProperty(prefix = "spring.aop",name = {"auto"},havingValue = "true",matchIfMissing = true
)
public class AopAutoConfiguration {public AopAutoConfiguration() {}@Configuration(proxyBeanMethods = false)@ConditionalOnMissingClass({"org.aspectj.weaver.Advice"})@ConditionalOnProperty(prefix = "spring.aop",name = {"proxy-target-class"},havingValue = "true",matchIfMissing = true)static class ClassProxyingConfiguration {ClassProxyingConfiguration(BeanFactory beanFactory) {if (beanFactory instanceof BeanDefinitionRegistry) {BeanDefinitionRegistry registry = (BeanDefinitionRegistry)beanFactory;AopConfigUtils.registerAutoProxyCreatorIfNecessary(registry);AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);}}}@Configuration(proxyBeanMethods = false)@ConditionalOnClass({Advice.class})static class AspectJAutoProxyingConfiguration {AspectJAutoProxyingConfiguration() {}@Configuration(proxyBeanMethods = false)@EnableAspectJAutoProxy(proxyTargetClass = true)@ConditionalOnProperty(prefix = "spring.aop",name = {"proxy-target-class"},havingValue = "true",matchIfMissing = true)static class CglibAutoProxyConfiguration {CglibAutoProxyConfiguration() {}}@Configuration(proxyBeanMethods = false)@EnableAspectJAutoProxy(proxyTargetClass = false)@ConditionalOnProperty(prefix = "spring.aop",name = {"proxy-target-class"},havingValue = "false",matchIfMissing = false)static class JdkDynamicAutoProxyConfiguration {JdkDynamicAutoProxyConfiguration() {}}}
}

可以看到里面类似if-else的语法判断,决定创建哪个bean。

第一个分支决定ClassProxyingConfiguration的创建（相当于if）

第二个分支决定AspectJAutoProxyingConfiguration的创建（相当于else）

由于Advice类存在，它是aop的核心类，springBoot已经整合，所以走了第二个分支，第一个分支的@ConditionalOnMissingClass({"org.aspectj.weaver.Advice"})条件不成立

上面的类存在，所以进入AspectJAutoProxyingConfiguration类，里面又有类似的条件判断

 @Configuration(proxyBeanMethods = false)@ConditionalOnClass({Advice.class})static class AspectJAutoProxyingConfiguration {AspectJAutoProxyingConfiguration() {}@Configuration(proxyBeanMethods = false)@EnableAspectJAutoProxy(proxyTargetClass = true)@ConditionalOnProperty(prefix = "spring.aop",name = {"proxy-target-class"},havingValue = "true",matchIfMissing = true)static class CglibAutoProxyConfiguration {CglibAutoProxyConfiguration() {}}@Configuration(proxyBeanMethods = false)@EnableAspectJAutoProxy(proxyTargetClass = false)@ConditionalOnProperty(prefix = "spring.aop",name = {"proxy-target-class"},havingValue = "false",matchIfMissing = false)static class JdkDynamicAutoProxyConfiguration {JdkDynamicAutoProxyConfiguration() {}}}

     对比两个配置类CglibAutoProxyConfiguration和JdkDynamicAutoProxyConfiguration上的条件。

1.CglibAutoProxyConfiguration类上的注解

    1）proxy-target-class配置值为true

    2)上面配置不存在

   当上面两个一个成立便会执行。

    3）@EnableAspectJAutoProxy( proxyTargetClass = true )注解

        启用AspectJ的自动代理功能，允许使用AspectJ风格的切面编程。设置为true时，强制使用CGLIB代理而不是JDK动态代理，确保即使目标类没有实现接口也能正常创建代理对象，默认值为false，表示优先使用JDK动态代理

    4）@Configuration( proxyBeanMethods = false )

       这个属性控制Spring是否为@Configuration类创建CGLIB代理：
proxyBeanMethods = false：不创建代理，提升性能

2.JdkDynamicAutoProxyConfiguration类上的注解

      1）proxy-target-class配置值为fasle，配置不存在则不匹配

      上面条件成立才会走这个逻辑。

      2） @EnableAspectJAutoProxy( proxyTargetClass = false )注解

       proxyTargetClass 指定代理方式，false表示使用JDK动态代理（基于接口）

       3）@Configuration( proxyBeanMethods = false )

          不创建CGLIB代理，提升性能

由于配置缺少，最后选择了创建CglibAutoProxyConfiguration类的逻辑。其中CglibAutoProxyConfiguration类上的@EnableAspectJAutoProxy注解还会继续注入bean。

点开@EnableAspectJAutoProxy注解

在进入导入类AspectJAutoProxyRegistrar里面

	/*** Register, escalate, and configure the AspectJ auto proxy creator based on the value* of the @{@link EnableAspectJAutoProxy#proxyTargetClass()} attribute on the importing* {@code @Configuration} class.* * @param importingClassMetadata 导入该配置类的元数据信息，包含注解配置信息* @param registry Bean定义注册器，用于注册和管理Bean定义*/@Overridepublic void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {// 注册AspectJ注解自动代理创建器AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);// 获取@EnableAspectJAutoProxy注解的属性配置AnnotationAttributes enableAspectJAutoProxy =AnnotationConfigUtils.attributesFor(importingClassMetadata, EnableAspectJAutoProxy.class);if (enableAspectJAutoProxy != null) {// 根据proxyTargetClass属性决定是否使用CGLIB代理if (enableAspectJAutoProxy.getBoolean("proxyTargetClass")) {AopConfigUtils.forceAutoProxyCreatorToUseClassProxying(registry);}// 根据exposeProxy属性决定是否暴露代理对象if (enableAspectJAutoProxy.getBoolean("exposeProxy")) {AopConfigUtils.forceAutoProxyCreatorToExposeProxy(registry);}}}

AopConfigUtils.registerAspectJAnnotationAutoProxyCreatorIfNecessary(registry);

这段代码决定org.springframework.aop.config.internalAutoProxyCreator类的创建。