WinForm TreeView递归加载

public partial class Form1 : Form
    {
        List<China> Chlist = new List<China>();
        public Form1()
        {
            InitializeComponent();
            Chlist = new ChinaData().Select();
            TreeNode tn1 = new TreeNode("中国");
            tn1.Tag = "0001";
            NodesBind(tn1);
            treeView1.Nodes.Add(tn1);
        }
        public void NodesBind(TreeNode tn)
        {
            //lambda 表达式
            List<China> clist = Chlist.Where(a=>a.ParentAreaCode==tn.Tag.ToString()).ToList();
            foreach (China c in clist)
            {
                TreeNode tnn = new TreeNode(c.AreaName);
                tnn.Tag =c.AreaCode;
                NodesBind(tnn);//递归
                tn.Nodes.Add(tnn);
            }
         }
    }