My Chihuahua hates everyone

Question
I have researched and looked up a lot of information on Chihuahuas and I know that they are "one person" dogs, however My Chihuahua (long haired, apple head) hates everyone but me and I was wondering how I can at least get him to if not like other people but tolerate others. I'm not sure if it is a training issue or behavioral one, but he hides and barks at anyone who comes near him or me. Should I try to train him or is it something you can't train? I'm not about to get rid of my dog over this but it does get a bit annoying.

Thank you!
Megan

Answer
Well one thing you can try is to have a friend come over,and give him small treats to show him that people are not going to hurt him,even if at first the friend has to just toss the treats at him-then slowly let the dog take the treats from the friend's hand,and you can do this with a few friends but just one at a time

This usually works pretty well-but if it doesn't it doesn't hurt to talk to a trainer as they might have something else that will work,and it still might not hurt to get him into classes,as it often brings dogs out of there shell