I cross the street when I'm walking my dog and see another dog approaching. This usually mitigates their response as we pose less of a threat and it also gives me extra time to gauge their reaction. It also probably helps that my dog and I completely ignore them.

If owners can't/won't get their own dogs to stop barking/lunging, I doubt there is much you can do. I would say give them as much space as possible and go another way if you see an unleashed dog.

If you do find yourself in danger, make sure you have a plan. My recommendation: do not try to ride away. Doing so will activate their instinct to give chase. Dismount your bike and place it between you and the dog. You can purchase dog deterrents online. There are loud horns as well as pepper sprays (which can be used on people as well).

Hopefully it will never come to that, but it may also help you feel more confident when riding by dogs.