Spring的事件(Applicaction Event)为Bean与Bean之间的消息通信提供了支持，当一个Bean处理完一个任务后，希望另外一个Bean知道并且能够做响应的处理，这是我们需要让另外一个Bean监听当前Bean所发送的事件。

Spring事件需要遵循如下的流程：

（1）自定义事件，继承ApplicationEvent

（2）定义事件监听器，实现ApplicationListener

（3）使用容器发布事件

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示例如下：

1、自定义事件

package com.lwh.highlight_spring4.ch2.event;/** * Created by luwenhu on 2017/9/20. */import org.springframework.context.ApplicationEvent;/** * Spring的事件为Bean与Bean之间的消息通信提供了支持，当Bean处理完一个任务后，希望另外一个Bean知道并且能做响应的处理 * 这时我们需要让另外一个Bean监听当前Bean所发送的事件 * 流程： * （1）自定义事件，继承ApplicationEvent * （2）定义事件监听器，实现ApplicationListener * （3）使用容器发布事件 *///(1)自定义一个事件public class DemoEvent extends ApplicationEvent {    private static final long serialVersionUID = 1L;    private String msg;    public String getMsg() {        return msg;    }    public void setMsg(String msg) {        this.msg = msg;    }    /**     * Create a new ApplicationEvent.     *     * @param source the component that published the event (never {
    @code null})     */    public DemoEvent(Object source,String msg) {        super(source);        this.msg = msg;    }}

2、事件监听器

package com.lwh.highlight_spring4.ch2.event;import org.springframework.context.ApplicationEvent;import org.springframework.context.ApplicationListener;import org.springframework.stereotype.Component;/** * Created by luwenhu on 2017/9/20. *///(2)事件监听器@Componentpublic class DemoListener implements ApplicationListener
     
      {    public void onApplicationEvent(DemoEvent event) {        String msg = event.getMsg();        System.out.println("我(bean-demoListener)接收到bean-demoPublisher发布的消息："+msg);    }}
     

3、事件发布类

package com.lwh.highlight_spring4.ch2.event;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.context.ApplicationContext;import org.springframework.stereotype.Component;/** * Created by luwenhu on 2017/9/20. *///(3)事件的发布类@Componentpublic class DemoPublisher {    @Autowired//注入Application用来发布事件    ApplicationContext applicationContext;    public void publish(String msg){        applicationContext.publishEvent(new DemoEvent(this,msg));    }}

4、配置类

package com.lwh.highlight_spring4.ch2.event;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;/** * Created by luwenhu on 2017/9/20. */@Configuration@ComponentScan("com.lwh.highlight_spring4.ch2.event")public class EventConfig {}

5、运行

package com.lwh.highlight_spring4.ch2.event;import org.springframework.context.annotation.AnnotationConfigApplicationContext;/** * Created by luwenhu on 2017/9/20. */public class Main {    public static void main(String[] args){        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(EventConfig.class);        DemoPublisher demoPublisher = context.getBean(DemoPublisher.class);        demoPublisher.publish("hello application event");        context.close();    }}

运行结果：