Our cavalier is not a barker. We trained in early what is acceptable behavior. Every time he barks, firmly state "no bark". When he stops even for a second or 2, say good boy and give him a tiny kibble treat. Divert his attention to something else.
It's worked for us well. Although...at times he loses control and cries like he's being murdered (no exaggeration). We're working on this issue now.
Cavaliers are wonderful dogs. Work with him a few times a day to encourage a bark and then tell him when to stop.
I hope you find this helpful.