右击/左击treeview，获取树节点

 private void treeView1_MouseDown(object sender, MouseEventArgs e)        {            TreeView dv = (TreeView)sender;            if (e.Button == MouseButtons.Right)            {                Point ClickPoint = new Point(e.X, e.Y);//获取单击位置                TreeNode CurrentNode = dv.GetNodeAt(ClickPoint);//检索位于指定点的树节点                if (CurrentNode != null)                {                    if (CurrentNode.Level == 2)//数节点位于的层次，下标从0开始                    {                        rightNodeCurrentText = CurrentNode.Parent.Parent.Text + CurrentNode.Parent.Text + CurrentNode.Text;//获取树节点的父节点                        CurrentNode.ContextMenuStrip = contextMenuStrip1;//获取与此树节点关联的快捷菜单，控件<span style="font-family: Arial, Helvetica, sans-serif;">contextMenuStrip1即为单击右键弹出来的菜单，里                                                                                                                                                      面的内容可以提前设置</span>                    }                    dv.SelectedNode = CurrentNode;                }            }            if (e.Button == MouseButtons.Left)            {                Point ClickPoint = new Point(e.X, e.Y);                TreeNode CurrentNode = dv.GetNodeAt(ClickPoint);                if (CurrentNode != null)                {                    if (CurrentNode.Level == 2)                    {                        update_gongneng = CurrentNode.Parent.Parent.Text;                        update_leixing = CurrentNode.Parent.Text;                        update_zhuangbei = CurrentNode.Text;                        leftNodeCurrentText = CurrentNode.Parent.Parent.Text + CurrentNode.Parent.Text + CurrentNode.Text;                    }                }            }        }