as I know, there's is no special interface designed for JAVA.
But, you can find some examples of how to handle dfs - Files in other programming languages in your MIKE - installation directory:
C:\Program Files (x86)\DHI\2012\MIKE Zero\Manuals\MIKE_ZERO\FileFormats
I am not a programmer, but possibly you can use the library of the .NET - API in JAVA also.
Maybe, that helps.