Spring应用事件(Application Event)

  Spring的事件为Bean与Bean的消息通信提供的支持。当一个Bean处理完了一个任务以后,希望另一个Bean知道并能做出相应的处理,这是我们就需要让另一个Bean监听当前Bean所发送的事件。 

  Spring中使用事件的大概流程如下:

  (1)定义事件

  (2)定义事件监听器

  (3)使用容器发布事件


 

示例:

  (1)定义事件

  自定义事件需要实现ApplicationEvent接口。


package learnspring.learnspring.event;

import org.springframework.context.ApplicationEvent;

/**
* @author 肖政宇
* @date 2019-09-23 14:36
* 说明:自定义事件
*/
public class DemoEvent extends ApplicationEvent {
private static final long serialVersionUID = 1L;
private String msg;

DemoEvent(Object source, String msg) {
super(source);
this.msg = msg;
}

String getMsg() {
return msg;
}

public void setMsg(String msg) {
this.msg = msg;
}
}

 

  (2)定义事件监听器

  


package learnspring.learnspring.event;

import org.springframework.context.ApplicationListener;
import org.springframework.stereotype.Component;

/**
* @author 肖政宇
* @date 2019-09-23 14:39
* 说明:事件监听器
* 实现ApplicationListener接口,同时声明监听的事件类型
*/
@Component
public class DemoListener implements ApplicationListener<DemoEvent> {
@Override
public void onApplicationEvent(DemoEvent event) {
String msg = event.getMsg();
System.out.println("我(bean-demoListener)接收到了bean-demoPublisher发布的消息:" + msg);
}
}
 

 

  (3)使用容器发布事件

package learnspring.learnspring.event;
package learnspring.learnspring.event;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.stereotype.Component;

/**
* @author 肖政宇
* @date 2019-09-23 14:43
* 说明:事件发布者
*/
@Component
public class DemoPublisher {
private ApplicationContext applicationContext;

@Autowired
public void setApplicationContext(ApplicationContext applicationContext) {
this.applicationContext = applicationContext;
}

public void publish(String msg) {
applicationContext.publishEvent(new DemoEvent(this, msg));
}
}

测试:


package learnspring.learnspring;

import learnspring.learnspring.event.DemoPublisher;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class LearnspringApplicationTests {
DemoPublisher publisher;

@Autowired
public void setPublisher(DemoPublisher publisher) {
this.publisher = publisher;
}

@Test
public void contextLoads() {
System.out.println("事件发生!");
publisher.publish("Hello World!");
}

}
 

运行结果:

Spring应用事件(Application Event)

 

 

  

Spring应用事件(Application Event)

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