在Spring中，既可以实现 或在bean配置文件中指定   在初始化和销毁回调函数。在这篇文章中，我们将介绍如何使用 @PostConstruct 和 @PreDestroy 注解来做同样的事情。

注：@PostConstruct和@PreDestroy 标注不属于 Spring，它是在J2EE库- common-annotations.jar。

@PostConstruct 和 @PreDestroy

一个 CustomerService Bean使用 @PostConstruct 和 @PreDestroy 注释

package com.yiibai.customer.services;import javax.annotation.PostConstruct;import javax.annotation.PreDestroy;public class CustomerService{	String message;		public String getMessage() {	  return message;	}	public void setMessage(String message) {	  this.message = message;	}		@PostConstruct	public void initIt() throws Exception {	  System.out.println("Init method after properties are set : " + message);	}		@PreDestroy	public void cleanUp() throws Exception {	  System.out.println("Spring Container is destroy! Customer clean up");	}	}

默认情况下，Spring不会意识到@PostConstruct和@PreDestroy注解。要启用它，要么注册“CommonAnnotationBeanPostProcessor”，要么在bean配置文件的<context:annotation-config />‘ 指定，

1. CommonAnnotationBeanPostProcessor

2. <context:annotation-config />

执行结果

package com.yiibai.common;import org.springframework.context.ConfigurableApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;import com.yiibai.customer.services.CustomerService;public class App {    public static void main( String[] args )    {    	ConfigurableApplicationContext context =     	  new ClassPathXmlApplicationContext(new String[] {"Spring-Customer.xml"});	    	CustomerService cust = (CustomerService)context.getBean("customerService");    	    	System.out.println(cust);    	    	context.close();    }}

输出结果

Init method after properties are set : im property messagecom.yiibai.customer.services.CustomerService@47393f...INFO: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@77158a: defining beans [customerService]; root of factory hierarchySpring Container is destroy! Customer clean up

initIt()方法(@PostConstruct)被调用时，消息属性设置后 cleanUp() 方法(@PreDestroy)是在context.close()执行后被调用;

 

下载源代码 –