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