@Component("demoServiceComponent")
public class DemoServiceComponent implements DemoService {

    @Reference(async = true)
    private DemoService demoService;

    @Override
    public String sayHello(String name) {
        return demoService.sayHello(name);
    }
}

@Service("helloService")
public class HelloService {

    @Reference(async = false)
    private DemoService demoService;

    public String sayHello(String name) {
        return demoService.sayHello(name);
    }
}

public static void main(String[] args) {
    AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(ConsumerConfiguration.class);
    context.start();
    DemoService service = context.getBean("demoServiceComponent", DemoServiceComponent.class);
    HelloService helloService = context.getBean("helloService", HelloService.class);
    System.out.println("result : " + service.sayHello("sync"));
    System.out.println("result : " + helloService.sayHello("async"));
}