![SpringBoot -- 事件(Application Event) SpringBoot -- 事件(Application Event)](https://image.shishitao.com:8440/aHR0cHM6Ly9ia3FzaW1nLmlrYWZhbi5jb20vdXBsb2FkL2NoYXRncHQtcy5wbmc%2FIQ%3D%3D.png?!?w=700&webp=1)
Spring的事件为Bean与Bean之间的消息通信提供了支持,当一个Bean处理完一个任务之后,希望另外一个Bean知道并能做相应的处理,这时我们就需要让一个Bean监听当前Bean所发送的事件。
Spring的事件需要遵循如下流程:
- 自定义事件,集成ApplicationEvent。
- 定义事件监听器,实现ApplicationListener。
- 使用容器发布事件。
一、自定义事件
package com.cenobitor.appevent.event; import org.springframework.context.ApplicationEvent; public class DemoEvent extends ApplicationEvent { private static final long serialVersionUID = 1L;
private String msg; public DemoEvent(Object source,String msg) {
super(source);
this.msg = msg;
} public String getMsg() {
return msg;
} public void setMsg(String msg) {
this.msg = msg;
}
}
二、事件监听器
package com.cenobitor.appevent.listener; import com.cenobitor.appevent.event.DemoEvent;
import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;
//实现ApplicationListener接口,并指定监听的事件类型
@Component
public class DemoListener implements ApplicationListener<DemoEvent> { @Override
//使用onApplicationEvent方法对消息进行接收处理
public void onApplicationEvent(DemoEvent demoEvent) {
String msg = demoEvent.getMsg();
System.out.println("(bean-demoListener)接收到了bean-demoPublisher发布的消息:"+msg);
}
}
三、事件发布类
package com.cenobitor.appevent.publisher; import com.cenobitor.appevent.event.DemoEvent;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component; @Component
public class DemoPublisher {
@Autowired
//注入ApplicationContext用来发布事件
ApplicationContext applicationContext;
//使用ApplicationContext的publishEvent方法来发布
public void publish(String msg){
applicationContext.publishEvent(new DemoEvent(this,msg));
}
}
四、运行
package com.cenobitor.appevent; import com.cenobitor.appevent.publisher.DemoPublisher;
import org.springframework.context.annotation.AnnotationConfigApplicationContext; public class Main {
public static void main(String[] args) {
AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppeventApplication.class);
DemoPublisher demoPublisher = context.getBean(DemoPublisher.class);
demoPublisher.publish("hello application event");
context.close();
} }
结果:(bean-demoListener)接收到了bean-demoPublisher发布的消息:hello application event
注:摘抄自《JavaEE开发的颠覆者SpringBoot 实战》。