Java框架spring 学习笔记（四）：BeanPostProcessor接口

如果我们需要在Spring容器完成Bean的实例化，配置和其他的初始化前后后添加一些自己的逻辑处理。

编写InitHelloWorld.java

 package com.example.spring;

 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.config.BeanPostProcessor;

 public class InitHelloWorld implements BeanPostProcessor{
     //初始化Bean前
     @Override
     public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException {
         System.out.println("Befor Initialization :"+beanName);
         return bean;
     }

     //初始化Bean后
     @Override
     public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException {
         System.out.println("After Initialization :"+beanName);
         return bean;
     }
 }

编写Beans.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <beans xmlns="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.xsd">

     <bean id="helloWorld" class="com.example.spring.HelloWorld"
           init-method="init" destroy-method="destroy">
         <property name="message" value="Hello World"></property>
     </bean>

     <bean class="com.example.spring.InitHelloWorld"></bean>
 </beans>

编写HelloWorld.java

 package com.example.spring;

 public class HelloWorld {
     private String message;
     public void setMessage(String message){
         this.message  = message;
     }

     public void getMessage(){
         System.out.println("Your Message : " + message);
     }
     //定义初始化方法
     public void init(){
         System.out.println("Bean is going through init.");
     }
     //定义销毁方法
     public void destroy(){
         System.out.println("Bean will destroy now.");
     }
 }

运行输出

BeforeInitialization : helloWorld
Bean is going through init.
AfterInitialization : helloWorld
Your Message : Hello World!
Bean will destroy now.

可以看到初始化bean的前后分别调用了postProcessBeforeInitialization和postProcessAfterInitialization方法