LpSolve supports LP files as well as MPS files. Everything is thoroughly detailed in the API documentation (see http://lpsolve.sourceforge.net/5.5/).
You can do your job like this in java :
lp = LpSolve.readLP("model.lp", NORMAL, "test model");
LpSolve.solve(lp)
What is sad with file based approaches is that you will not be able to use warm start features. I would not suggest you to use such approach if you want to optimize successive similar problems.
Cheers