vb.net如何递归treeview所有节点

Public Class Form1
    Dim targetStr As String = "a123" '查询目标节点名
    Dim allNodes As New ArrayList
    '遍历并定位节点
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        get_n(TreeView1.Nodes) '获取所有节点的集合（mnodes)
        For Each ntxt As TreeNode In allNodes
            If ntxt.Text.IndexOf(targetStr) >= 0 Then
                TreeView1.SelectedNode = ntxt '打开目标节点
                TreeView1.Focus()
            End If
        Next
    End Sub
    '遍历现有的所有节点并存入mnodes集合
    Private Sub get_n(ByVal cn As TreeNodeCollection)
        Dim cnodes As TreeNode
        For Each tmp As TreeNode In cn
            If tmp.Nodes.Count > 0 Then
                allNodes.Add(tmp)
                cnodes = tmp
                get_n(cnodes.Nodes)
            Else
                allNodes.Add(tmp)
            End If
        Next
    End Sub

    Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
        MsgBox(TreeView1.Nodes.IndexOf(New TreeNode("a123")))
    End Sub

    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load
        With TreeView1
            .Nodes.Add("节点1")
            .Nodes.Add("节点2")
            .Nodes(0).Nodes.Add("子节点1")
            .Nodes(0).Nodes.Add("子节点2")
            .Nodes(1).Nodes.Add("子节点3")
            .Nodes(1).Nodes(0).Nodes.Add("子节点4")
            .Nodes(1).Nodes(0).Nodes.Add("a123") '目标节点
        End With

    End Sub
End Class

以上是示例代码。

该示例代码预先在treeview1控件中添加若干个分级子节点，其中添加一个名为“a123”的目标节点。按下<button1>按钮遍历所有预先添加的节点集合并选择<a123>节点。