Cookie简介

Cookie一般用于后台和客户端数据访问的有效保证，由服务端创建，客户端保存，客户端访问时将Cookie保存在请求数据header里面，服务端收到访问请求后，解析出header的库，对本次请求进行有效的验证

Android端整体流程是这样的，先获取当前请求的 Cookie , 然后进行本地持久化存储。判断当前是否拿到Cookie, 或者本地是否存有 Cookie , 添加到请求头中，完成操作

移动端网络库一般都是用Retrofit库，Retrofit是对Okhttp的一次很完美的封装，并且可以自定义Okhttp，我们这里使用的方法就是利用拦截器，拦截每一次请求与访问，解析收到的数据，拿到header里面的Cookie，在把Cookie封装到每一帧的请求里面去

方法一：

//第一步
//接收拦截器  获取Cookie
public class ReceivedCookiesInterceptor implements Interceptor {
  @Override
  public Response intercept(Interceptor.Chain chain) throws IOException {
      Response originalResponse = chain.proceed(chain.request());
      if (!originalResponse.headers("Set-Cookie").isEmpty()) {
          //解析Cookie
          for (String header : originalResponse.headers("Set-Cookie")) {
              if(header.contains("JSESSIONID")){
                  NetClient.COOKIE = header.substring(header.indexOf("JSESSIONID"), 
                 header.indexOf(";"));
              }
          }
      }
      return originalResponse;
  }
}

//第二步
//发送拦截器  添加Cookie到请求头
public class AddCookiesInterceptor implements Interceptor {
  @Override
  public Response intercept(Chain chain) throws IOException {
      final Request.Builder builder = chain.request().newBuilder();
      //添加Cookie
      if(!TextUtils.isEmpty(NetClient.COOKIE)){
          builder.addHeader("Cookie", NetClient.COOKIE);
      }
      return chain.proceed(builder.build());
  }
}


//第三步 OkHttpClient.Builder添加上面的两个拦截器
   static OkHttpClient getClient() {
      OkHttpClient.Builder okBuilder = (new OkHttpClient.Builder()).connectTimeout(5L, TimeUnit.SECONDS);
      okBuilder.addInterceptor(new AddCookiesInterceptor());
      okBuilder.addInterceptor(new ReceivedCookiesInterceptor());
      return okBuilder.build(); 
   }

//第四步 Retrofit 初始化中加入 client 配置：

  mRetrofit = new Retrofit.Builder()
                .baseUrl("https://www.wanandroid.com/")
                .client(client)
                .addConverterFactory(GsonConverterFactory.create())
                .addCallAdapterFactory(RxJavaCallAdapterFactory.create())
                .build();

方法二：

跟方法一样的,不同写法。

static OkHttpClient getClient() {
       OkHttpClient.Builder client = new OkHttpClient().newBuilder();
       client.interceptors().add(new Interceptor() {
           @NotNull
           @Override
           public Response intercept(Chain chain) throws IOException {
               // 获取 Cookie
               Response resp = chain.proceed(chain.request());
               List<String> cookies = resp.headers("Set-Cookie");
               StringBuilder cookieStr = new StringBuilder();
               if (cookies != null && cookies.size() > 0) {
                   for (int i = 0; i < cookies.size(); i++) {
                       cookieStr.append(cookies.get(i));
                   }
                   Log.d("TAG", "获取 Cookie: "+cookieStr);
                  // UserUtil.saveUserCookieId(cookieStr);
               }
               return resp;
           }
       });
       client.interceptors().add(new Interceptor() {
           @Override
           public Response intercept(Chain chain) throws IOException {
               // 设置 Cookie
             
             String cookieStr = UserUtil.getCookieId();
             if (EmptyUtil.StringNotEmpty(cookieStr)) {
                 return chain.proceed(chain.request().newBuilder().header("Cookie", cookieStr).build());
              }
               return chain.proceed(chain.request());
           }
       });
     client.connectTimeout(5L, TimeUnit.MILLISECONDS);
//        client.writeTimeout(TIMOUT, TimeUnit.MILLISECONDS);
//        client.readTimeout(TIMOUT, TimeUnit.MILLISECONDS);
       return client.build();
   }

参考文章：
https://blog.csdn.net/jackzhouyu/article/details/79500148
https://blog.csdn.net/lv_fq/article/details/77132273