Spring的事件为Bean与Bean之间的通信提供了支持，当我们系统中某个Spring管理的Bean处理完某件事后，希望让其他Bean收到通知并作出相应的处理，这时可以让其他Bean监听当前这个Bean所发送的事件。

要实现事件的监听，我们要做两件事：

/** * @TODO // 自定义事件，继承ApplicationEvent接口 * @Author Lensen * @Date 2018/7/22 * @Description */public class SendMsgEvent extends ApplicationEvent {    private static final long serialVersionID = 1L;    // 收件人    public String receiver;    // 收件内容    public String content;    public SendMsgEvent(Object source) {        super(source);    }    public SendMsgEvent(Object source, String receiver, String content) {        super(source);        this.receiver = receiver;        this.content = content;    }    public void output(){        System.out.println("I had been sand a msg to " + this.receiver);    }}

/** * @TODO //定义事件监听器，实现ApplicationListener * @Author Lensen * @Date 2018/7/22 * @Description */@Componentpublic class MsgListener implements ApplicationListener
    
      {    @Override    public void onApplicationEvent(SendMsgEvent sendMsgEvent) {        sendMsgEvent.output();        System.out.println(sendMsgEvent.receiver + "received msg : " + sendMsgEvent.content );    }}
    

事件发布类

@Componentpublic class Publisher {    @Autowired    ApplicationContext applicationContext;    public void publish(Object source, String receiver, String content){        applicationContext.publishEvent(new SendMsgEvent(source, receiver, content));    }}

测试消息：WebConfig.class主要是为了扫描Publisher 和Listener类。里面有两个注解@ComponenScan和@Configuration。

public static void main(String[] args) {        AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(WebConfig.class);        Publisher publisher = applicationContext.getBean(Publisher.class);        publisher.publish("Hello,World!","Mr.Lensen", "I Love U");    }

结果：

I had been sand a msg to Mr.LensenMr.Lensen received msg : I Love U