It looks like there’s already BSD-specific patches for OpenJDK according to commenter Samh; anyone want to see how well these would work for DragonFly?
Also, does someone want to work on interrupt routing for DragonFly? It’s tough and necessary work, but there are enough people that need it that there’s a potential bounty of $400 or more.
Landon Fuller posted some instructions for building OpenJDK on FreeBSD and Mac OSX a while back[1]. The big hurdle is bootstrapping the build process with another JDK, the FreeBSD build uses the java/diablo-jdk16 port. Jikes could possibly be used for compiling, but I think it then requires actually running the code, GCJ is generally not a good substitute. It could possibly be bootstrapped in some emulation mode, which is if I remember correctly how the OpenBSD port used to work. It also requires Mecurial, which I’ve had problems installing on DragonFly, but I’m assuming others have not. With a few tweaks this might work, however I’m not very familiar with DragonFly yet, so I might need a few pointers as to the right way to go about things.
[1]http://mail.openjdk.java.net/pipermail/bsd-port-dev/2008-August/000006.html