Spring Boot 学习笔记《自定义事件》

心已赠人 2022-11-30 04:07 165阅读 0赞

### SpringBoot 2.x 自定义事件 ###

*  自定义事件类
 *  发布事件
 *  监听事件
 *   *  1. 实现 \`Interface ApplicationListener\`接口 + \`application.yml\`配置
     *  2. 方法加\`@EventListener\` + 类加\`@Component\`
     *  3. 实现 \`Interface ApplicationListener\`接口 + \`@Component 注解\`
     *  4. 实现 \`Interface ApplicationListener\` 接口 + \`ConfigurableApplicationContext\`手动注册
 *  参考资料

# 自定义事件类 #

package com.example.springbootdemo.event;
    
    import org.springframework.context.ApplicationEvent;
    
    /** * 自动义事件类 */
    public class MyEvent extends ApplicationEvent { 
        public MyEvent(Object source) { 
            super(source);
        }
    }

# 发布事件 #

任意需要的位置使用`applicationEventPublisher.publishEvent(xxxEvent);`

package com.example.springbootdemo.controller;
    
    import com.example.springbootdemo.event.MyEvent;
    import org.springframework.context.ApplicationEventPublisher;
    import org.springframework.web.bind.annotation.GetMapping;
    import org.springframework.web.bind.annotation.RestController;
    
    import javax.annotation.Resource;
    
    @RestController
    public class MyController { 
    
        @Resource
        private ApplicationEventPublisher applicationEventPublisher;
    
        @GetMapping("/")
        public String hi() { 
            applicationEventPublisher.publishEvent(new MyEvent("事件来啦~~~"));
            return "hello";
        }
    }

# 监听事件 #

<table> 
 <thead> 
  <tr> 
   <th>优先顺序</th> 
   <th>实现方法</th> 
   <th>推荐</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td>1</td> 
   <td>实现 <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationListener.html" rel="nofollow">ApplicationListener</a> 接口 + <code>application.yml</code>配置</td> 
   <td>否</td> 
  </tr> 
  <tr> 
   <td>2</td> 
   <td>方法加<a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/event/EventListener.html" rel="nofollow">@EventListener</a> + 类加<a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/stereotype/Component.html" rel="nofollow">@Component</a></td> 
   <td>是</td> 
  </tr> 
  <tr> 
   <td>3</td> 
   <td>实现 <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationListener.html" rel="nofollow">ApplicationListener</a> 接口 + 类上加<a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/stereotype/Component.html" rel="nofollow">@Component</a></td> 
   <td>是</td> 
  </tr> 
  <tr> 
   <td>4</td> 
   <td>实现 <a href="https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationListener.html" rel="nofollow">ApplicationListener</a> 接口 + <code>ConfigurableApplicationContext</code>手动注册</td> 
   <td>否</td> 
  </tr> 
 </tbody> 
</table>

## 1. 实现 `Interface ApplicationListener<E extends ApplicationEvent>`接口 + `application.yml`配置 ##

事件监听类：`MyListener1.class`

package com.example.springbootdemo.event;
    
    import org.springframework.context.ApplicationListener;
    
    /** * 监听器 1号 */
    public class MyListener1 implements ApplicationListener<MyEvent> { 
        @Override
        public void onApplicationEvent(MyEvent myEvent) { 
            System.out.println(this.getClass().getName()+ "，收到事件：" + myEvent.getSource());
        }
    }

配置文件：`application.yml`

context:
      listener:
        classes: com.example.springbootdemo.event.MyListener1

## 2. 方法加`@EventListener` \+ 类加`@Component` ##

事件监听类：`MyListener2.class`

package com.example.springbootdemo.event;
    
    import org.springframework.context.event.EventListener;
    import org.springframework.stereotype.Component;
    
    /** * 监听器 2号 */
    @Component
    public class MyListener2 { 
        @EventListener
        public void onEvent(MyEvent myEvent) { 
            System.out.println(this.getClass().getName()+ "，收到事件：" + myEvent.getSource());
        }
    }

## 3. 实现 `Interface ApplicationListener<E extends ApplicationEvent>`接口 + `@Component 注解` ##

事件监听类：`MyListener3.class`

package com.example.springbootdemo.event;
    
    import org.springframework.context.ApplicationListener;
    import org.springframework.stereotype.Component;
    
    /** * 监听器 3号 */
    @Component
    public class MyListener3 implements ApplicationListener<MyEvent> { 
        @Override
        public void onApplicationEvent(MyEvent myEvent) { 
            System.out.println(this.getClass().getName()+ "，收到事件：" + myEvent.getSource());
        }
    }

## 4. 实现 `Interface ApplicationListener<E extends ApplicationEvent>` 接口 + `ConfigurableApplicationContext`手动注册 ##

事件监听类：`MyListener4.class`

package com.example.springbootdemo.event;
    
    import org.springframework.context.ApplicationListener;
    
    /** * 监听器 4号 */
    public class MyListener4 implements ApplicationListener<MyEvent> { 
        @Override
        public void onApplicationEvent(MyEvent myEvent) { 
            System.out.println(this.getClass().getName()+ "，收到事件：" + myEvent.getSource());
        }
    }

手动注册

package com.example.springbootdemo;
    
    import com.example.springbootdemo.event.MyListener4;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    import org.springframework.context.ConfigurableApplicationContext;
    
    @SpringBootApplication
    public class SpringbootDemoApplication { 
    
        public static void main(String[] args) { 
            ConfigurableApplicationContext context = SpringApplication.run(SpringbootDemoApplication.class, args);
            context.addApplicationListener(new MyListener4()); // 注册监听器
        }
    }

# 参考资料 #

[Class ApplicationEvent][]  
[Interface ApplicationEventPublisher][]  
[@Component][Component]  
[@EventListener][EventListener]  
[Interface ApplicationListener][]  
[字母哥课堂：20年全新-Spring Boot 2.x从青铜到王者之钻石篇、filter、interceptor、listener、架构师、SpringBoot][20_-Spring Boot 2.x_filter_interceptor_listener_SpringBoot]

[Class ApplicationEvent]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationEvent.html
[Interface ApplicationEventPublisher]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationEventPublisher.html
[Component]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/stereotype/Component.html
[EventListener]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/event/EventListener.html
[Interface ApplicationListener]: https://docs.spring.io/spring-framework/docs/current/javadoc-api/org/springframework/context/ApplicationListener.html
[20_-Spring Boot 2.x_filter_interceptor_listener_SpringBoot]: https://www.bilibili.com/video/av371865945