spring实现listener（转）

博主说未经同意，不能转载，我这种小码农，他应该不会在乎

原创地址：http://blog.csdn.net/caihaijiang/article/details/8629725

spring 允许 Bean 在初

始化完成后以及销毁前执行特定的操作。下面是常用的三种指定特定操作的方法：

• 通过实现InitializingBean/DisposableBean 接口来定制初始化之后/销毁之前的操作方法；
• 通过<bean> 元素的 init-method/destroy-method属性指定初始化之后 /销毁之前调用的操作方法；
• 在指定方法上加上@PostConstruct或@PreDestroy注解来制定该方法是在初始化之后还是销毁之前调用。

这几种配置方式，执行顺序是怎样的呢？我们通过例子来研究下：

Java类：

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;

import org.springframework.beans.factory.DisposableBean;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class InitAndDestroySeqBean implements InitializingBean,DisposableBean {

    public InitAndDestroySeqBean(){
        System.out.println("执行InitAndDestroySeqBean: 构造方法");
    }

    @PostConstruct
    public void postConstruct() {
       System.out.println("执行InitAndDestroySeqBean: postConstruct");
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        System.out.println("执行InitAndDestroySeqBean: afterPropertiesSet");
    }

    public void initMethod() {
        System.out.println("执行InitAndDestroySeqBean: init-method");
    }

    @PreDestroy
    public void preDestroy()  {
        System.out.println("执行InitAndDestroySeqBean: preDestroy");
    }

    @Override
    public void destroy() throws Exception {
        System.out.println("执行InitAndDestroySeqBean: destroy");
    }

    public void destroyMethod() {
        System.out.println("执行InitAndDestroySeqBean: destroy-method");
    }

    public static void main(String[] args) {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("com/chj/spring/bean.xml");
        context.close();
    }
}

Spring配置文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns:context="http://www.springframework.org/schema/context"
     xsi:schemaLocation="http://www.springframework.org/schema/beans
 http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
 http://www.springframework.org/schema/context
 http://www.springframework.org/schema/context/spring-context-2.5.xsd">

   <context:annotation-config/>

   <bean id="initAndDestroySeqBean" class="com.chj.spring.InitAndDestroySeqBean" init-method="initMethod" destroy-method="destroyMethod"/>
</beans>

运行InitAndDestroySeqBean的main方法，结果如下：

2013-03-03 17:11:19,098 DEBUG support.DefaultListableBeanFactory - Creating instance of bean 'initAndDestroySeqBean'
执行InitAndDestroySeqBean: 构造方法
2013-03-03 17:11:19,114 DEBUG annotation.CommonAnnotationBeanPostProcessor - Found init method on class [com.alibaba.chj.spring.InitAndDestroySeqBean]: public void com.alibaba.chj.spring.InitAndDestroySeqBean.postConstruct()
2013-03-03 17:11:19,114 DEBUG annotation.CommonAnnotationBeanPostProcessor - Found destroy method on class [com.alibaba.chj.spring.InitAndDestroySeqBean]: public void com.alibaba.chj.spring.InitAndDestroySeqBean.preDestroy()
2013-03-03 17:11:19,129 DEBUG support.DefaultListableBeanFactory - Eagerly caching bean 'initAndDestroySeqBean' to allow for resolving potential circular references
2013-03-03 17:11:19,129 DEBUG annotation.CommonAnnotationBeanPostProcessor - Invoking init method on bean 'initAndDestroySeqBean': public void com.alibaba.chj.spring.InitAndDestroySeqBean.postConstruct()
执行InitAndDestroySeqBean: postConstruct
2013-03-03 17:11:19,129 DEBUG support.DefaultListableBeanFactory - Invoking afterPropertiesSet() on bean with name 'initAndDestroySeqBean'
执行InitAndDestroySeqBean: afterPropertiesSet
2013-03-03 17:11:19,129 DEBUG support.DefaultListableBeanFactory - Invoking init method  'initMethod' on bean with name 'initAndDestroySeqBean'
执行InitAndDestroySeqBean: init-method
2013-03-03 17:11:19,129 DEBUG support.DefaultListableBeanFactory - Finished creating instance of bean 'initAndDestroySeqBean'
2013-03-03 17:11:19,129 INFO  support.ClassPathXmlApplicationContext - Closing org.springframework.context.support.ClassPathXmlApplicationContext@56a499: display name [org.springframework.context.support.ClassPathXmlApplicationContext@56a499]; startup date [Sun Mar 03 17:11:17 CST 2013]; root of context hierarchy
2013-03-03 17:11:19,129 INFO  support.DefaultListableBeanFactory - Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1292d26: defining beans [org.springframework.context.annotation.internalCommonAnnotationProcessor,org.springframework.context.annotation.internalAutowiredAnnotationProcessor,org.springframework.context.annotation.internalRequiredAnnotationProcessor,initAndDestroySeqBean]; root of factory hierarchy
2013-03-03 17:11:19,129 DEBUG annotation.CommonAnnotationBeanPostProcessor - Invoking destroy method on bean 'initAndDestroySeqBean': public void com.alibaba.chj.spring.InitAndDestroySeqBean.preDestroy()
执行InitAndDestroySeqBean: preDestroy
2013-03-03 17:11:19,145 DEBUG support.DisposableBeanAdapter - Invoking destroy() on bean with name 'initAndDestroySeqBean'
执行InitAndDestroySeqBean: destroy
2013-03-03 17:11:19,145 DEBUG support.DisposableBeanAdapter - Invoking destroy method 'destroyMethod' on bean with name 'initAndDestroySeqBean'
执行InitAndDestroySeqBean: destroy-method

从执行结果可以看出：

Bean在实例化的过程中：Constructor > @PostConstruct >InitializingBean > init-method

Bean在销毁的过程中：@PreDestroy > DisposableBean > destroy-method