文件下载

public partial class DownloadSL : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string fileName = "Silverlight.exe";
            string filePath = Server.MapPath(@"Files\Silverlight.exe");
            if (!ResponseFile(Request, Response, fileName, filePath, 1024000))
            {
                string downloadUrl = @"<a href='http://go.microsoft.com/fwlink/?LinkID=149156&v=4.0.50401.0' style='text-decoration:none'>
 			                             <img src='" + Server.MapPath(@"images\SLMedallion_CHS.png") + @"' alt='Get Microsoft Silverlight' style='border-style:none'/>
		                               </a>";
                Response.Write(string.Format("从本站下载silverlight安装文件失败,请从{0}下载！", downloadUrl));
            }
        }

        public static bool ResponseFile(HttpRequest _Request, HttpResponse _Response, string _fileName, string _fullPath, long _speed)
        {
            try
            {
                FileStream myFile = new FileStream(_fullPath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                BinaryReader br = new BinaryReader(myFile);
                try
                {
                    _Response.AddHeader("Accept-Ranges", "bytes");
                    _Response.Buffer = false;
                    long fileLength = myFile.Length;
                    long startBytes = 0;

                    double pack = 10240; //10K bytes
                    //int sleep = 200;   //每秒5次   即5*10K bytes每秒
                    int sleep = (int)Math.Floor(1000 * pack / _speed) + 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(int.Parse(pack.ToString())));
                            Thread.Sleep(sleep);
                        }
                        else
                        {
                            i = maxCount;
                        }
                    }
                    return true;
                }
                catch
                {
                    return false;
                }
                finally
                {
                    br.Close();

                    myFile.Close();
                }
            }
            catch
            {
                return false;
            }
        }

    }