springcloud系列之feign服务间远程调用

1.场景还原

    在微服务架构中，服务间调用是家常便饭；如何进行服务间远程调用呢？今天笔者就springcloud中feign远程调用给大伙讲解一番，希望能够有所帮助

2.实现方案

①加入pom依赖

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-feign</artifactId>
</dependency>

②启动类的注解配置

@SpringBootApplication
@ComponentScan("com.yivi")
@MapperScan({"com.yivi.yiviproj.microservicepayment.dao","com.yivi.yivisender.dispatchdata.dao"})
@EnableTransactionManagement
@EnableCaching
@EnableEurekaClient
@EnableCircuitBreaker
@EnableFeignClients
public class MicroServicePaymentApplication{

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

③feign远程调用接口申明

@FeignClient(name = "micro-service-dispatch",fallback = PaymentDispatchHystrixClientFallback.class)
public interface PaymentDispatchFeignClient {

    @RequestMapping(value = "/v1.0/dispatch/selectByPrimaryKey/{dispatchId}", method = RequestMethod.GET)
    YiViDispatchOrder selectByPrimaryKey(@PathVariable("dispatchId")String dispatchId);

    @RequestMapping(value = "/v1.0/dispatch/updateByPrimaryKeySelective", method = RequestMethod.POST)
    int updateByPrimaryKeySelective(@RequestBody YiViDispatchOrder record);

    @RequestMapping(value = "/v1.0/dispatch/insert", method = RequestMethod.POST)
    int insert(@RequestBody YiViDispatchOrderStatusLog record);

    @RequestMapping(value = "/v1.0/dispatch/insert/{dispatchOrderCode}", method = RequestMethod.GET)
    YiViDispatchOrder findDispatchOrderByOrderCode(@PathVariable("dispatchOrderCode")String dispatchOrderCode);

}

这里得注意，请求方式不能简写，如@GetMapping或者@PostMapping，必须以@RequestMapping(method = RequestMethod.Get)替代

④请求失败回调类

@Component
@Slf4j
public class PaymentDispatchHystrixClientFallback implements PaymentDispatchFeignClient {


  @Override
  public YiViDispatchOrder selectByPrimaryKey(String dispatchId) {
    return null;
  }

  @Override
  public int updateByPrimaryKeySelective(YiViDispatchOrder record) {
    return 0;
  }

  @Override
  public int insert(YiViDispatchOrderStatusLog record) {
    return 0;
  }

  @Override
  public YiViDispatchOrder findDispatchOrderByOrderCode(String dispatchOrderCode) {
    return null;
  }

}

feign自身支持hystrix熔断回调，防止一个服务挂掉，殃及另一个服务，俗称雪崩效应。

3.feign配置

①测试用例中你可能会遇到测试用例运行成功了却抛出如下一串错：

org.springframework.beans.factory.BeanCreationNotAllowedException: Error creating bean with name 'eurekaAutoServiceRegistration': Singleton bean creation not allowed while singletons of this factory are in destruction (Do not request a bean from a BeanFactory in a destroy method implementation!)

②添加feign配置

/**
 * @auther zx
 * @date 2018/8/11 14:26
 * @discribution 处理eurekaAutoServiceRegistration异常
 */
@Component
public class FeignBeanFactoryPostProcessor implements BeanFactoryPostProcessor {

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        if (containsBeanDefinition(beanFactory, "feignContext", "eurekaAutoServiceRegistration")) {
            BeanDefinition bd = beanFactory.getBeanDefinition("feignContext");
            bd.setDependsOn("eurekaAutoServiceRegistration");
        }
    }

    private boolean containsBeanDefinition(ConfigurableListableBeanFactory beanFactory, String... beans) {
        return Arrays.stream(beans).allMatch(b -> beanFactory.containsBeanDefinition(b));
    }
}

好了，这里笔者就不测试了；我是张星，欢迎加入博主技术交流群，群号：526601468