[ASP.NET]下载txt格式的文件

string destFileName = "temp.txt";
destFileName = Server.MapPath(".") + "\\" + destFileName;
destFileName = Server.UrlDecode(destFileName);
if (File.Exists(destFileName))
{
FileInfo fi = new FileInfo(destFileName);
Response.Clear();
Response.ClearHeaders();
Response.Buffer = false;
Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(Path.GetFileName(destFileName), System.Text.Encoding.UTF8));
Response.AppendHeader("Content-Length", fi.Length.ToString());
Response.ContentType = "application/octet-stream";
Response.WriteFile(destFileName);
Response.Flush();
Response.End();
}