通用设计

上述常规编码方式，目录树的层级越多，代码就越复杂，下面我们提供一个通用的筛选树代码，不过有多少层，代码都一样。

设计步骤同样很简单:

1、新建一个窗口，插入一个目录树控件，将目录树的“显示复选框”属性设置为True。

2、将窗口的AfterLoad事件代码设置为：

e.Form.Controls("TreeView1").BuildTree("订单", "产品|客户|雇员")

3、将目录树的AfterCheckNode事件代码设置为：

Dim nms As String() = {"产品","客户","雇员"} \'指定生成目录树的各列
Dim qts As String() = {"\'","\'","\'"} \'指定将各列的值括起来的符号,这里都是字符型,所以都是单引号
Dim trv As WinForm.TreeView = e.Sender
Dim flt As String
Dim nd As WinForm.TreeNode
For Each nd In e.node.allNodes \'清除子节点的选中标记
    nd.Checked = False
Next
nd = e.Node.ParentNode
Do While nd IsNot Nothing \'清除父节点的选中标记
    nd.Checked = False
    nd = nd.ParentNode
Loop
For Each nd In trv.AllNodes
    If nd.Checked  Then
        Dim rts() As String = nd.FullPath.Split("\\")
        Dim val As String = ""
        For i As Integer = 0 To rts.length - 1
            If val > "" Then
                val = val & " And "
            End If
            val = val & nms(i) & " = " & qts(i) & rts(i) & qts(i)
        Next
        If flt > "" Then
            flt = flt & " Or (" & val & ")"
        Else
            flt = val
        End If
    End If
Next
Tables("订单").Filter  = flt