JPACategoryService.java 文件源码

@Override
public List<Category> getAllCategories() {
    EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("pl.edu.bogdan.training.db.entity");
    EntityManager em = entityManagerFactory.createEntityManager();

    // begining of transaction
    em.getTransaction().begin();
    Query query = em.createQuery("Select c from Category c");
    return query.getResultList();
}