public class TokenInterceptor implements Interceptor {

  @Override
  public Response intercept(Chain chain) throws IOException {

    Request.Builder request = chain.request().newBuilder();
    //添加默认的Token请求头
    request.addHeader("Cookie", UserInfo.getInstance().getPhpSessionId());

    Response proceed = chain.proceed(request.build());
    okhttp3.MediaType mediaType = proceed.body().contentType();

    //如果token过期 再去重新请求token 然后设置token的请求头 重新发起请求 用户无感
    String content = proceed.body().string();
    if (isTokenExpired(content)) {

      String newToken = getNewToken();

      UserInfo.getInstance().setPhpSessionId(newToken);
      //使用新的Token，创建新的请求
      Request newRequest = chain.request().newBuilder()
          .addHeader("Cookie", newToken)
          .build();
      return chain.proceed(newRequest);
    }
    return proceed.newBuilder()
        .body(okhttp3.ResponseBody.create(mediaType, content))
        .build();

  }

  private String getNewToken() {
    // 通过一个特定的接口获取新的token，此处要用到同步的retrofit请求
    IndexService service = IndexService.Builder.getServer();
    Call> call = service.getToke(
        UserInfo.getInstance().getPhone(),
        UserInfo.getInstance().getPwd(),
        0);

    //要用retrofit的同步方式
    BaseObjResult newToken = null;
    try {
      newToken = call.execute().body();
    } catch (IOException e) {
      e.printStackTrace();
    }

    return newToken.getResult().getPHPSESSID();
  }

  /**
   * 根据Response，判断Token是否失效
   *
   * @return
   */
  private boolean isTokenExpired(String resultStr) {
    RequestCode requestCode = new Gson().fromJson(resultStr, RequestCode.class);
    //err==3 token过期
    if (requestCode.getErr() == 3) {
      LogUtils.e("Token登录过期了");
      ToastUtils.showShortSafe("Token登录过期了");
      return true;
    }

    return false;
  }

  class RequestCode {
    private int err;
    private String msg;

    public int getErr() {
      return err;
    }

    public void setErr(int err) {
      this.err = err;
    }

    public String getMsg() {
      return msg;
    }

    public void setMsg(String msg) {
      this.msg = msg;
    }
  }

}

okBuilder.addInterceptor(new TokenInterceptor()); //请求过期更换token