解决dubbo消费者注入空指针java.lang.NullPointerException的问题

java.lang.reflect.InvocationTargetException
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at com.alibaba.dubbo.config.AbstractConfig.toString(AbstractConfig.java:474)
	at java.lang.String.valueOf(String.java:2994)
	at java.lang.StringBuilder.append(StringBuilder.java:131)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.AbstractAnnotationConfigBeanBuilder.build(AbstractAnnotationConfigBeanBuilder.java:79)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.buildReferenceBean(ReferenceAnnotationBeanPostProcessor.java:385)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.access$100(ReferenceAnnotationBeanPostProcessor.java:65)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor$ReferenceFieldElement.inject(ReferenceAnnotationBeanPostProcessor.java:363)
	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
	at com.alibaba.dubbo.config.spring.beans.factory.annotation.ReferenceAnnotationBeanPostProcessor.postProcessPropertyValues(ReferenceAnnotationBeanPostProcessor.java:92)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542)
	at org.springframework.context.annotation.AnnotationConfigApplicationContext.(AnnotationConfigApplicationContext.java:84)
	at com.yyl.consumer.Consumer.main(Consumer.java:10)
Caused by: java.lang.IllegalStateException: Failed to check the status of the service com.yyl.api.DemoService. No provider available for the service com.yyl.api.DemoService from the url zookeeper://127.0.0.1:2181/com.alibaba.dubbo.registry.RegistryService?application=dubbo-consumer&default.timeout=3000&dubbo=2.6.2&interface=com.yyl.api.DemoService&methods=sayHello&pid=13407®ister.ip=10.0.104.115&revision=1.0-SNAPSHOT&side=consumer×tamp=1559712185342 to the consumer 10.0.104.115 use dubbo version 2.6.2
	at com.alibaba.dubbo.config.ReferenceConfig.createProxy(ReferenceConfig.java:422)
	at com.alibaba.dubbo.config.ReferenceConfig.init(ReferenceConfig.java:333)
	at com.alibaba.dubbo.config.ReferenceConfig.get(ReferenceConfig.java:163)
	at com.alibaba.dubbo.config.spring.ReferenceBean.getObject(ReferenceBean.java:66)
	... 25 more
[19:06:05 01:23:21]  INFO (AbstractAnnotationConfigBeanBuilder.java:79)  has been built. 
Exception in thread "main" java.lang.NullPointerException
	at com.yyl.consumer.AnnotationAction.doSayHello(AnnotationAction.java:13)
	at com.yyl.consumer.Consumer.main(Consumer.java:16)

解决办法：

在zookeepper注册中心查看注册服务，生产者没有成功注册

@Service注解  我引用spring的注解了，

import org.springframework.stereotype.Service;

应该引用

import com.alibaba.dubbo.config.annotation.Service;