How to start a listening thread to perform tasks in springboot

springboot starts a listening thread to perform tasks

public class StartApplicationListener implements ApplicationListener<ContextRefreshedEvent> {

    @Override
    public void onApplicationEvent(ContextRefreshedEvent contextRefreshedEvent) {
        ApplicationContext applicationContext = contextRefreshedEvent.getApplicationContext();
        ApplicationContext parent = applicationContext.getParent();
        if (parent == null) {
            CacheManager cacheManager = applicationContext.getBean(CacheManager.class);
            Cache cache = cacheManager.getCache(MsConstants.NODE_CACHE_NAME);
           new Thread(new Runnable() {
               @Override
               public void run() {
                  //代码
                 
               }
           }).start();
        }
    }

public static void main(String[] args) {
    SpringApplication app = new SpringApplication(FigureServerApplication.class);
    app.addListeners(new StartApplicationListener());
    app.run(args);
}

Creation process of listening events in springboot

In the Spring Boot project, you can Use the annotation @Async to implement asynchronous processing, and event listening has two methods: synchronous and asynchronous.

General steps of events

• 1: Define an event.

• 2: Create a listener.

• 3: Make sure the listener is inside the container.

• 4: Publish the event for testing.

Without further ado, let’s briefly describe the demos of several different methods.

First, we create a springboot project.

First type

1: Define an event and need to inherit ApplicationEvent

public class MyEvent extends ApplicationEvent {
    public MyEvent(Object source) {
        super(source);
        System.out.println("我是一个事件，目前在事件的构造器内");
    }
}

2: Create a listener. Directly implement the ApplicationListener interface and rewrite the onApplicationEvent method.

public class MyEventListener implements ApplicationListener<MyEvent> {
    @Override
    public void onApplicationEvent(MyEvent event) {
        System.out.println("现在开始执行监听器中的内容,我是直接实现ApplicationListener接口的方式进行的");
        System.out.println("event.getSource() = " + event.getSource());
    }
}

3: Manually add the listener to the application container and publish the event.

@SpringBootApplication
public class EventTestApplication {
    public static void main(String[] args) {
//        SpringApplication.run(EventTestApplication.class, args);
        //第一种：自己手动将监听器添加到application中
        SpringApplication application = new SpringApplication(EventTestApplication.class);
        //添加监听器
        application.addListeners(new MyEventListener());
        ConfigurableApplicationContext context = application.run(args);
        //进行发布事件
        context.publishEvent(new MyEvent("Event数据源"));
        context.close();
    }
}

4: Start the main startup class and perform printing tests.

Second type

1: Same as the first type 1

2: Create a listener.

/**
 *第二种：打上Compoent注解，  将事件监听器自动加入到应用容器中
 * 这种方式不需要手动加入到容器中。
 * */
@Component
public class MyEventListener2 implements ApplicationListener<MyEvent> {
    @Override
    public void onApplicationEvent(MyEvent event) {
        System.out.println("现在开始执行监听器中的内容,我是打Compoent注解的方式进行的");
        System.out.println("event.getSource() = " + event.getSource());
    }
}

3: Publish the event and then perform startup class testing.

@SpringBootApplication
public class EventTestApplication {
    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(EventTestApplication.class, args);
        //发布事件
        context.publishEvent(new MyEvent("source"));
        context.close();
    }
}

The third type

all use annotations

1: Same as the first type 1

2: Create A listener.

/**
 *第三种:采用@EventListener注解的方式，不需要在类上实现ApplicationListener接口。
 * 直接采用的是通过注解，将方法标识为一个监听器。
 * */
@Component
public class MyEventListener3 {
    @Async//异步注解。开启一个新线程。 去掉此注解则会变成同步监听。
    @EventListener(classes = MyEvent.class)
    public void TestListener(MyEvent myEvent){
        System.out.println("我是@EventListener注解的方式实现的监听器");
        System.out.println("myEvent.getSource() = " + myEvent.getSource());
    }
}

3: Publish the event and then perform startup class testing.

@SpringBootApplication
public class EventTestApplication {
    public static void main(String[] args) {
        ConfigurableApplicationContext context = SpringApplication.run(EventTestApplication.class, args);
        //发布事件
        context.publishEvent(new MyEvent("source"));
        context.close();
    }
}

The following is the structure diagram of the code:

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