asp.net TreeView与XML三步生成列表树

<?xml version="1.0" encoding="utf-8" ?>
<functions>
  <function name="商品发布" url="~/page/leaves/leave.aspx">
    <subfunction name="添加商品" url="~/page/leaves/leave.aspx">
    </subfunction>
    <subfunction name="添加商品" url="~/page/leaves/leave.aspx">
    </subfunction>
  </function>
  <function name="留言发布" url="~/page/leaves/leave.aspx">
    <subfunction name="添加留言" url="~/page/leaves/leave.aspx">
    </subfunction>
    <subfunction name="修改留言" url="~/page/leaves/leave.aspx">
    </subfunction>
  </function>
</functions>

/// <summary>
        /// 初始化功能树结构
        /// </summary>
        private void InitFunction()
        {
            XmlDocument xmldoc = new XmlDocument();
            string xmlPath = "~/adminFunction.xml";
            xmlPath = Server.MapPath(xmlPath);
            xmldoc.Load(xmlPath);
            XmlNode root = xmldoc.DocumentElement;

            foreach (XmlNode node in root.ChildNodes)
            {
                //获取父节点的信息显示(轻狂-书生)
                XmlElement x1 = node as XmlElement;
                string name = x1.GetAttribute("name");
                string url = x1.GetAttribute("url");
                TreeNode tn = new TreeNode();
                tn.Text = name;
                tn.NavigateUrl = url;
                foreach (XmlNode subnode in x1.ChildNodes)
                {
                    XmlElement subxmlEmt = subnode as XmlElement;
                    string subname = subxmlEmt.GetAttribute("name");
                    string suburl = subxmlEmt.GetAttribute("url");
                    TreeNode subtn = new TreeNode();
                    subtn.Text = subname;
                    subtn.NavigateUrl = suburl;
                    tn.ChildNodes.Add(subtn);

                }
                tvFunction.Nodes.Add(tn);

            }
        }