public string PostFunction(string url, Dictionary<string, string> parameters)
        {
            string serviceAddress = url;
            //HttpWebRequest类继承于WebRequest，并没有自己的构造函数，需通过WebRequest的Creat方法 建立，并进行强制的类型转换 
            HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
            request.ContentType = "application/json";
            request.Method = "POST";

            using (StreamWriter dataStream = new StreamWriter(request.GetRequestStream()))
            {
                dataStream.Write(parameters);
                dataStream.Close();
            }
            HttpWebResponse response = (HttpWebResponse)request.GetResponse();
            string encoding = response.ContentEncoding;
            if (encoding == null || encoding.Length < 1)
            {
                encoding = "UTF-8"; //默认编码  
            }
            //解析josn

            Stream myResponseStream = response.GetResponseStream();
            using (var gStream = new GZipStream(myResponseStream, CompressionMode.Decompress))
            {
                //Encoding.GetEncoding("UTF-8")转码
                StreamReader myStreamReader = new StreamReader(gStream, Encoding.GetEncoding("UTF-8"));
                string retString = myStreamReader.ReadToEnd();
                JObject jo = JObject.Parse(retString);
                myStreamReader.Close();
                response.Close();
                myResponseStream.Close();
                return retString;
            }
}