openfeign、nacos获取接口提供方真实IP

源码分析

client 是 LoadBalancerFeignClient
org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient#execute

public Response execute(Request request, Request.Options options) throws IOException {try {URI asUri = URI.create(request.url());String clientName = asUri.getHost();URI uriWithoutHost = cleanUrl(request.url(), clientName);// 封装 ribbon 请求组件FeignLoadBalancer.RibbonRequest ribbonRequest = new FeignLoadBalancer.RibbonRequest(this.delegate, request, uriWithoutHost);IClientConfig requestConfig = getClientConfig(options, clientName);// 这行是关键return // 获取 FeignLoadBalancerlbClient(clientName)// 负载之后请求真实的url// com.netflix.client.AbstractLoadBalancerAwareClient#executeWithLoadBalancer(....).executeWithLoadBalancer(ribbonRequest,requestConfig).toResponse();}catch (ClientException e) {....throw new RuntimeException(e);}}

com.netflix.client.AbstractLoadBalancerAwareClient#executeWithLoadBalancer

public T executeWithLoadBalancer(final S request, final IClientConfig requestConfig) throws ClientException {LoadBalancerCommand<T> command = buildLoadBalancerCommand(request, requestConfig);try {// 在com.netflix.loadbalancer.reactive.LoadBalancerCommand#submit 中会根据 负载均衡算法之后获取到真实的ip地址return command.submit(new ServerOperation<T>() {@Override// 传入的server 就是真实的ippublic Observable<T> call(Server server) {URI finalUri = reconstructURIWithServer(server, request.getUri());// 路径替换把原本 http://client-name/xxxx 地址改为 http://127.0.0.1:9090/xxxxS requestForServer = (S) request.replaceUri(finalUri);try {// 请求父类中的 execute 方法，也就是 上面 lbClient(clientName) 返回的 FeignLoadBalancerreturn Observable.just(AbstractLoadBalancerAwareClient.this.execute(requestForServer, requestConfig));} catch (Exception e) {return Observable.error(e);}}}).toBlocking().single();} catch (Exception e) {Throwable t = e.getCause();if (t instanceof ClientException) {throw (ClientException) t;} else {throw new ClientException(e);}}}

org.springframework.cloud.openfeign.ribbon.FeignLoadBalancer#execute

@Overridepublic RibbonResponse execute(RibbonRequest request, IClientConfig configOverride)throws IOException {Request.Options options;.....// 这里的 request 就是 `org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient#execute` // 封装的FeignLoadBalancer.RibbonRequest// request.client() 返回就是 feign.Client.DefaultResponse response = request.client().execute(request.toRequest(), options);return new RibbonResponse(request.getUri(), response);}

feign.Client.Default#execute

 @Overridepublic Response execute(Request request, Options options) throws IOException {HttpURLConnection connection = convertAndSend(request, options);return convertResponse(connection).toBuilder().request(request).build();}

这里的request 中 url 就是真实的url资源路径了
现在屡屡逻辑

org.springframework.cloud.openfeign.ribbon.LoadBalancerFeignClient和feign.Client.Default
都实现了 feign.Client 接口，但是 LoadBalancerFeignClient 实际上调用的还是 feign.Client.Default，无非做了自己处理（负载），有些类似于静态代理