spring boot 系统启动事件监听

spring boot在启动过程中提供了一些事件的监听,这样极大的方便了开发者拓展功能;

spring boot支持的事件类型:

事件列表

关键步骤:

1、实现接口ApplicationListener来创建自己的事件监听类;如:

@Component
public class ApplicationStartedEventListener implements ApplicationListener<ApplicationStartingEvent> {

    @Override
    public void onApplicationEvent(ApplicationStartingEvent applicationStartedEvent) {
        System.out.println("application starting .....");
    }
}

2、在启动类中注册,修改此前启动类的代码为:

@SpringBootApplication
public class SpringBootDemoApplication {
    public static void main(String[] args) {
        SpringApplication springApplication = new SpringApplication(SpringBootDemoApplication.class);
        springApplication.addListeners(new ApplicationStartedEventListener());

        springApplication.run(args);
    }
}

3、运行发现启动前先打印

image.png

同样的,为了省事,直接用lamda来实现其他几个接口

@SpringBootApplication
public class SpringBootDemoApplication {

    public static void main(String[] args) {
        SpringApplication springApplication = new SpringApplication(SpringBootDemoApplication.class);
        springApplication.addListeners(new ApplicationStartedEventListener());

        springApplication.addListeners((ApplicationListener<ApplicationPreparedEvent>) event -> {
            System.out.println("application prepared event");
        });

        springApplication.addListeners((ApplicationListener<ApplicationReadyEvent>) event -> {
            System.out.println("application ready event");
        });

        springApplication.run(args);
    }
}

系统启动时,执行顺序为:application starting > application prepared > application ready