dubbo-client启动报错

[yanghui8837]

Exception in thread "main" java.lang.NullPointerException
at org.spring.springboot.dubbo.CityDubboConsumerService.printCity(CityDubboConsumerService.java:20)
at org.spring.springboot.ClientApplication.main(ClientApplication.java:22)

为什么这个springboot项目 启动就会直接调用CityDubboConsumerService的方法

/**

• 城市 Dubbo 服务消费者

• Created by bysocket on 28/02/2017.
  */
  @component
  public class CityDubboConsumerService {

  @reference(version = "1.0.0")
  CityDubboService cityDubboService;

  public void printCity() {
  String cityName="温岭";
  City city = cityDubboService.findCityByName(cityName); // 这行启动就报空指针
  System.out.println(city.toString());
  }
  }