Access Raw Contact ID of a Facebook contact from the lookup URI

I know that it's not possible for Android applications to access Facebook contact info. What I'd like to do is just to retrieve the raw contact ID of a Facebook Raw Contact based on it's lookup URI. I don't need any other info from the contact. I can obtain the lookup U开发者_如何学JAVARI if the Facebook contact is linked to a GMail or Twitter contact. I'd like to use this lookup URI to retrieve the FB contact even if the contacts get unlinked. Thanks