I have client written using JCIFS library. Now I need to support IPv6. But JCIFS does not support.
What direction should I take please guide me.
I don't think there are any quick fixes. (The jCIFS team apparently don't believe that many people want IPv6 support. That maybe true right now, but surely it will have to change.)
I can suggest a couple of options:
Request it; e.g. add a "request for enhancement" against jCIFS using the Samba bugzilla.
Implement it yourself. This thread might give you some ideas about how to go about it.
Approach the jCIFS team about paying someone to implement it for you.