My dog barks a lot. How could i train him to stop?

My dog is about 2.5 years old, Male Labrador, not very territorial at all, very affectionate, and never has problems with aggression towards anyone- even little kids, but the second he even sees his own shadow, he barks. Even if he can clearly see nothing outside, he barks. Got a new piece of furniture? What a fool you are. He's gonna bark at that until he can't anymore. Is there anyway I could teach him not to bark constantly at everything? Another note is that he hasn't been fixed yet. Could getting him fixed help with it?