Spring ApplicationListener的使用详解

介绍

Spring ApplicationListener 是Spring事件机制的一部分,与ApplicationEvent抽象类结合完成ApplicationContext的事件通知机制.

ContextRefreshedEvent事件监听

以Spring的内置事件ContextRefreshedEvent为例,当ApplicationContext被初始化或刷新时，会触发ContextRefreshedEvent事件.如下代码示例:

@Component
public class LearnListener implements ApplicationListener<ContextRefreshedEvent> {
  @Override
  public void onApplicationEvent(ContextRefreshedEvent event) {
   //获取所有的bean
   String[] definitionNames = event.getApplicationContext().getBeanDefinitionNames();
   for (String name : definitionNames) {
     //打印名称
     System.out.println("name = " + name);
   }
  }
}

自定义事件

代码

//继承ApplicationEvent 抽象类就可以自定义事件模型
public class MyEvent extends ApplicationEvent {
 
  private Long id;
  private String message;
  public MyEvent(Object source) {
    super(source);
  }

  public MyEvent(Object source, Long id, String message) {
    super(source);
    this.id = id;
    this.message = message;
  }
  //get set 方法省略
}

//实现ApplicationListener接口
  @Component
public class MyListener implements ApplicationListener<MyEvent> {
  @Override
  public void onApplicationEvent(MyEvent event) {
    System.out.println("监听到事件: "+event.getId()+"\t"+event.getMessage());
  }
}

测试

@SpringBootTest
@RunWith(SpringRunner.class)
public class ListenerTest {
  @Autowired
  private ApplicationContext applicationContext;

  @Test
  public void testListenner() {
    MyEvent myEvent = new MyEvent("myEvent", 9527L, "十二点了 该吃饭了~");
    applicationContext.publishEvent(myEvent);
   // System.out.println("发送结束");
  }
}

结果

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