spring BeanPostProcessor接口
在上篇spring ApplicationListener接口(续)的例子中demo同时还实现了BeanPostProcessor接口
实现了这个接口,在spring 启动时,实现了这个接口的方法同样也会被调用,不同的是实现这个接口的类,每个bean初始化的时候都会被调用一次
先看一个这个接口的定义
/** * Factory hook that allows for custom modification of new bean instances, * e.g. checking for marker interfaces or wrapping them with proxies. * * <p>ApplicationContexts can autodetect BeanPostProcessor beans in their * bean definitions and apply them to any beans subsequently created. * Plain bean factories allow for programmatic registration of post-processors, * applying to all beans created through this factory. * * <p>Typically, post-processors that populate beans via marker interfaces * or the like will implement {@link #postProcessBeforeInitialization}, * while post-processors that wrap beans with proxies will normally * implement {@link #postProcessAfterInitialization}. * * @author Juergen Hoeller * @since 10.10.2003 * @see InstantiationAwareBeanPostProcessor * @see DestructionAwareBeanPostProcessor * @see ConfigurableBeanFactory#addBeanPostProcessor * @see BeanFactoryPostProcessor */ public interface BeanPostProcessor { /** * Apply this BeanPostProcessor to the given new bean instance <i>before</i> any bean * initialization callbacks (like InitializingBean's {@code afterPropertiesSet} * or a custom init-method). The bean will already be populated with property values. * The returned bean instance may be a wrapper around the original. * @param bean the new bean instance * @param beanName the name of the bean * @return the bean instance to use, either the original or a wrapped one; * if {@code null}, no subsequent BeanPostProcessors will be invoked * @throws org.springframework.beans.BeansException in case of errors * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet */ Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException; /** * Apply this BeanPostProcessor to the given new bean instance <i>after</i> any bean * initialization callbacks (like InitializingBean's {@code afterPropertiesSet} * or a custom init-method). The bean will already be populated with property values. * The returned bean instance may be a wrapper around the original. * <p>In case of a FactoryBean, this callback will be invoked for both the FactoryBean * instance and the objects created by the FactoryBean (as of Spring 2.0). The * post-processor can decide whether to apply to either the FactoryBean or created * objects or both through corresponding {@code bean instanceof FactoryBean} checks. * <p>This callback will also be invoked after a short-circuiting triggered by a * {@link InstantiationAwareBeanPostProcessor#postProcessBeforeInstantiation} method, * in contrast to all other BeanPostProcessor callbacks. * @param bean the new bean instance * @param beanName the name of the bean * @return the bean instance to use, either the original or a wrapped one; * if {@code null}, no subsequent BeanPostProcessors will be invoked * @throws org.springframework.beans.BeansException in case of errors * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet * @see org.springframework.beans.factory.FactoryBean */ Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException; }
这个接口就两个方法before和after,实现了这个接口则可以对方法进行包装拦截。但是最后一定要返回一个bean否则创建的bean就为空了
我就是最开始before方法直接返回空了,怎么搞控制台什么都没有
同样是上篇的例子输出如下
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
dubbo-consumer
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
com.alibaba.dubbo.config.RegistryConfig
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
org.springframework.context.event.internalEventListenerProcessor
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
org.springframework.context.event.internalEventListenerFactory
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
dubbo
++++++++++++++++++++++postProcessAfterInitialization ++++++++++++++++++++++++++
myRealBean
posted on 2018-12-20 14:40 liguangming 阅读(194) 评论(0) 编辑 收藏 举报