#region 下载文件按钮事件
    protected void btn_DownLoad_Click(object sender, EventArgs e)
    {
        //从web.config读取文件上传路径
        string strFileUploadPath = ConfigurationManager.AppSettings["FileUplodePath"].ToLower();
        //从列表框中读取选择的文件
        string strFileName = lb_FileList.SelectedValue;
        //组合成物理路径
        string FullFileName = Server.MapPath(strFileUploadPath + "/") + strFileName;
        FileInfo fi = new FileInfo(FullFileName);
        Response.Clear();
        Response.ClearHeaders();
        Response.Buffer = false;
        Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(Path.GetFileName(FullFileName), System.Text.Encoding.UTF8));
        Response.AppendHeader("Content-Length", fi.Length.ToString());
        Response.WriteFile(FullFileName);
        Response.Flush();
        Response.End();
     
    }
    #endregion