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本文主要给大家介绍了关于Spring Boot应用事件监听的相关内容,分享出来供大家参考学习,下面话不多说了,来一起看看详细的介绍吧
 
1. Spring Boot特有的应用事件
 
除了Spring框架的事件,Spring Boot的SpringApplication也发送了一些自己的事件:
 
    ApplicationStartingEvent:在任何处理(除了注册listener和initializer)开始之前发送。
    ApplicationEnvironmentPreparedEvent: 在context创建之前,而用到context中的Environment已经被识别时发送。
    ApplicationContextInitializedEvent: SpringApplication正在启动,ApplicationContext已准备好且ApplicationContextInitializer已被调用但是bean的定义还没有被加载时发送。
    ApplicationPreparedEvent: 在context刷新之前,在bean的定义已经被加载之后调用。
    ApplicationStartedEvent: 在任何应用和command-line runner调用之前,而context已经被刷新时发送。
    ApplicationReadyEvent: 在任何应用和command-line runner被调用的时候发送,它意味着应用可以接受请求了。
    ApplicationFailedEvent: 在启动时有异常的时候发送。
 
有些事件是在ApplicationContext创建之前触发的,所以我们不能用常规的注册成bean的事件监听方式:
 
    注解了@EventListener注解分方法的类注册的bean;
    实现了ApplicationListener<Event>接口的类注册的bean。
 
像ApplicationStartedEvent和ApplicationReadyEvent是ApplicationContext创建之后触发的,可以用上述两种方式来监听事件。
 
2. 如何监听这些事件
 
我们可以通过下面的方式注册监听:
 
2.1. SpringApplication.addListeners(...)
 
SpringApplication application = new SpringApplication(StartEventsApplication.class);
application.addListeners(
  (ApplicationListener<ApplicationStartingEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
  (ApplicationListener<ApplicationEnvironmentPreparedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
  (ApplicationListener<ApplicationContextInitializedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
  (ApplicationListener<ApplicationPreparedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
  (ApplicationListener<ApplicationStartedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
  (ApplicationListener<ApplicationReadyEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName())
);
application.run(args);
 
2.2. SpringApplicationBuilder.listeners(...)
 
new SpringApplicationBuilder()
   .sources(StartEventsApplication.class)
   .listeners(
     (ApplicationListener<ApplicationStartingEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
     (ApplicationListener<ApplicationEnvironmentPreparedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
     (ApplicationListener<ApplicationContextInitializedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
     (ApplicationListener<ApplicationPreparedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
     (ApplicationListener<ApplicationStartedEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName()),
     (ApplicationListener<ApplicationReadyEvent>) event -> log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName())
     )
   .run(args);
 
2.3. META-INF/spring.factories
 
src/main/resources/META-INF/spring.factories:
 
org.springframework.context.ApplicationListener=top.wisely.startevents.listeners.ApplicationContextInitializedEventListener, \
            top.wisely.startevents.listeners.ApplicationEnvironmentPreparedEventListener, \
            top.wisely.startevents.listeners.ApplicationPreparedEventListener, \
            top.wisely.startevents.listeners.ApplicationReadyEventListener, \
            top.wisely.startevents.listeners.ApplicationStartedEventListener, \
            top.wisely.startevents.listeners.ApplicationStartingEventListener
 
监听器只需实现ApplicationListener<要监听的接口类型>接口,无需手动注册为bean:
 
public class ApplicationStartedEventListener implements ApplicationListener<ApplicationStartedEvent> {
 @Override
 public void onApplicationEvent(ApplicationStartedEvent event) {
  log.info("----------- 监听Spring Boot:" + event.getClass().getSimpleName());
 }
}
 

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