vb.net中怎么检测一个已知的文件是否已经被打开或者被其他应用程序调用

Dim filename As String = "02.xls"
        Dim ps() As Process = Process.GetProcesses
        Dim p As Process
        For i = 0 To ps.Length - 1
            p = ps(i)

            If p.MainWindowTitle.Contains(filename) Then
                MsgBox("文件打开")
            End If

        Next