.NET中如何弹出一个选择目录的窗口

Private strFileName As String = "c:\temp\aaa.txt"
Private Sub btnSave_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnSave.Click
'Set the Save dialog properties...
With SaveFileDialog1
.DefaultExt = "txt"
.FileName = strFileName
.Filter = "Text files(*.txt)|*.txt|All files(*.*)|*.*"
.FilterIndex = 1
.InitialDirectory = "c:\temp\"
.OverwritePrompt = True 'FALSE则直接覆盖文件
.Title = "SQL server backup"

End With

'Show the save dialog and if the user clicks the Save button
If SaveFileDialog1.ShowDialog = DialogResult.OK Then
strFileName = SaveFileDialog1.FileName
Dim objWriter As StreamWriter = New StreamWriter(strFileName, False)
obj