The best way to deal with rejections is by realizing that everybody is fighting his/her own battles, and everyone responds in a way that is programmed by their own past, including everything they learned and experienced in that past.
That means, that you are seeing someone else's behaviour as a rejection towards yourself, because of your past, because of what you've learned and experienced.
This means, that if you work on yourself, on your self confidence, and on your self-love, you will feel less rejections, but you will simply witness someones behaviour, and see that it is just that. Someones behaviour.