/// <summary>
        /// 上传
        /// </summary>
        /// <param name="fileName"></param>
        /// <param name="fileStream"></param>
        public void FileUpload(string fileName, Stream fileStream)
        {

            FileStream fileToupload = new FileStream("D:\\FileUpload\\" + fileName, FileMode.Create);

            int _speed = 1024 * 1024; // 1M/S
            int pack = 10240; //10K bytes  
            byte[] bytearray = new byte[pack];
            double limit = 1000 / (_speed / pack); // 限速时每个包的时间

            int bytesRead, totalBytesRead = 0;
            do
            {
                Stopwatch wa = new Stopwatch();
                wa.Restart();
                bytesRead = fileStream.Read(bytearray, 0, bytearray.Length);
                totalBytesRead += bytesRead;
                wa.Stop();
                if (wa.ElapsedMilliseconds < limit) //如果实际带宽小于限制时间就不需要等待
                {
                    Thread.Sleep((int)(limit - wa.ElapsedMilliseconds));
                }
               
            } while (bytesRead > 0);

            fileToupload.Write(bytearray, 0, bytearray.Length);
            fileToupload.Close();
            fileToupload.Dispose();
        }