Package com.zfabrik.hibernate

Class EntityManagerUtil

java.lang.Object

com.zfabrik.hibernate.EntityManagerUtil

public class EntityManagerUtil
extends Object

Utility functions for Entity Manager provisioning.

Constructor Summary

Constructors

Constructor	Description
EntityManagerUtil()

Method Summary

Modifier and Type	Method	Description
static javax.persistence.EntityManagerFactory	createEntityManagerFactory(String persistenceUnit)	Create an EMF using the Persistence class running in a good naming environment.
static javax.persistence.EntityManagerFactory	createEntityManagerFactory(String persistenceUnit, Map<?,?> properties)	Create an EMF using the Persistence class running in a good naming environment.
static javax.persistence.EntityManager	getEntityManager(javax.transaction.TransactionManager tm, javax.persistence.EntityManagerFactory emf)	Get an entity manager given a transaction manager and an entity manager factory.
static void	releaseEntityManager(javax.persistence.EntityManagerFactory emf)	Release an entity manager factory from the current TX.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

EntityManagerUtil

public EntityManagerUtil()

Method Details

getEntityManager

public static javax.persistence.EntityManager getEntityManager(javax.transaction.TransactionManager tm,
 javax.persistence.EntityManagerFactory emf)

Get an entity manager given a transaction manager and an entity manager factory. Note, given an entity manager factory always pass the same transaction manager. The transaction manager is used to register a synchronization so that the following behavior can be implemented:

• For every invocation within the same transaction, return the same entity manager.
• Disassociate the entity manager from the transaction, when it completed.

In conjunction with Z2's built-in JTA implementation, use this method like this whenever you need an EM:

 EntityManager em = EntityManagerUtil.getEntityManager(
   IComponentsLookup.INSTANCE.lookup(
     "com.zfabrik.jta/userTransaction",
     TransactionManager.class
   ),
   this.emf
 );
 

Create the EMF at initialization time like this:

 this.emf = ThreadUtil.cleanContextExecute(
   this.getClass().getClassLoader(),
   new Callable<EntityManagerFactory>() {
     @Override
     public EntityManagerFactory call() throws Exception {
       return EntityManagerUtil.createEntityManagerFactory(PERSISTENCE_UNIT_NAME);
     }
   }
 );
 

assuming you have a META-INF/persistence.xml in your implementation that is in the same class loader scope as the code above. See the example Sample-hibernate-basic for more details.

Parameters:

tm - The transaction manager in use

emf - The entity manager factory to use when a new entity manager needs to be created

Returns:

releaseEntityManager

public static void releaseEntityManager(javax.persistence.EntityManagerFactory emf)

Release an entity manager factory from the current TX. This is happening automatically at the end of a TX.

createEntityManagerFactory

public static javax.persistence.EntityManagerFactory createEntityManagerFactory(String persistenceUnit,
 Map<?,?> properties)

Create an EMF using the Persistence class running in a good naming environment. Hibernate JNDI lookup is broken in multiple ways (see e.g. https://hibernate.atlassian.net/browse/HHH-8818) One way in which it is broken is that it asks for a name parser before a URL lookup which fails if there is no ICF on the jndi.properties defaults (or elsewhere) - which is nonsensical in the first place. So effectively, calling this method is equivalent to Persistence.createEntityManagerFactory(String, Map) calls, except of the naming context

createEntityManagerFactory

public static javax.persistence.EntityManagerFactory createEntityManagerFactory(String persistenceUnit)

Create an EMF using the Persistence class running in a good naming environment. Hibernate JNDI lookup is broken in multiple ways (see e.g. https://hibernate.atlassian.net/browse/HHH-8818) One way in which it is broken is that it asks for a name parser before a URL lookup which fails if there is no ICF on the jndi.properties defaults (or elsewhere) - which is nonsensical in the first place. So effectively, calling this method is equivalent to Persistence.createEntityManagerFactory(String, Map) calls, except of the naming context