.NET中为组合框添加自动查询功能

来源：云中客的专栏  http://blog.csdn.net/sxycgxj/archive/2008/01/22/2058310.aspx

在窗体中添加如下方法：

       第一个方法是AutoCompleteKeyUp，它将组合框和KeyEventArgs对象作为参数，需要在组合框的KeyUp事件中调用此方法；它全根据用户输入的内容选择最接近的内容；

       第二个方法是AutoCompleteLeave，在激活组合框的Leave事件时调用，此方法仅提取用户最终选择的内容，按照组合框中的每个匹配内容修改其大小写。

代码如下：

    Private Sub AutoCompleteKeyUp(ByVal Combo As ComboBox, ByVal e As KeyEventArgs)

        Dim strTyped As String

        Dim intFoundIndex As Integer

        Dim objFoundItem As Object

        Dim strFoundText As String

        Dim strAppendText As String

        '忽略特殊键

        Select Case e.KeyCode

            Case Keys.Back, Keys.Left, Keys.Right, Keys.Up, Keys.Down, Keys.Delete, Keys.CapsLock

                Return

        End Select

        '在查询列表中找到

        strTyped = Combo.Text

        intFoundIndex = Combo.FindString(strTyped)

        If intFoundIndex >= 0 Then

            objFoundItem = Combo.Items(intFoundIndex)

            strFoundText = Combo.GetItemText(objFoundItem)

            strAppendText = strFoundText.Substring(strTyped.Length)

            Combo.Text = strTyped & strAppendText

            Combo.SelectionStart = strTyped.Length

            Combo.SelectionLength = strAppendText.Length

        End If

    End Sub

 

    Private Sub AutoCompleteLeave(ByVal Combo As ComboBox)

        Dim intFoundIndex As Integer

        intFoundIndex = Combo.FindStringExact(Combo.Text)

        Combo.SelectedIndex = -1

        Combo.SelectedIndex = intFoundIndex

End Sub

 

    Private Sub ComboBox1_KeyUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles ComboBox1.KeyUp

        AutoCompleteKeyUp(ComboBox1, e)

    End Sub

 

    Private Sub ComboBox1_Leave(ByVal sender As Object, ByVal e As System.EventArgs) Handles ComboBox1.Leave

        AutoCompleteLeave(ComboBox1)

    End Sub