Spring 创建代理类流程跟踪

代码跟踪可以根据报错信息来反向分析

已spring3.0.6为例的报错信息分析

 

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'b1' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:527)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:456)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:293)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:290)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:192)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:585)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:895)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:425)
    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:139)
    at org.springframework.context.support.ClassPathXmlApplicationContext.(ClassPathXmlApplicationContext.java:83)
    at com.uu.T.main(T.java:9)
Caused by: org.springframework.aop.framework.AopConfigException: Cannot proxy target class because CGLIB2 is not available. Add CGLIB to the class path or specify proxy interfaces.
    at org.springframework.aop.framework.DefaultAopProxyFactory.createAopProxy(DefaultAopProxyFactory.java:67)
    at org.springframework.aop.framework.ProxyCreatorSupport.createAopProxy(ProxyCreatorSupport.java:104)
    at org.springframework.aop.framework.ProxyFactory.getProxy(ProxyFactory.java:112)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.createProxy(AbstractAutoProxyCreator.java:476)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.wrapIfNecessary(AbstractAutoProxyCreator.java:362)
    at org.springframework.aop.framework.autoproxy.AbstractAutoProxyCreator.postProcessAfterInitialization(AbstractAutoProxyCreator.java:322)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyBeanPostProcessorsAfterInitialization(AbstractAutowireCapableBeanFactory.java:407)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1426)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)

 

动态代理生成入口

动态代理生成是在spring处于对象生命周期的后期，目标对象实例化以后会逐个调用容器中定义的 BeanPostProcessor来处理对象；

其中aop的BeanPostProcessor是只要你在配置文件中引入了 类似： 这样的标签就会自动注册到容器中；

具体逻辑可以参考文章（我觉得写得不错）：

http://www.jianshu.com/p/867991f3daa0

aop jar包中

/META-INF/spring.handlers 内容：

http\://www.springframework.org/schema/aop=org.springframework.aop.config.AopNamespaceHandler

自动执行 init() 方法

public void init() {
        // In 2.0 XSD as well as in 2.1 XSD.
        registerBeanDefinitionParser("config", new ConfigBeanDefinitionParser());
        registerBeanDefinitionParser("aspectj-autoproxy", new AspectJAutoProxyBeanDefinitionParser());
        registerBeanDefinitionDecorator("scoped-proxy", new ScopedProxyBeanDefinitionDecorator());

        // Only in 2.0 XSD: moved to context namespace as of 2.1
        registerBeanDefinitionParser("spring-configured", new SpringConfiguredBeanDefinitionParser());
    }

然后会自动执行

AspectJAutoProxyBeanDefinitionParser的parse方法，parse方法会调用 registerAspectJAnnotationAutoProxyCreatorIfNecessary方法

这个方法就会向容器中注册对应的 BeanPostProcessor

BeanPostProcessor 调用链会在我的下一篇文章中提到，即 refresh() 方法的重要部分；

 

转载于:https://www.cnblogs.com/aqu415/p/7850621.html