Protected OverLoads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

请说明一下：
If Not (components Is Nothing) Then
     components.Dispose()
到底有什么意义啊？实现了什么？