Play2 How to manage the transaction from the service layer instead of action layer?

Question

I am using Play2.1.1 Java with JPA2.0 with hibernate implementation.

to control the transaction by code instead of using @transactional like below is the normal JPA

Answer 1

something like this:

public static User getUserByIdentity(final AuthUserIdentity identity) {
    try {
        return JPA.withTransaction(new play.libs.F.Function0<User>() {
            public User apply() {       
                return User.findByAuthUserIdentity(identity);
            }
        });
    } catch (Throwable t) {
        throw new RuntimeException(t);
    }       
}

Answer 2

After some time research, I write a method JPAUtil referring to JPA provided by Play which can use normally to control the transaction manually from the service layer actually everywhere.

public class JPAUtil {

    static ThreadLocal<EntityManager> currentEntityManager = new ThreadLocal<EntityManager>();

    /**
     * Get the EntityManager for specified persistence unit for this thread.
     */
    public static EntityManager em(String key) {
        Application app = Play.application();
        if (app == null) {
            throw new RuntimeException("No application running");
        }

        JPAPlugin jpaPlugin = app.plugin(JPAPlugin.class);
        if (jpaPlugin == null) {
            throw new RuntimeException("No JPA EntityManagerFactory configured for name [" + key + "]");
        }

        EntityManager em = jpaPlugin.em(key);
        if (em == null) {
            throw new RuntimeException("No JPA EntityManagerFactory configured for name [" + key + "]");
        }

        bindForCurrentThread(em);

        return em;
    }

    /**
     * Get the default EntityManager for this thread.
     */
    public static EntityManager em() {
        EntityManager em = currentEntityManager.get();
        if (em == null) {
            return em(Constants.DATASOURCEKEY);
        }
        return em;
    }

    /**
     * Bind an EntityManager to the current thread.
     */
    public static void bindForCurrentThread(EntityManager em) {
        currentEntityManager.set(em);
    }

    public static void closeEM() {
        EntityManager em = currentEntityManager.get();
        if (em != null) {
            em.close();
        }
        bindForCurrentThread(null);
    }

    public static void beginTransaction() {
        em().getTransaction().begin();
    }

    public static void commitTransaction() {
        em().getTransaction().commit();
    }

}