解析Java的Spring框架的BeanPostProcessor发布处理器

package com.yiibai;

public class HelloWorld {
  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.");
  }

  public void destroy(){
   System.out.println("Bean will destroy now.");
  }
}

package com.yiibai;

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

public class InitHelloWorld implements BeanPostProcessor {
 
  public Object postProcessBeforeInitialization(Object bean,
         String beanName) throws BeansException {
   System.out.println("BeforeInitialization : " + beanName);
   return bean; // you can return any other object as well
  }

  public Object postProcessAfterInitialization(Object bean,
         String beanName) throws BeansException {
   System.out.println("AfterInitialization : " + beanName);
   return bean; // you can return any other object as well
  }

}

package com.yiibai;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainApp {
  public static void main(String[] args) {

   AbstractApplicationContext context = 
             new ClassPathXmlApplicationContext("Beans.xml");

   HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
   obj.getMessage();
   context.registerShutdownHook();
  }
}

<?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-3.0.xsd">

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

  <bean class="com.yiibai.InitHelloWorld" />

</beans>

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