JPA without persistence.xml

Question

I\'m trying to get started with using Guice Persist and JPA, which recommends using configuration via persistence.xml. Coming from a native Hibernate background where confi

Answer 1

Assuming that you have a PersistenceProvider implementation (e.g. Hibernate), you can use the PersistenceProvider#createContainerEntityManagerFactory(PersistenceUnitInfo info, Map map) method to bootstrap an EntityManagerFactory without needing a persistence.xml.

However, it's annoying that you have to implement the PersistenceUnitInfo interface, so you are better off using Spring or Hibernate which both support bootstrapping JPA without a persistence.xml file:

this.nativeEntityManagerFactory = provider.createContainerEntityManagerFactory(
    this.persistenceUnitInfo, 
    getJpaPropertyMap()
);

Where the PersistenceUnitInfo is implemented by the Spring-specific MutablePersistenceUnitInfo class.

Check out this article for a nice demonstration of how you can achieve this goal with Hibernate.