public static string HttpPostJson(string url, string postStr, int timeOut, string charset)
        {
            HttpWebRequest wreq = null;
            HttpWebResponse res = null;
            string strRst = "";

            #region http web request

            Encoding ecd = Encoding.GetEncoding(charset);

            byte[] data = ecd.GetBytes(postStr);
            wreq = (HttpWebRequest)WebRequest.Create(url);
            wreq.Timeout = timeOut * 1000;
            wreq.ReadWriteTimeout = timeOut * 1000;
            wreq.Method = "POST";
            wreq.KeepAlive = false;
            wreq.ContentType = "application/json;charset=utf-8";
            wreq.ServicePoint.Expect100Continue = false; //当服务器恢复正常时，访问已经是200时，这个线程还是返回操作超时

            wreq.ContentLength = data.Length;
            using (Stream putStream = wreq.GetRequestStream())
            {
                putStream.Write(data, 0, data.Length);
            }

            res = wreq.GetResponse() as HttpWebResponse;
            byte[] by = new byte[800];
            using (Stream stream = res.GetResponseStream())
            {
                int size = 1024;
                int read = 0;
                using (MemoryStream ms = new MemoryStream())
                {
                    byte[] buffer = new byte[size];
                    do
                    {
                        read = stream.Read(buffer, 0, size);
                        ms.Write(buffer, 0, read);
                    } while (read > 0);

                    by = ms.ToArray();
                }
            }

            strRst = ecd.GetString(by);

            if (res != null)
                res.Close();
            if (wreq != null)
                wreq.Abort();//主动释放

            #endregion

            return strRst;
        }

textBox2.Text = CommonUtils.MU.HttpPostJson(url,textBox1.Text,30,"UTF-8");