Copy all the content of a JDBCDataSource to another JDBCDataSource

Question

For testing reasons, I need to take a snapshot of a given database which I can access only through JDBC( I don't have command line/administrative access)

I would need to copy all its content in another data source, typically an H2SQLDB backed by a file, so that I can run isolated tests not depending on the original data source.

What is the best approach to clone a JDBC database? I didn't really find any , except using DBUnit export utils to export to XML the first database, and import in a second database.