I just posted Sexting/Texting, etc. Though I'm sure you are younger, and with my situation I probably shouldn't be giving advice BUT I guess it doesn't matter how old a man is---their behavior can be much the same. I don't know if you'll number this as one of your choices but I say:
Don't ignore him if he says "hello" or similar, but don't talk to him either. Just say "hi" and move on. Whatever you do don't approach him to say "hello". Don't attempt to converse if he tries to engage you, excuse yourself and go put on lipstick. If possible, in a group or otherwise try to position yourself with your back to him. If he enters a group or conversation in which you're involved, stand your ground. You have as much a right as he to be there. Act casual, remain neutral, don't react or respond to what he says, and move on before it just becomes the 2 of you in a "group". JMHO.