/// <summary>
        ///接口获取openid和session_key
        /// </summary>
        /// <param name="code">前台通过调用login接口获取到的code</param>
        /// <param name="anonymous_code">前台通过调用login接口获取到的anonymous_code</param>
        /// <returns></returns>
        public string LoginGetopenid(string code, string anonymous_code)//未效验
        {

            //按照规则填写参数
            string appid = "***********";
            string secret = "*****************************************";

            //地址（这里对地址和参数进行了分开处理，url为地址，postString为参数） 
            string url = "https://developer.toutiao.com/api/apps/jscode2session";
            //这里即为传递的参数，可以用工具抓包分析，也可以自己分析，主要是form里面每一个name都要加进来
            string GETString = "appid=" + appid + "&secret=" + secret + "&code=" + code + "&anonymous_code=" + anonymous_code;
            //编码，尤其是汉字，事先要看下抓取网页的编码方式  
            byte[] GETData = Encoding.UTF8.GetBytes(GETString);

            //初始化WebClient类（提供将数据发送到url的资源，及从这样的资源接收数据）
            WebClient webClient = new WebClient();
            ////采取POST方式必须加的header，如果改为GET方式的话就去掉这句话即可
            //webClient.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

            string requestUrl = url + "?" + GETString;
            //得到解码的返回字符流
            string responseData = Encoding.UTF8.GetString(webClient.DownloadData(requestUrl));
            //解码后将数据转换为Json类型的object
            JObject returnJSON = (JObject)JsonConvert.DeserializeObject(responseData);
            //赋值如果未获取到openid则登录失败，否则成功
            dynamic objJson = new ExpandoObject();
            if (returnJSON["openid"] != null || returnJSON["openid"].ToString() != "")
            {
                int error = Convert.ToInt32(returnJSON["error"]);
                string openid = returnJSON["openid"].ToString();
                string session_key = returnJSON["session_key"].ToString();
                string anonymous_openid = returnJSON["anonymous_openid"].ToString();
                
            }
            else
            {
                //为空则返回失败
            }
            
            return “”;
        }