VB.NET中层次数据绑定TreeView的实现

Protected Property DataSource() As Object
　Get
　　Return mDataView
　End Get

　Set(ByVal Value As Object)
　　If Value Is Nothing Then
　　Else
　　　mDataView = Value
　　　cm = CType(Me.BindingContext(mDataView), CurrencyManager)
　　　UpdateTreeView()
　　End If
　End Set
End Property

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

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

'注意，这几个属性都是保护成员，必须在Init事件中设置:

Public Sub Init(ByVal dispmember As String, ByVal valuemember As String, ByVal pidmember As String, ByVal cptrmember As String, ByVal datasource As DataView)
　Me.ValueMember = valuemember
　Me.DisplayMember = dispmember
　Me.PidMember = pidmember
　Me.CPtrMember = cptrmember
　Me.DataSource = datasource
　'取value最大值，新增时将value+1，保证关健值唯一。
　Me.mDataView.Sort = Me.ValueMember
　Me.m_MaxID = Me.GetValue(Me.mDataView.Count - 1)
End Sub

Protected Overridable Function GetDisplay(ByVal Index As Integer) As Object
　Dim i As Integer
　Dim temp As String = ""
　For i = 0 To mDisplayMember.Length - 1
　　temp = temp & IIf(i > 0, LinkChar, "") & mDataView(Index)(mDisplayMember(i))
　Next
　Return temp
End Function

Private Sub FillTree(ByRef pnode As myTreeNode, Optional ByVal filter As String = "")
　mDataView.RowFilter = filter
　Dim i As Integer, icol As Integer
　Dim newnode As myTreeNode
　RemoveHandler cm.PositionChanged, AddressOf cm_PositionChanged
　Me.BeginUpdate()
　For i = 0 To mDataView.Count() - 1
　　newnode = New myTreeNode(GetDisplay(i), GetValue(i), GetPid(i), GetCPtr(i))
　　'当有子结点时，为这个结点添加一个空子结点
　　If newnode.CPtr Then
　　　Dim nullnode As New myTreeNode()
　　　nullnode.Value = NoExpandNodeValue
　　　newnode.Nodes.Add(nullnode)
　　End If
　　If pnode Is Nothing Then
　　　Me.Nodes.Clear()
　　　Me.Nodes.Add(newnode)
　　Else
　　　pnode.Nodes.Add(newnode)
　　End If
　Next
　Me.EndUpdate()
　mDataView.RowFilter = ""
　AddHandler cm.PositionChanged, AddressOf cm_PositionChanged
End Sub

Private Sub dbTreeView_BeforeExpand(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewCancelEventArgs) Handles MyBase.BeforeExpand
　'当是新增结点引起BeforeExpand事件时，直接退出。
　If ExpandWhenAddNode Then Exit Sub
　'在展开结点前更新子结点
　Dim currentnode As myTreeNode = CType(e.Node, myTreeNode)
　With currentnode
　　.Nodes.Clear()
　　FillTree(currentnode, mPidMember & "= " & CInt(.Value))
　End With
End Sub

Private Sub dbTreeView_AfterSelect(ByVal sender As Object, ByVal e As System.Windows.Forms.TreeViewEventArgs) Handles MyBase.AfterSelect

　If e.Node Is Nothing Then Exit Sub
　'定位到position
　cm.Position = GetPosition(CType(e.Node, myTreeNode).Value)
　If AllowEdit Then
　　oldNode = e.Node
　　oldPos = cm.Position
　End If
End Sub

Public Sub cm_PositionChanged(ByVal sender As Object, ByVal e As System.EventArgs)
　If CType(Me.SelectedNode, myTreeNode).Value <> GetValue(cm.Position) Then
　　Debug.WriteLine("Current node isn't correct point to currencymanager.position!")
　　Me.SelectedNode = FindNodeByValue(GetValue(cm.Position), Me.Nodes)
　End If
　If AllowEdit Then
　　If Me.SelectedNode Is Nothing AndAlso cm.Position = cm.Count - 1 Then
　　　'当新增记录时，新增树结点
　　　If CType(cm.Current, DataRowView).IsNew Then
　　　　Me.SelectedNode = AddNode(cm.Position)
　　　　Exit Sub
　　　End If
　　End If
　　If Not oldNode Is Nothing Then
　　　If CType(oldNode, myTreeNode).Value = GetValue(oldPos) Then
　　　　'更新老结点
　　　　oldNode.Text = GetDisplay(oldPos)
　　　Else
　　　End If
　　End If
　End If
End Sub