递归遍历XML生成树

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Xml;
public partial class Default_aspx
{
 void Page_Load(object sender, EventArgs e)
 {

  string xmlstr = "<?xml version=\"1.0\"?><root><Note NodeName=\"的1\"><Note NodeName=\"的2\"><Note NodeName=\"的3\" /><Note NodeName=\"的4\" /></Note><Note NodeName=\"的5\" /></Note><Note NodeName=\"的6\"><Note NodeName=\"的7\"><Note NodeName=\"的8\" /><Note NodeName=\"的9\" /></Note><Note NodeName=\"的10\" /></Note></root>";
  IterateXml(xmlstr);
 }
/*
 <?xml version=\"1.0\"?><root><Note NodeName=\"的1\"><Note NodeName=\"的2\"><Note NodeName=\"的3\" /><Note NodeName=\"的4\" /></Note><Note NodeName=\"的5\" /></Note><Note NodeName=\"的6\"><Note NodeName=\"的7\"><Note NodeName=\"的8\" /><Note NodeName=\"的9\" /></Note><Note NodeName=\"的10\" /></Note></root>"
 */
 private void IterateXml(string xmlstr)
 {
  XmlDocument xmldoc = new XmlDocument();

  xmldoc.LoadXml(xmlstr);
  XmlNode worknode;
  TreeNode rootnode;
  for (int i = 0; i < xmldoc.DocumentElement.ChildNodes.Count; i++)
  {
   worknode = xmldoc.DocumentElement.ChildNodes[i];
   if (worknode.ChildNodes.Count > 0)
    rootnode = IterateChild(worknode);
   else
    rootnode = new TreeNode(worknode.Name);
   this.TreeView1.Nodes.Add(rootnode);   
  }
 }
 private TreeNode  IterateChild(XmlNode rootnode)
 {
  XmlNode worknode = rootnode;//当前遍历的节点

  System.Web.UI.WebControls.TreeNode retnode = new TreeNode(worknode.Attributes["NodeName"].Value); ;//要返回的树节点
  TreeNode newch;//中间树节点

  if (worknode.ChildNodes.Count < 1)
  {//没有子节点,生成一个树节点返回
   newch = new TreeNode(worknode.Attributes["NodeName"].Value);
   retnode = newch;
  }
  else //有子节点，调用递归
  {
   for (int i = 0; i < worknode.ChildNodes.Count; i++)
   {
    retnode.ChildNodes.Add(IterateChild(worknode.ChildNodes[i]));
   }
  }

  return retnode;
 }
}