Convert Oracle database to Derby
Apache DdlUtils can help with some of the migration: http://db.apache.org/ddlutils/

You might also have a skim of the tools listed here: http://wiki.apache.org/db-derby/UsesOfDerby to see if any of those have features that help with migration

Derby also has some built-in tools for bulk-importing of data: http://db.apache.org/derby/docs/10.9/ref/rrefimportproc.html