Winform中Treeview实现按需加载的方法

List<string> m_Departments = new List<string>() { "湖北.黄石", "湖北.鄂州", "湖北.武汉" };
private void AddDepartMents(List<string> departments)
{
     if (m_Root == null)
     {
         var root = departments[0].Split('.')[0];
         m_Root = new TreeNode(root);
         m_Root.Tag = root;
         treeView1.Nodes.Add(m_Root);
     }
     foreach (var department in departments)
     {
         var parent = m_Root;
         var dts = department.Split('.');
         for (int i = 1; i < dts.Length; i++)
         {
             if (!m_OrgNodeManager.ContainsKey(dts[i]))
             {
                 var child = new TreeNode(dts[i],1,1);
                 child.Tag = dts[i];
                 child.ToolTipText = department;
                 m_OrgNodeManager.Add(dts[i], child);
                 parent.Nodes.Add(child);
                 parent = child;
             }
         }
         parent.Nodes.Add("");
     }
}

private void treeView1_BeforeExpand(object sender, TreeViewCancelEventArgs e)
{
     TreeNode curentNode = e.Node;
     if (curentNode.ImageIndex == 1)
     {
         curentNode.Nodes.Clear();
         foreach (var user in m_UserManager)
         {
             if (user.Value.ToString() == curentNode.ToolTipText.ToString())
             {
                 TreeNode userNode = new TreeNode(user.Key);
                 curentNode.Nodes.Add(userNode);
             }
         }
     }
}