如果要弹出下载对话框，加入以下程序即可：

                Response.Clear();
                HttpContext.Current.Response.ClearHeaders();
                HttpContext.Current.Response.AppendHeader("Expires ", System.DateTime.Now.AddMinutes(30).ToString());
                HttpContext.Current.Response.AppendHeader("Pragma ", "public ");
                HttpContext.Current.Response.AppendHeader("Cache-Control ", "must-revalidate,   post-check=0,   pre-check=0 ");
                HttpContext.Current.Response.AppendHeader("Cache-Control ", "public ");

                Response.AddHeader("Content-Disposition", "attachment; filename=auth.txt");

                Response.ContentType = "application/x-msdownload";

                //Response.BinaryWrite(buffer);    //二进制流输出

                Response.Write(oid);   //字符串输出
                HttpContext.Current.ApplicationInstance.CompleteRequest();

以上程序为打开记事本下载对话框，如果修改输出内容，可弹出word、excel等下载对话框。