Android : How to get NFC ID from Android mobile phone

I'm trying to develop application for exchange data between Android mobile to Android mobile and Android mobile to Desktop application by NFC module.

My project detail:

I use opensource for develop my Desktop application is GNFC, reference here: https://github.com/elechouse/GNFC. This application can get some unique id from mobile phone(need to un-lock mobile screen and still no SIM CARD) and then I want to use unique id to identify of user on my android application but I don't know how to write code get it.

I try to check this unique id may be EMEI number or Android id but it isn't. I guess it's ID of NFC but I don't know how to get it

Please don't suggest me use HCE because I want android application support at least android version 4.0. Thanks.