okhttp之自定义Interceptor：请求失败切换IP重试拦截器

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经过一段时间的挣扎，终于把新公司项目的网络框架换成了retrofit，由于项目是有失败重试和重定向需求的，所以需要在新的网络框架上增加这个功能，大家都知道retrofit的网络请求部分是基于okhttp的。这个时候可爱的Interceptor设计就提现出他的好处了，不需要修改其他的代码，直接增加一个拦截器就OK了

实现一个拦截器继承Interceptor（2.0到3.0之前的版本）

public class RetryAndChangeIpInterceptor implements Interceptor {String FirstIP;String SecondIP;int RetryCount;public RetryAndChangeIpInterceptor(String firsrIP, String secondIP, int tryCount) {FirstIP = firsrIP;SecondIP = secondIP;RetryCount = tryCount;}public RetryAndChangeIpInterceptor(String firsrIP, String secondIP) {FirstIP = firsrIP;SecondIP = secondIP;RetryCount = 3;}@Overridepublic Response intercept(Chain chain) throws IOException {Request request = chain.request();// try the requestResponse response = chain.proceed(request);int tryCount = 0;while (!response.isSuccessful() && tryCount <= RetryCount) {String url = request.url().toString();if (!Util.checkNULL(FirstIP) && !Util.checkNULL(SecondIP)) {//重定向if (url.contains(FirstIP)) {url = url.replace(FirstIP, SecondIP);} else if (url.contains(SecondIP)) {url = url.replace(SecondIP, FirstIP);}Request newRequest = response.request().newBuilder().url(url).build();Log.d("intercept", "Request is not successful - " + tryCount);tryCount++;// retry the requestresponse = chain.proceed(newRequest);} else {response = chain.proceed(request);}}return response;}}

3.0及以上版本（取消了httpEngine，采用了纯拦截器递归调用机制）

package com.sunshine.retrofit.interceptor;import android.util.Log;import java.io.IOException;import java.util.List;import okhttp3.Interceptor;import okhttp3.Request;import okhttp3.Response;/*** Created by 耿 on /8/12.*/public class RetryAndChangeIpInterceptor implements Interceptor {int RetryCount = 3;String FirstIP;List<String> SERVERS;public RetryAndChangeIpInterceptor(String firsrIP, List<String> sERVERS) {FirstIP = firsrIP;SERVERS = sERVERS;RetryCount = 3;}public RetryAndChangeIpInterceptor(String firsrIP, List<String> sERVERS, int tryCount) {FirstIP = firsrIP;SERVERS = sERVERS;RetryCount = tryCount;}@Overridepublic Response intercept(Chain chain) throws IOException {Request request = chain.request();// try the requestResponse response = doRequest(chain, request);int tryCount = 0;String url = request.url().toString();while (response == null && tryCount <= RetryCount) {url = switchServer(url);Request newRequest = request.newBuilder().url(url).build();Log.d("intercept", "Request is not successful - " + tryCount);tryCount++;// retry the requestresponse = doRequest(chain, newRequest);}if (response == null) {throw new IOException();}return response;}private Response doRequest(Chain chain, Request request) {Response response = null;try {response = chain.proceed(request);} catch (Exception e) {}return response;}private String switchServer(String url) {String newUrlString = url;if (url.contains(FirstIP)) {for (String server : SERVERS) {if (!FirstIP.equals(server)) {newUrlString = url.replace(FirstIP, server);break;}}} else {for (String server : SERVERS) {if (url.contains(server)) {newUrlString = url.replace(server, FirstIP);break;}}}return newUrlString;}}

配置OkHttpClient

OkHttpClient client = new OkHttpClient.Builder().addInterceptor(new RetryAndChangeIpInterceptor(BASE_URL, SecondIP))//添加失败重试及重定向拦截器.retryOnConnectionFailure(true)//允许失败重试.connectTimeout(8, TimeUnit.SECONDS).readTimeout(5, TimeUnit.SECONDS).writeTimeout(5, TimeUnit.SECONDS).build();

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