I'm with @nwhite0823 when my oldest would do stuff like that we just did to her what she did it got her to stop and that includes hitting

Grab his hand look him in the eyes and give him a firm no, you can also put him down immediately..he hits..he gets put down and no longer recieves your attention (for like 30 secs to a minute). You also need to teach him the positive way to interact so after the "punishment" take his hands and gentle rub your cheek or even pat it and say something like "love mommy, you have to be gentle". It really is just a ton of consistency and making sure each reaction is the same!

umm yeah hit him back... that's whats going to happen if he hits someone else or another child. my daughter use to bite where she made a kid bleed so guess what when I bit her she has never bitten a kids again and she's now five.

You have to make sure your consistent with calling attention to him hitting. Even if no isn't working, keep doing and maybe when he got to bunch, grab his hand and tell him no again. At that age, they think it's funny until they realize moms serious. One year Olds are so spontaneous and adventurous, they'll try anything they can until they get in real trouble. I know it's hard to make a child that young understand but it's doable, just don't laugh when he does things like that, he wants a reaction from you.