Best two defences against bear attack are: 1) bear smarts, that is, don't do stupid things that attract, enrage or frighten bears, and 2) situation awareness in woods, just like anywhere else.

Bumble around in woods, paying no attention to what is around you, messing with most any bear, especially one with cubs, enticing bear with food, surprizing bear in a threatening manner, seeming to want their food, etc., etc.

Mostly bears will avoid humans, given any reasonable option, especially black bears. Bears are most likely far more aware of your presence than you are of theirs, often without you ever knowing they were there. After a lifetime of encountering black bears in woods, sometimes at very close range, I have never been threatened or felt threatened. Generally I was not carrying any gun at all.

Niklas