<a href="download.aspx?pth=xx/sss.wmv">点我</a>用一个download.aspxPageLoad中
string path = Request["pth"];
String FullFileName = Server.MapPath(path);
        FileInfo DownloadFile = new FileInfo(FullFileName);
        Response.Clear();
        Response.ClearHeaders();
        Response.Buffer = false;
        Response.ContentType = "application/octet-stream";
        Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(DownloadFile.FullName, System.Text.Encoding.UTF8));
        Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
        Response.WriteFile(DownloadFile.FullName);
        Response.Flush();
        Response.End();