### 前言 回顾： [Okhttp的基本用法](https://www.jianshu.com/p/8e404d9c160f) [Okhttp3源码解析(1)-OkHttpClient分析](https://www.jianshu.com/p/bf1d01b79ce7) [Okhttp3源码解析(2)-Request分析](https://www.jianshu.com/p/5a85345c8ea7) [Okhttp3源码解析(3)-Call分析(整体流程)](https://www.jianshu.com/p/4ed79472797a) [Okhttp3源码解析(4)-拦截器与设计模式](https://www.jianshu.com/p/b8817597f269) 上节讲了拦截器与设计模式，今天讲`RetryAndFollowUpInterceptor`，如果我们没有去自定义拦截器， 那`RetryAndFollowUpInterceptor`是第一个拦截器。 ### 初始化 首先先看`RetryAndFollowUpInterceptor`被添加的位置：  初始化位置： call实例化方法中： ``` private RealCall(OkHttpClient client, Request originalRequest, boolean forWebSocket) { this.client = client; this.originalRequest = originalRequest; this.forWebSocket = forWebSocket; this.retryAndFollowUpInterceptor = new RetryAndFollowUpInterceptor(client, forWebSocket); } ``` 找到了初始化的位置， 下面去`RetryAndFollowUpInterceptor`种分析！ ### RetryAndFollowUpInterceptor解析 从上节我们就知道拦截器中的**intercept()是核心！** 这里贴出代码： ``` @Override public Response intercept(Chain chain) throws IOException { Request request = chain.request(); RealInterceptorChain realChain = (RealInterceptorChain) chain; Call call = realChain.call(); EventListener eventListener = realChain.eventListener(); StreamAllocation streamAllocation = new StreamAllocation(client.connectionPool(), createAddress(request.url()), call, eventListener, callStackTrace); this.streamAllocation = streamAllocation; int followUpCount = 0; Response priorResponse = null; while (true) { if (canceled) { streamAllocation.release(); throw new IOException("Canceled"); } Response response; boolean releaseConnection = true; try { response = realChain.proceed(request, streamAllocation, null, null); releaseConnection = false; } catch (RouteException e) { // The attempt to connect via a route failed. The request will not have been sent. if (!recover(e.getLastConnectException(), streamAllocation, false, request)) { throw e.getFirstConnectException(); } releaseConnection = false; continue; } catch (IOException e) { // An attempt to communicate with a server failed. The request may have been sent. boolean requestSendStarted = !(e instanceof ConnectionShutdownException); if (!recover(e, streamAllocation, requestSendStarted, request)) throw e; releaseConnection = false; continue; } finally { // We're throwing an unchecked exception. Release any resources. if (releaseConnection) { streamAllocation.streamFailed(null); streamAllocation.release(); } } // Attach the prior response if it exists. Such responses never have a body. if (priorResponse != null) { response = response.newBuilder() .priorResponse(priorResponse.newBuilder() .body(null) .build()) .build(); } Request followUp; try { followUp = followUpRequest(response, streamAllocation.route()); } catch (IOException e) { streamAllocation.release(); throw e; } if (followUp == null) { if (!forWebSocket) { streamAllocation.release(); } return response; } closeQuietly(response.body()); if (++followUpCount > MAX_FOLLOW_UPS) { streamAllocation.release(); throw new ProtocolException("Too many follow-up requests: " + followUpCount); } if (followUp.body() instanceof UnrepeatableRequestBody) { streamAllocation.release(); throw new HttpRetryException("Cannot retry str