spring-boot学习笔记之Listener

spring－boot扩展了spring的ApplicationContextEvent，提供了四种事件

• ApplicationStartedEvent ：spring boot启动开始时执行的事件
• ApplicationEnvironmentPreparedEvent：spring boot 对应Enviroment已经准备完毕，但此时上下文context还没有创建。
• ApplicationPreparedEvent：spring boot上下文context创建完成，但此时spring中的bean是没有完全加载完成的。
• ApplicationFailedEvent：spring boot启动异常时执行事件

* 硬编码注册Listener

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(Application.class);
        application.addListeners(new ApplicationListenerEnvironmentPrepared());
        application.addListeners(new ApplicationListenerFailed());
        application.addListeners(new ApplicationListenerPrepared());
        application.addListeners(new ApplicationListenerStarted());
        application.run(args);
    }
}
public class ApplicationListenerEnvironmentPrepared implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationEnvironmentPreparedEvent event) {
        System.out.println(getClass().getSimpleName());
    }
}
public class ApplicationListenerFailed implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationFailedEvent event) {
        System.out.println(getClass().getSimpleName());
    }

}
public class ApplicationListenerPrepared implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationPreparedEvent event) {
        System.out.println(getClass().getSimpleName());
    }

}
public class ApplicationListenerStarted implements ApplicationListener {
    @Override
    public void onApplicationEvent(ApplicationStartedEvent event) {
        System.out.println(getClass().getSimpleName());
    }

}

硬编码方式注册Listener结果

* 配置文件注册Listener

context.listener.classes=org.mingyu.study.listener.ApplicationListenerStarted,org.mingyu.study.listener.ApplicationListenerEnvironmentPrepared,org.mingyu.study.listener.ApplicationListenerFailed,org.mingyu.study.listener.ApplicationListenerPrepared

配置文件注册Listener结果

如果是使用配置文件来注册的话，ApplicationStartedEvent这种事件是监听不到的，因为配置文件加载代表着spring-boot已经启动，不过其他两种事件已经足够给项目上使用了，推荐还是使用配置文件的方式来注册Listener