Creates or returns current EntityManager with EntityTransaction started. - Java javax.persistence

Java examples for javax.persistence:EntityManager

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Description

Creates or returns current EntityManager with EntityTransaction started.

Demo Code


import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.EntityTransaction;
import javax.persistence.Persistence;

public class Main{
    private static EntityManagerFactory entityManagerFactory;
    private static EntityManager entityManager;
    /**/*  ww w  . java  2  s. c  o m*/
     * Creates or returns current {@link EntityManager} with {@link EntityTransaction} started.
     * @return Current {@link EntityManager}.
     */
    public static EntityManager currentEntityManager() {
        if (entityManager == null) {
            entityManager = entityManagerFactory(persistenceUnitName)
                    .createEntityManager();
            EntityTransaction transaction = entityManager.getTransaction();
            transaction.begin();
        }
        return entityManager;
    }
    /**
     * Creates or returns current {@link EntityManagerFactory}.
     * @param persistenceUnitName Persistence unit name form persistence.xml.
     * @return Current {@link EntityManagerFactory}.
     */
    public static EntityManagerFactory entityManagerFactory(
            String persistenceUnitName) {
        if (entityManagerFactory == null) {
            JPAHelper.persistenceUnitName = persistenceUnitName;
            entityManagerFactory = Persistence
                    .createEntityManagerFactory(JPAHelper.persistenceUnitName);
        }
        return entityManagerFactory;
    }
}

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