protected void btn_Download_Click(object sender, EventArgs e)
{
string strFileUploadPath = "Files/";
//从列表框控件中读取选择的文件名
string strFileName = lb_FileList.SelectedValue; //组合成物理路径
string strFilePhysicalPath = Server.MapPath("~/" + strFileUploadPath + strFileName);
Response.Clear();
Response.ContentType = "application/octet-stream";
Response.AddHeader("Content-Disposition", "attachment;FileName=" + HttpUtility.UrlEncode(strFileName, System.Text.Encoding.UTF8));
Response.WriteFile(strFilePhysicalPath);
Response.End();
}