下面是导出方法的代码


 private void WriteFile(string str_fileName, Stream stream)
        {
            HttpContext.Current.Response.Clear();
            HttpRequest _Request = HttpContext.Current.Request;
            HttpResponse _Response = HttpContext.Current.Response;
            BinaryReader br = new BinaryReader(stream);
            _Response.AddHeader("Accept-Ranges", "bytes");
            _Response.Buffer = false;
            long fileLength = stream.Length;
            long startBytes = 0;

            int pack = 10240; //10K bytes
            //int sleep = 200; //每秒5次 即5*10K bytes每秒
            int sleep = (int)Math.Floor(Convert.ToDouble(1000 * pack / 1024000)) + 1;
            if (_Request.Headers["Range"] != null)
            {
                _Response.StatusCode = 206;
                string[] range = _Request.Headers["Range"].Split(new char[] { '=', '-' });
                startBytes = Convert.ToInt64(range[1]);
            }
            _Response.AddHeader("Content-Length", (fileLength - startBytes).ToString());
            if (startBytes != 0)
            {
                _Response.AddHeader("Content-Range", string.Format(" bytes {0}-{1}/{2}", startBytes, fileLength - 1, fileLength));
            }
            _Response.AddHeader("Connection", "Keep-Alive");
            _Response.ContentType = "application/vnd.ms-excel";
            _Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(str_fileName, System.Text.Encoding.UTF8));

            br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
            int maxCount = (int)Math.Floor(Convert.ToDouble((fileLength - startBytes) / pack)) + 1;
            for (int i = 0; i < maxCount; i++)
            {
                if (_Response.IsClientConnected)
                {
                    _Response.BinaryWrite(br.ReadBytes(pack));
                    Thread.Sleep(sleep);
                }
                else
                {
                    i = maxCount;
                }
            }
        }