Authenticating AD server user using DOD issued CAC

Question

I have to authenticate an user residing in AD server using the DOD issued CAC(without using any username or password) using java. I will have CAC middle ware ActiveClient installed in the machine which is required to access the content(user certificates) on CAC. On some research i found that Kerberos + PKINIT should be used. I am not sure about where to start. Can someone help me out?