DropDownList1.Items.Add(New ListItem(classname, classid))

            Dim sonparentid As Integer = Integer.Parse(classid)

            Dim blank As String = "├"

            '递归子分类方法

            BindNode(sonparentid, dt, blank)

        Next

        DropDownList1.DataBind()

    End Sub

    '绑定子分类

    Private Sub BindNode(ByVal parentid As Integer, ByVal dt As DataSet, ByVal blank As String)

        Dim drs As DataRow() = dt.Tables(0).Select("parentid=" & parentid)

        For Each dr As DataRow In drs

            Dim classid As String = dr("catalogid").ToString()

            Dim classname As String = dr("catalogName").ToString()

            classname = blank + classname

            DropDownList1.Items.Add(New ListItem(classname, classid))

            Dim sonparentid As Integer = Integer.Parse(classid)

            Dim blank2 As String = blank + "─"

            BindNode(sonparentid, dt, blank2)

         Next

    End Sub

4.3  填充树形控件

Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        If (Not IsPostBack) Then