Finding the current persistence unit for the current EntityManagerFactory

Question

I noticed that calling createEntityManagerFactory(null) will use the default Persistence Unit (PU) in the configuration file. Sometimes the classpaths get real

Answer 1

The problem with Jan's answer is this:

Session s=(Session)em.getDelegate();

Following J2EE api, EntityManager.getDelegate() method : Return the underlying provider object for the EntityManager, if available. The result of this method is implementation specific. The unwrap method is to be preferred for new applications.

Due to the fact that the returned object is implementation specific it may vary so there's no reliable object or attribute from which take persistence unit's name.

I propose another easy way to get. It's as easy as add to the persistence.xml's persistence-units one custom property with it's name as the following example:

    DATASOURCE
    com.package.EntityClass
    
        
    
  

and in your java code:

Map propertiesMap = entityManagerInstance.getProperties();

String persistenceUnitName = (String)propertiesMap.get("PERSISTENCE_UNIT_NAME");

EntityManager's getProperties() method is a reliable method and not vendor specific so if you set you custom property with the name of your persistence-unit at your persistence.xml you will be able to recover it later in your java code easily.