如何在Excel中一次性保护文件夹中的所有工作簿？

Sub ProtectAll()
    Dim xWorkBooks As Workbook
    Dim xExitFile As String
    Dim xPassWord As Variant
    Dim xStrPath As String
    Dim xFileDialog As FileDialog
    Dim xFile As String
    On Error Resume Next
    Set xFileDialog = Application.FileDialog(msoFileDialogFolderPicker)
    xFileDialog.AllowMultiSelect = False
    xFileDialog.Title = "Select a folder [Kutools for Excel]"
    If xFileDialog.Show = -1 Then
        xStrPath = xFileDialog.SelectedItems(1)
    End If
    If xStrPath = "" Then
        Exit Sub
    Else
        xStrPath = xStrPath + "\"
    End If
    xPassWord = Application.InputBox("Enter password", "Kutools for Excel", , , , , , 2)
    If (xPassWord = False) Or (xPassWord = "") Then
        MsgBox "Password cannot be blank!", vbInformation, "Kutools for Excel"
        Exit Sub
    End If
    xFile = "*.xls"
    xExitFile = Dir(xStrPath & xFile)
    On Error Resume Next
    Application.ScreenUpdating = False
    Do While xExitFile <> ""
        Set xWorkBooks = Workbooks.Open(xStrPath & xExitFile)
        Application.DisplayAlerts = False
        xWorkBooks.SaveAs Filename:=xWorkBooks.FullName, Password:=xPassWord
        Application.DisplayAlerts = True
        Workbooks(xExitFile).Close False
        Set xWorkBooks = Nothing
        xExitFile = Dir
    Loop
    Application.ScreenUpdating = True
    MsgBox "Successfully protect!", vbInformation, "Kutools for Excel"
End Sub