web中将层次数据绑定到TreeView的实现

开始写xpnsoft的Web代码了，自己对web编程实在不熟悉，涉及到层次数据TreeVIew实现时，参照winform的方法去实现（http://blog.csdn.net/zwq78/archive/2008/05/18/2455889.aspx），但在web中，用继承方法自定义控件并不是件容易的事，只好另写了一个类，用代理的方法将层次数据绑定treeview的代码封装在该类中，程序如下：

Imports System.ComponentModel

Public Class tvCodeItem

    Private mValueMember As String
    Private mDisplayMember() As String
    Private mHasChild As Boolean
    Private mPidMember As String
    Private mCPtrMember As String
    Private mDataTable As DataTable
    Private mtv As TreeView

    Public Property PidMember() As String
        Get
            Return mPidMember
        End Get
        Set(ByVal Value As String)
            mPidMember = Value
        End Set
    End Property

    Public Property CPtrMember() As String
        Get
            Return mCPtrMember
        End Get
        Set(ByVal Value As String)
            mCPtrMember = Value
        End Set
    End Property

    Public Property ValueMember() As String
        Get
            Return mValueMember
        End Get
        Set(ByVal Value As String)
            mValueMember = Value
        End Set
    End Property

    Public Property DisplayMember() As String
        Get
            Return Join(mDisplayMember, SPLITSTRING)
        End Get
        Set(ByVal Value As String)
            mDisplayMember = Split(Value, SPLITSTRING)
        End Set
    End Property

    Public Property DataSource() As DataTable
        Get
            Return mDataTable
        End Get
        Set(ByVal Value As DataTable)
            mDataTable = Value
        End Set
    End Property

    Function GetValue(ByVal r As DataRow) As Object
        Return r(mValueMember)
    End Function

    Function GetDisplay(ByVal r As DataRow) As Object
        Dim i As Int32
        Dim temp As String = ""
        For i = 0 To mDisplayMember.Length - 1
            temp = temp & IIf(i > 0, LINKSTRING, "") & r(mDisplayMember(i))
        Next
        Return temp
    End Function

    Function GetPid(ByVal r As DataRow) As Object
        Return r(mPidMember)
    End Function

    Function GetCPtr(ByVal r As DataRow) As Boolean
        Return r(mCPtrMember)
    End Function

    Public Shadows Sub Init(ByVal collid As Int32, Optional ByVal dispmember As String = "") ', _

        If dispmember = "" Then
            dispmember = DefaultShowFields
        End If

        If collid = 0 Then Exit Sub
        If Me.CollectID = collid Then
            Exit Sub
        End If

        Dim dt As DataTable, dtsource As DataTable
        Dim filter As String = "collectid=" + collid.ToString
        cbase.GetCodeItemDataRows(collid) '并不是进入系统就加载了所有CodeItem，所以需要在每次使用前调用GetCodeItemDataRows
        dtsource = cbase.GetDataTable("codeitem")

        dt = dtsource.Clone
        Dim dr() As DataRow
        dr = dtsource.Select(filter)
        Dim i As Int32
        For i = 0 To dr.Length - 1
            dt.ImportRow(dr(i))
        Next
        With Me
            .PidMember = "pid"
            .CPtrMember = "cptr"
            .DisplayMember = dispmember
            .ValueMember = "id"
            '要在所有字段成员赋值完成后，再给datasource写入值。
            .DataSource = dt
        End With

        Me.FillTreeNode(Nothing, "pid=0")

        Me.CollectID = collid

    End Sub

    Private Sub FillTreeNode(ByRef pnode As TreeNode, ByVal filter As String)
        If pnode Is Nothing Then mtv.Nodes.Clear()
        Dim rows As DataRow() = Me.DataSource.Select(filter)
        Dim r As DataRow
        Dim newnode As myTreeNode
        For Each r In rows
            newnode = New myTreeNode(GetDisplay(r), GetValue(r), GetPid(r), GetCPtr(r))

            newnode.PopulateOnDemand = newnode.CPtr

            If pnode Is Nothing Then
                mtv.Nodes.Add(newnode)
            Else
                pnode.ChildNodes.Add(newnode)
            End If

        Next
    End Sub

    Private mCollectID As Int32

    Public Property CollectID() As Int32
        Get
            Return mCollectID
        End Get
        Set(ByVal Value As Int32)
            mCollectID = Value
        End Set
    End Property

    Public Sub New(ByVal tv As WebControls.TreeView)
        Me.mtv = tv
    End Sub

    Public Sub TreeNodePopulate(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.TreeNodeEventArgs)
        If e.Node.PopulateOnDemand Then
            FillTreeNode(e.Node, "pid=" + e.Node.Value.ToString)
        End If
    End Sub
End Class

客户端调用：

      Dim x As New tvCodeItem(Me.tvFilter)
      x.Init(collectid)
      Me.Session("tvcodeitem") = x

    Protected Sub tvFilter_TreeNodePopulate(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.TreeNodeEventArgs) Handles tvFilter.TreeNodePopulate
        Dim x As tvCodeItem = CType(Me.Session("tvcodeitem"), tvCodeItem)
        x.TreeNodePopulate(sender, e)
    End Sub

说明：

1、codeitem相当于所有的代码集合（数据字典），进入系统时并不是全部加载，是在需要的时候，从数据库加载（collectID=?）

2、将tv.TreeNodePopulate写在tvcodeitem中不会被触发，只有在客户端调用。