I have found this article to be a good summary of knife laws of California (and San Francisco), even though the guy is not a laywer:
http://zknives.com/knives/articles/law/caknifelaws.shtml

If you read that article and use common sense, you'll sail through California unnoticed. It's unrealistic to worry yourself constantly about the ordinances of every little city of California. You can let yourself get paranoid to the point you don't want to wear metal belt buckles.

Side note, I have been carrying a folding knife daily for decades without incident in California, including San Francisco. I'm not saying that makes me an expert, but I have had to think about this issue within a multitude of real world situations.