private TreeNode root1;
        private TreeNode root2;
        private TreeNode root3;
        private TreeNode root4;
        public Form1()
        {
            InitializeComponent();
            Load += Form1_Load;
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            treeView1.Font = new Font(treeView1.Font.FontFamily, 14.5f);
            root1 = treeView1.Nodes.Add("FirstRoot");
            root2 = treeView1.Nodes.Add("SecondRoot");
            root3 = treeView1.Nodes.Add("ThirdRoot");
            root4 = treeView1.Nodes.Add("FourRoot");      
        }

  private void Form1_Load(object sender, EventArgs e)
        {
            treeView1.Font = new Font(treeView1.Font.FontFamily, 14.5f);
            root1 = treeView1.Nodes.Add("FirstRoot");
            root2 = treeView1.Nodes.Add("SecondRoot");
            root3 = treeView1.Nodes.Add("ThirdRoot");
            root4 = treeView1.Nodes.Add("FourRoot");
            Root1AddChild();
        }

        private void Root1AddChild()
        {
            TreeNode root1Child_1=new TreeNode("FirstChild_1");
            TreeNode root1Child_2 = new TreeNode("FirstChild_2");
            TreeNode root1Child_3 = new TreeNode("FirstChild_3");
            TreeNode root1Child_4 = new TreeNode("FirstChild_4");
            root1.Nodes.Add(root1Child_1);
            root1.Nodes.Add(root1Child_2);
            root1.Nodes.Add(root1Child_3);
            root1.Nodes.Add(root1Child_4);
        }

 /// <summary>
        /// Root增加子节点
        /// </summary>
        private void Root1AddChild()
        {
            TreeNode root1Child_1=new TreeNode("FirstChild_1");
            TreeNode root1Child_2 = new TreeNode("FirstChild_2");
            TreeNode root1Child_3 = new TreeNode("FirstChild_3");
            TreeNode root1Child_4 = new TreeNode("FirstChild_4");
            root1Child_1.ForeColor = Color.Blue;   //节点字体颜色
            root1Child_2.ForeColor = Color.Blue;
            root1Child_3.ForeColor = Color.Blue;
            root1Child_4.ForeColor = Color.Blue;
            root1.Nodes.Add(root1Child_1);
            root1.Nodes.Add(root1Child_2);
            root1.Nodes.Add(root1Child_3);
            root1.Nodes.Add(root1Child_4);
            FirstChildAddChild(root1Child_1);
        }
         /// <summary>
         /// 子节点下再增加 子节点
         /// </summary>
         /// <param name="root1Child_1"></param>
        private void FirstChildAddChild(TreeNode root1Child_1)
        {
            TreeNode grandChild1 = new TreeNode("GrandChild_1");
            TreeNode grandChild2 = new TreeNode("GrandChild_2");
            TreeNode grandChild3 = new TreeNode("GrandChild_3");
            TreeNode grandChild4 = new TreeNode("GrandChild_4");
            grandChild1.ForeColor = Color.Red;   //节点字体颜色
            grandChild2.ForeColor = Color.Red;
            grandChild3.ForeColor = Color.Red;
            grandChild4.ForeColor = Color.Red;
            root1Child_1.Nodes.Add(grandChild1);
            root1Child_1.Nodes.Add(grandChild2);
            root1Child_1.Nodes.Add(grandChild3);
            root1Child_1.Nodes.Add(grandChild4);  
        }

     /// <summary>
         /// 子节点下再增加 子节点
         /// </summary>
         /// <param name="root1Child_1"></param>
        private void FirstChildAddChild(TreeNode root1Child_1)
        {
            TreeNode grandChild1 = new TreeNode("GrandChild_1");
            TreeNode grandChild2 = new TreeNode("GrandChild_2");
            TreeNode grandChild3 = new TreeNode("GrandChild_3");
            TreeNode grandChild4 = new TreeNode("GrandChild_4");

            grandChild1.Tag = "Tag可以存放数据，类型为Object";  

            grandChild1.ForeColor = Color.Red;   //节点字体颜色
            grandChild2.ForeColor = Color.Red;
            grandChild3.ForeColor = Color.Red;
            grandChild4.ForeColor = Color.Red;
            root1Child_1.Nodes.Add(grandChild1);
            root1Child_1.Nodes.Add(grandChild2);
            root1Child_1.Nodes.Add(grandChild3);
            root1Child_1.Nodes.Add(grandChild4);  
        }

        private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            /*
               e.Node  == 当前点击的节点
               e.Node.Level ==当前点击节点深度（层）  从根节点0开始 =》ROOT=0
             */
            if (e.Node.Level==2)  
            {
                if (e.Node.Tag!=null)
                {
                    MessageBox.Show(e.Node.Tag.ToString());
                }
            }
        }

 private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
        {
            /*
               e.Node  == 当前点击的节点
               e.Node.Level ==当前点击节点深度（层）  从根节点0开始 =》ROOT=0
             */
            if (e.Node.Level==2)  
            {
                if (e.Node.Tag!=null)
                {
                    MessageBox.Show(e.Node.Tag.ToString());
                }
            }
            if (e.Button == MouseButtons.Right)
            {
                e.Node.ContextMenuStrip = contextMenuStrip1;    
            }
        }