原因是Ribbon集成了springboot和openfeign实现远程调用负载均衡。初始阶段没有添加以下配置。发现第一次远程调用，ribbon报错【readtimeout】。然后添加如下配置解决问题~#设置ribbon在项目启动时加载配置项，避免feign先调用[readtimeout]ribbon:eager-load:enabled:trueclients:api-service上面的配置字面意思是看，让Ribbon及时加载，那么问题来了？应用程序启动时功能区如何工作？好的，继续阅读！@ConfigurationProperties(prefix="ribbon.eager-load")publicclassRibbonEagerLoadProperties{privatebooleanenabled=false;privateListclients;}看吧，org.springframework.cloud.netflix.ribbon.RibbonEagerLoadProperties运行起来了。那么这个类是如何被调用的呢？@EnableConfigurationProperties({RibbonEagerLoadProperties.class,ServerIntrospectorProperties.class})@ConditionalOnProperty(value="spring.cloud.loadbalancer.ribbon.enabled",havingValue="true",matchIfMissing=true)公共类RibbonAutoConfiguration{@Autowired(required=false)privateListconfigurations=newArrayList<>();@Autowired私人RibbonEagerLoadPropertiesribbonEagerLoadProperties;@Bean@ConditionalOnProperty("ribbon.eager-load.enabled")publicRibbonApplicationContextInitializerribbonApplicationContextInitializer(){返回新的RibbonApplicationContextInitializer(springClientFactory(),ribbonEagerLoadProperties.getClients());}}这个类在spring-cloud-netflix包中，注入ribbonEagerLoadProperties，然后在ribbonApplicationContextInitializer()中声明RibbonApplicationContextInitializer类，继承了ApplicationListener，在实现方法onApplicationEvent()中调用initialize()，将我们配置的目标客户端（即“api-service”）加载到org.springframework.cloud.context.named.NamedContextFactory的context中下面是具体的调用链：图1publicvoidonApplicationEvent(ApplicationReadyEventevent){if(clientNames!=null){for(StringclientName:clientNames){this.springClientFactory.getContext(clientName);}}}protectedAnnotationConfigApplicationContextgetContext(Stringname){if(!this.contexts.containsKey(name)){synchronized(this.contexts){if(!this.contexts.containsKey(name)){//看这里和这里this.contexts.put（名字，createContext（名字））；}}}返回this.contexts.get(name);}下图是NamedContextFactory中存储的AnnotationConfigApplicationContext实例：图2下面我们调用了远程服务的checkToken()，下图是响应好的具体调用栈信息：图3至此，Robbin的工作方式已经大致了解一下，更多关于Robbin的细节后续会持续更新。欢迎留言交流~可以继续探索feign执行细节org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient.execute()。publicResponseexecute(Requestrequest,Request.Optionsoptions)throwsIOException{try{URIasUri=URI.create(request.url());StringclientName=asUri.getHost();URIuriWithoutHost=cleanUrl(request.url(),clientName);FeignLoadBalancer.RibbonRequestribbonRequest=newFeignLoadBalancer.RibbonRequest(this.delegate,request,uriWithoutHost);IClientConfigrequestConfig=getClientConfig(options,clientName);//这里根据clientName执行负载均衡逻辑，根据url发送n个http请求返回lbClient(clientName).executeWithLoadBalancer(ribbonRequest,requestConfig).toResponse();}catch(ClientExceptione){IOExceptionio=findIOException(e);if(io!=null){抛出io;}抛出新的RuntimeException(e);}}feign的调用链如下：其中，Client.execute()细节：publicResponseexecute(Request请求，选项options)throwsIOException{HttpURLConnectionconnection=convertAndSend(request,options);返回转换响应（连接，请求）；}publicHttpURLConnectiongetConnection(finalURLurl)throwsIOException{//也在这里^_tHpurtreturn)url.openConnection();}HttpURLConnectionconvertAndSend(Requestrequest,Optionsoptions)throwsIOException{finalURLurl=newURL(request.url());//重点在这里^-^finalHttpURLConnectionconnection=this.getConnection(url);if(connectioninstanceofHttpsURLConnection){HttpsURLConnectionsslCon=(HttpsURLConnection)连接；如果（sslContextFactory！=null）{sslCon.setSSLSocketFactory（sslContextFactory）;}if(hostnameVerifier!=null){sslCon.setHostnameVerifier(hostname}Verif}}看到了吗，最后使用jdk的HttpURLConnection执行http请求，得到执行结果：
