Asp.net获取服务器指定文件夹目录文件并提供下载

string dirPath = HttpContext.Current.Server.MapPath("uploads/");
if (Directory.Exists(dirPath))
{
       //获得目录信息
       DirectoryInfo dir = new DirectoryInfo(dirPath);
       //获得目录文件列表
       FileInfo[] files = dir.GetFiles(".");
       string[] fileNames = new string[files.Length];

       //临时数据表
       DataTable dt = new DataTable();
       dt.Columns.Add("FileName");
      
       foreach (FileInfo fileInfo in files)
       {
    DataRow dr = dt.NewRow();
    dr["FileName"] = fileInfo.Name;
    dt.Rows.Add(dr);

       }
       Repeater1.DataSource = dt;
       Repeater1.DataBind();
}

if (e.CommandName == "down")
{
    try
    {
     string DownloadFileName = "~/uploads/" + e.CommandArgument.ToString();//文件路径
     string filepath = Server.MapPath(DownloadFileName);
     string filename = Path.GetFileName(filepath);
     FileInfo file = new FileInfo(filepath);
     Response.Clear();
     Response.ContentType = "application/octet-stream";
     Response.AddHeader("Content-Disposition", "attachment; filename=" + HttpUtility.UrlEncode(filename, System.Text.Encoding.UTF8));
     Response.AddHeader("Content-length", file.Length.ToString());
     Response.Flush();
     Response.WriteFile(filepath);
    }
    catch
    {
 Response.Write("<script>alert('没有找到下载的源文件')</script>");
    }
}