<script type="text/javascript">
        function upload(a){
          var path = a.attr('value');
          var data ={ url: base64encode(path) };
       
                 $.post("/Handler/DownLoad.ashx?r="+ Math.random(),{ url: base64encode(path) },function(date){

                        if(date == "0"){
                             alert("下载失败!");
                             return ;
                        }
                        if(date == "1"){
                             alert("下载成功!");
                             return ;
                        }
                        if(date == "-1"){
                             alert("文件不存在!");
                             return ;
                        }
                 })
        }
    </script>

  public static void TransferFile(string filepath)
        {
           
            StreamWriter sw = new StreamWriter(@"E:\ENDadmin\ndfile\2.txt", true, Encoding.UTF8);
          
            try
            {
                FileStream filestream = new FileStream(filepath, FileMode.Open, System.IO.FileAccess.Read, System.IO.FileShare.Read);

                

                sw.WriteLine("文件完成读取");
                long filesize = filestream.Length;
                //   sw.WriteLine("查询大小完成");
                //让客户端浏览器正确识别这个文件的类型和文件大小
                string filename = System.IO.Path.GetFileName(filepath).ToLower();
                sw.WriteLine("识别大小完成");

                HttpContext.Current.Response.ContentType = "application/octet-stream";
                sw.WriteLine("制定类型完成");
                HttpContext.Current.Response.AddHeader("Content-Disposition", "attachment; filename=\"" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8) + "\";");
                sw.WriteLine("文件位置制定完成");
                HttpContext.Current.Response.AddHeader("Content-Length", filesize.ToString());

                sw.WriteLine("长度制定完成");
                //将文件中的数据发送到客户端
                byte[] filebuffer = new byte[filesize];
                sw.WriteLine("获取文件数据");
                filestream.Read(filebuffer, 0, (int)filesize);
                sw.WriteLine("发送ING");
                HttpContext.Current.Response.BinaryWrite(filebuffer);
                HttpContext.Current.Response.Flush();
                sw.WriteLine("发送完成");
                filestream.Close();
                sw.WriteLine("释放");
          
                HttpContext.Current.ApplicationInstance.CompleteRequest();
            }
            catch (Exception ex)
            {

                sw.WriteLine("报错了！" + ex.Message);
                sw.WriteLine("报错了！" + ex.TargetSite);

            }
            finally
            {
                sw.Flush();
                sw.Close();
            }
        }