使用Spring Boot怎么监听应用事件?很多新手对此不是很清楚,为了帮助大家解决这个难题,下面小编将为大家详细讲解,有这方面需求的人可以来学习下,希望你能有所收获。
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:
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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