Spring 引导应用程序定期运行方法

Question

I am playing with a simple Spring Boot application and RabbitMQ.

However I cannot figure out how to run a method periodically.

Here is my Application class

@SpringBootApplication
public class SampleApp {
    @Autowired
    Sender sender;

    public static void main(String[] args) {
        SpringApplication.run(SampleApp.class, args);
    }

    @EventListener(ApplicationReadyEvent.class)
    public void doSomethingAfterStartup() {
        sender.sendMessage();
    }
}

And the sendMessage method is defined as below

@Scheduled(fixedRate = 3000L)
public void sendMessage() {
    log.info("Sending message...");
    rabbitTemplate.convertAndSend("my-exchange", "my-routing-key", "TEST MESSAGE");
}

However this method is called only once, I can see only a single line in the console.

What I missed in my code?

Thanks.

Answer 1

Looks like you are missing @EnableScheduling :

@EnableScheduling
@SpringBootApplication
public class SampleApp {
    ...
}

Quoting the documentation:

Enables Spring's scheduled task execution capability, similar to functionality found in Spring's <task:*> XML namespace. To be used on @Configuration classes as follows:

 @Configuration @EnableScheduling public class AppConfig { // various @Bean definitions }

This enables detection of @Scheduled annotations on any Spring-managed bean in the container.

Answer 2

I am usually using the Spring ThreadPoolTaskScheduler . You define it, as Bean for example then you wrap your method into a Runnable and you call it at intervals defined by a CronTrigger . The result can be retrieved using a ScheduledFuture

Check https://www.baeldung.com/spring-task-scheduler for a complete beginner tutorial.

Answer 3

Here's an alternative way if you don't want to rely on Spring's scheduler.

It's using rxjava2, here's an example:

@Component
public class MessagePublisher {

  Sender sender;
  Disposable d;

  @Autowired
  public Config(Sender sender) {
    this.sender = sender;
    this.d = doSomethingAfterStartup();
  }

  public Disposable doSomethingAfterStartup() {
    return Observable.interval(3000, TimeUnit.MILLISECONDS).subscribe(tick -> {
      sender.sendMessage();
     });
  }

}