使用feign时报错java.lang.IllegalStateException: Service id not legal hostname(xx_xxx)

原因：feign不支持下划线“_”，把相应的服务名都替换为减号“-”即可。

错误代码示范：

@FeignClient(value = "tensquare_article")
public interface ArticleClient {
  /**
   * 根据ID查询文章
   *
   * @param articleId
   * @return
   */
  @RequestMapping(value = "article/{articleId}", method = RequestMethod.GET)
  Result findById(@PathVariable String articleId);

报错如下

java.lang.IllegalStateException: Service id not legal hostname (tensquare_article)
	at org.springframework.util.Assert.state(Assert.java:73) ~[spring-core-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.getName(FeignClientsRegistrar.java:103) ~[spring-cloud-openfeign-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.getName(FeignClientsRegistrar.java:278) ~[spring-cloud-openfeign-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerFeignClient(FeignClientsRegistrar.java:233) ~[spring-cloud-openfeign-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerFeignClients(FeignClientsRegistrar.java:219) ~[spring-cloud-openfeign-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.springframework.cloud.openfeign.FeignClientsRegistrar.registerBeanDefinitions(FeignClientsRegistrar.java:144) ~[spring-cloud-openfeign-core-2.1.1.RELEASE.jar:2.1.1.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.lambda$loadBeanDefinitionsFromRegistrars$1(ConfigurationClassBeanDefinitionReader.java:364) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at java.util.LinkedHashMap.forEach(LinkedHashMap.java:684) ~[na:1.8.0_101]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsFromRegistrars(ConfigurationClassBeanDefinitionReader.java:363) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitionsForConfigurationClass(ConfigurationClassBeanDefinitionReader.java:145) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassBeanDefinitionReader.loadBeanDefinitions(ConfigurationClassBeanDefinitionReader.java:117) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.processConfigBeanDefinitions(ConfigurationClassPostProcessor.java:327) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.annotation.ConfigurationClassPostProcessor.postProcessBeanDefinitionRegistry(ConfigurationClassPostProcessor.java:232) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanDefinitionRegistryPostProcessors(PostProcessorRegistrationDelegate.java:275) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.PostProcessorRegistrationDelegate.invokeBeanFactoryPostProcessors(PostProcessorRegistrationDelegate.java:95) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.invokeBeanFactoryPostProcessors(AbstractApplicationContext.java:705) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:531) ~[spring-context-5.1.6.RELEASE.jar:5.1.6.RELEASE]
	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) [spring-boot-2.1.4.RELEASE.jar:2.1.4.RELEASE]
	at com.tensquare.notice.NoticeApplication.main(NoticeApplication.java:15) [classes/:na]

Process finished with exit code 1

参考：https://github.com/spring-cloud/spring-cloud-netflix/issues/1582