protected void Page_Load(object sender, EventArgs e)

    {

        if (!IsPostBack)

        {

            if (Request.QueryString["filename"] != null && Request.QueryString["path"] != null)

            {

                string filename = Request.QueryString["filename"];

                string path = Request.QueryString["path"];

                if (!string.IsNullOrEmpty(filename))

                {

                    string filePath = Server.MapPath("~" + path) + filename;

                    FileInfo fileInfo = new FileInfo(filePath);

                    if (fileInfo.Exists == true)

                    {

                        const long ChunkSize = 102400;//100K 每次读取文件，只读取100K，这样可以缓解服务器的压力

                        byte[] buffer = new byte[ChunkSize];

                        Response.Clear();

                        FileStream iStream = File.OpenRead(filePath);

                        long dataLengthToRead = iStream.Length;//获取下载的文件总大小

                        Response.ContentType = "application/octet-stream";

                        Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename));

                        while (dataLengthToRead > 0 && Response.IsClientConnected)

                        {

                            int lengthRead = iStream.Read(buffer, 0, Convert.ToInt32(ChunkSize));//读取的大小

                            Response.OutputStream.Write(buffer, 0, lengthRead);

                            Response.Flush();

                            dataLengthToRead = dataLengthToRead - lengthRead;

                        }

                        Response.Close();

                    }

                }

            }

        }

    }

 

 

调用： lnk_down.HRef = "Download.aspx?filename=" + 文件名+ "&path=" + 文件路径;