What's the best way to use the adapter pattern in EJBs?

I have the following situation:

A business service EJB is providing the business logic for my application front-end. Below that layer I have up to tree different storage systems (Fileystem, SQL, Hadoop). I want to implement something like an adapter pattern to give the application front-end the possibility to choose one of these storage systems during the deployment phase.

How can I do this? Is the configuration via the ejb-jar.xml the only way or is there another more elegant solution with annotations possible? Later one maybe have the problem of tightly coupling one of the storage adapters to the application code.