如何让sping boot@Async与Java 8协同工作

我正在尝试异步调用方法。但不知怎的它不起作用。有人能帮我解决这个问题吗?

@SpringBootApplication
@EnableAsync
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
        AsyncService asyncService = new AsyncService();
        asyncService.asyncMethod();
        asyncService.asyncMethod();
    }

}

异步服务:

@Component
public class AsyncService {

    @Async
    public void asyncMethod(){

        log.info("starting...");
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        log.info("ending...");
    }
}

最后,在日志中我期望:

1. 启动。。。
3. 结束。。。

但我得到的是:

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.1.2.RELEASE)

2019-02-13 17:52:41.548  INFO 85734 --- [           main] com.example.demo.DemoApplication         : Starting DemoApplication on mntbden00122972 with PID 85734 (/Users/h3560/demo/target/classes started by h3560 in /Users/h3560/demo)
2019-02-13 17:52:41.550  INFO 85734 --- [           main] com.example.demo.DemoApplication         : No active profile set, falling back to default profiles: default
2019-02-13 17:52:42.084  INFO 85734 --- [           main] com.example.demo.DemoApplication         : Started DemoApplication in 0.76 seconds (JVM running for 1.329)
2019-02-13 17:52:42.086  INFO 85734 --- [           main] com.example.demo.services.AsyncService   : starting...
2019-02-13 17:52:44.088  INFO 85734 --- [           main] com.example.demo.services.AsyncService   : ending...
2019-02-13 17:52:44.089  INFO 85734 --- [           main] com.example.demo.services.AsyncService   : starting...
2019-02-13 17:52:46.091  INFO 85734 --- [           main] com.example.demo.services.AsyncService   : ending...