[ASP.NET] 服务器端下载文件实现

            string _fileName = HttpContext.Current.Server.MapPath("~\\report\\FactReports\\") + e.Item.Cells[0].Text.Trim(); //服务器端文件路径
            //建立文件对象
            FileStream myFile = new FileStream(_fileName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
            //建立流读对象
            BinaryReader br = new BinaryReader(myFile);
            Response.AddHeader("Accept-Ranges", "bytes");
            Response.Buffer = false;
            long fileLength = myFile.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(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/octet-stream";
            Response.AddHeader("Content-Disposition","attachment;filename=" + HttpUtility.UrlEncode(_fileName,System.Text.Encoding.UTF8) );

            br.BaseStream.Seek(startBytes, SeekOrigin.Begin);
            int maxCount = (int) Math.Floor((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;

                }
            }
            myFile.Close();
            br.Close();
            Response.End();