treeview目录树问题
private void Form1_Load(object sender, EventArgs e)
  {
  DriveInfo[] drivers = DriveInfo.GetDrives();//获取计算机上的所有逻辑驱动器名称
  foreach (var item in drivers)
  {
  treeView1.Nodes.Add(item.ToString());
  }
这里获得了盘符，也加载了，但是下面的代码怎么修改才能展开对应的子目录，谢谢
private void treeView1_BeforeExpand(object sender, TreeViewCancelEventArgs e)
  {
  e.Node.Nodes.Cast<TreeNode>().ToList().ForEach(x =>
  {
  try
  {
  if (x.Nodes.Count == 0)
  {
  TreeNode[] nodes = new TreeNode[] { };
  if (x.Tag.GetType() == typeof(DriveInfo))
  {
  var item = x.Tag as DriveInfo;
  nodes = Directory.GetDirectories(item.Name)
  .Select(y => new DirectoryInfo(y))
  .Select(y => new TreeNode(y.Name) { Tag = y })
  .ToArray();
  }
  if (x.Tag.GetType() == typeof(DirectoryInfo))
  {
  var item = x.Tag as DirectoryInfo;
  nodes = Directory.GetDirectories(item.FullName)
  .Select(y => new DirectoryInfo(y))
  .Select(y => new TreeNode(y.Name) { Tag = y })
  .ToArray();
  }
  x.Nodes.AddRange(nodes);
  }
  }
  catch { }
  });
  }

------解决方案--------------------
http://www.cnblogs.com/sndnnlfhvk/archive/2011/03/31/2001065.html之前找资料的
------解决方案--------------------
如下修改即可

C# code

 private void Form1_Load(object sender, EventArgs e)
            {
                DriveInfo[] drivers = DriveInfo.GetDrives();//获取计算机上的所有逻辑驱动器名称
                foreach (var item in drivers)
                {
                    TreeNode tn = new TreeNode();
                    tn.Tag = item;
                    tn.Text = item.ToString();
                    treeView1.Nodes.Add(tn);
                }
            }
private void treeView1_NodeMouseClick(object sender, TreeNodeMouseClickEventArgs e)
            {
                TreeNode tn = e.Node;

                try
                {
                    if (tn.Nodes.Count == 0)
                    {
                        TreeNode[] nodes = new TreeNode[] { };
                        if (tn.Tag.GetType() == typeof(DriveInfo))
                        {
                            var item = tn.Tag as DriveInfo;
                            nodes = Directory.GetDirectories(item.Name)
                            .Select(y => new DirectoryInfo(y))
                            .Select(y => new TreeNode(y.Name) { Tag = y })
                            .ToArray();
                        }
                        if (tn.Tag.GetType() == typeof(DirectoryInfo))
                        {
                            var item = tn.Tag as DirectoryInfo;
                            nodes = Directory.GetDirectories(item.FullName)
                            .Select(y => new DirectoryInfo(y))
                            .Select(y => new TreeNode(y.Name) { T