这是我写的代码：

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            TreeNode node = new TreeNode();   //这里是创建一个根节点
            node.Text = "";
            TreeView1.Nodes.Add(node);
            ////node.Tag = 0;//给根结点赋值0;
            CreateChildTree(node, 3);    //调用创建树的方法
            TreeView1.ExpandAll();

        }
    }

    protected void CreateChildTree(TreeNode parentNode, int ParentNodeId)
    {
        IList<ChildNodeInfo> NodesList = ChildNodeManager.ShowNodesList(ParentNodeId);
        foreach (ChildNodeInfo cn in NodesList)
        {
            ContentInfo ci = ContentManager.GetContentByPId(cn.Id);
            TreeNode myNode = new TreeNode(cn.Title);
            myNode.Value = cn.Id.ToString();
            if (ci != null)
            {
                string url = "jxzx_xx.aspx?TypeId=" + cn.NodeTypeId + "&PId=" + cn.Id+"";
                myNode.NavigateUrl = url;
            }
            parentNode.ChildNodes.Add(myNode);
            CreateChildTree(myNode, Convert.ToInt32(cn.Id));  //递归显示出子节点
        }
    }