Question

I am using Java persistance and there EntityManager class and have it assigned to storage a class object that shall be written to the database. My problem is that I want to write to different databases using the same storage class. My solution to that was to write a StorageManagerfactory that has a Map holding all EntityManagers. The solution looked good until I looked at the databases and realized that all information (undepending of the Map, which gets the correct value) was written to the same database (one of the initialised in the Map).

So my question is:
Can I write to different databases using JPA that is using the same storage class (the class holding the structure of my database)?

Thanks

Answer 1

My solution to that was to write a StorageManagerfactory that has a Map holding all EntityManagers

I don’t think a Map of EntityManager is a good idea.

However, it should be possible to use
Persistence.createEntityManagerFactory(String, Map) to create N EntityManagerFactory pointing to N databases (the mentioned factory method allows to pass additional properties that override values that may have been configured elsewhere, for example a connection url) and to these EntityManagerFactory in a Map.

Then, simply get the “right” EntityManagerFactory from the Map (use the whatever key you want) and get an EntityManager.