Spring的发布处理器（BeanPostProcessor）

来源：互联网发布：数据分析需要的技能编辑：程序博客网时间：2024/05/29 16:11

BeanFactoryPostProcessor和BeanPostProcessor都是spring初始化bean的扩展点，两个接口非常相似。

一、BeanFactoryPostProcessor可以对bean的定义（配置元数据）进行处理。也就是说，Spring IoC容器允许BeanFactoryPostProcessor在容器实际实例化任何其它的bean之前读取配置元数据，并有可能修改它。通过beanFactory可以获取bean的示例或定义等，同时可以修改bean的属性，这是和BeanPostProcessor最大的区别。

BeanDefinition bd = beanFactory.getBeanDefinition("xxBean");  MutablePropertyValues mpv =  bd.getPropertyValues();  if(pv.contains("xxName"))  {      pv.addPropertyValue("xxName", "icoder");  }

如果你愿意，你可以配置多个BeanFactoryPostProcessor。通过设置'order'属性来控制BeanFactoryPostProcessor的执行次序。

注册BeanFactoryPostProcessor的实例，需要重写void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException方法;

二、注册BeanPostProcessor的实例，需要重载

Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException方法;

和

Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException方法;

示例：

bean：

package com.yourcompany.spring;public class HelloBean{    private String message;    public void setMessage(String message){        this.message  = message;    }    public void getMessage(){        System.out.println("Your Message : " + message);    }    public void init(){        System.out.println("Bean is going through init.");    }}

processor：

package com.yourcompany.spring;import org.springframework.beans.BeansException;import org.springframework.beans.factory.config.BeanPostProcessor;public class Processor implements BeanPostProcessor{public Object postProcessAfterInitialization(Object arg0, String arg1)throws BeansException {System.out.println("After Initialization : " + arg0);return arg0;}public Object postProcessBeforeInitialization(Object arg0, String arg1)throws BeansException {System.out.println("Before Initialization : " + arg0);return arg0;}}

applicationContext.xml：

<?xml version="1.0" encoding="UTF-8"?><beansxmlns="http://www.springframework.org/schema/beans"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd">     <bean id="processor" class="com.yourcompany.spring.Processor"></bean>    <bean id="helloBean" class="com.yourcompany.spring.HelloBean" init-method="init">    <property name="message" value="Hello,World!"/>    </bean></beans>

程序主入口：

package com.yourcompany.spring;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class Hello{    public static void main(String[] args) {ApplicationContext context=new ClassPathXmlApplicationContext("applicationContext.xml");HelloBean hello=(HelloBean)context.getBean("helloBean");hello.getMessage();}}<span style="font-size:18px;"></span>

三、还有一点区别就是BeanFactoryPostProcessor的回调比BeanPostProcessor要早。

参考：http://blog.csdn.net/mn11201117/article/details/24986325

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