ASP.NET下载诸如word,txt,图片等

try
   {
   FullFileName = Server.MapPath(FileName);  //FileName--要下载的文件名
   FileInfo DownloadFile= new FileInfo(FullFileName);
  if(DownloadFile.Exists)
     {
     Response.Clear();
     Response.ClearHeaders();
     Response.Buffer=false;
     Response.ContentType="application/octet-stream";
     Response.AppendHeader("Content-Disposition","p_w_upload;filename="
    +HttpUtility.UrlEncode(DownloadFile.FullName,System.Text.Encoding.ASCII));

     Response.AppendHeader("Content-Length",DownloadFile.Length.ToString());
     Response.WriteFile(DownloadFile.FullName);
     Response.Flush();

     Response.End();
   }
  else{
    //文件不存在
   }
   }
catch{
  //文件不存在
}