Asp.net 动态为TreeView创建结点

<? xml version="1.0" encoding="utf-8"  ?>
< siteMap  xmlns ="http://schemas.microsoft.com/AspNet/SiteMap-File-1.0"   >
     < siteMapNode  url ="~/TreeView/Default.aspx"  title ="首页"   description ="" >
         < siteMapNode  url ="http://www.baidu.com"  title ="百度"   description ="" >
             < siteMapNode  url ="http://zhidao.baidu.com"  title ="百度知道"  description ="百度知道" ></ siteMapNode >
             < siteMapNode  url ="http://mp3.baidu.com"  title ="百度音乐"  description ="百度音乐" ></ siteMapNode >
             < siteMapNode  url ="http://news.baidu.com"  title ="百度新闻"  description ="百度新闻" ></ siteMapNode >
         </ siteMapNode >

         < siteMapNode  url ="http://www.google.com.hk"  title ="谷歌"   description ="" >
             < siteMapNode  url ="http://ditu.google.com"  title ="谷歌地图"  description ="谷歌地图" ></ siteMapNode >
         </ siteMapNode >
         < siteMapNode  url ="http://www.cnblogs.com"  title ="博客园"  description ="博客园" >
             < siteMapNode  url ="http://zhuiyi.cnblogs.com"  title ="我的博客"  description ="" ></ siteMapNode >
         </ siteMapNode >
     </ siteMapNode >
</ siteMap >

< asp:TreeView  ID ="TreeView1"  runat ="server"  DataSourceID ="SiteMapDataSource1"  ImageSet ="BulletedList4" >
         </ asp:TreeView >
         < asp:SiteMapDataSource  ID ="SiteMapDataSource1"  runat ="server"   />
         < asp:Button  ID ="btnAddNode"  runat ="server"  Text ="动态添加结点"  
            onclick ="btnAddNode_Click"    />

  protected   void  btnAddNode_Click( object  sender, EventArgs e)
        {
            TreeNode tn  =   new  TreeNode();
            tn.Text  =   " 我的博客 " ;
            tn.NavigateUrl  =   " http://zhuiyi.cnblogs.com " ;

            TreeNode mytreenode  =  TreeView1.FindNode( " 首页 " );
            TreeView1.FindNode( " 首页/博客园 " ).ChildNodes.Add(tn);
        }