C#使用post方式提交json数据

            string _url = "http://192.168.0.135:888/sqjz/fxry/fxry/up";
            string jsonParam = "{\"sqjzrybh\":\"A001\",\"sfzh\":\"130533196874589652\",\"xm\":\"王涛\"}";
            var request = (HttpWebRequest)WebRequest.Create(_url);
            request.Method = "POST";
            request.ContentType = "application/json;charset=UTF-8";
            var byteData = Encoding.UTF8.GetBytes(jsonParam);
            var length = byteData.Length;
            request.ContentLength = length;
            var writer = request.GetRequestStream();
            writer.Write(byteData, 0, length);
            writer.Close();
            var response = (HttpWebResponse)request.GetResponse();
            var responseString = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8")).ReadToEnd();
            MessageBox.Show(responseString.ToString());