gistfile1.java

    @PersistenceContext(unitName = "nomeDaUnidade")
    private EntityManager em;
    @Resource
    private javax.transaction.UserTransaction utx;

    public void persist(Object object) {
        try {
            utx.begin();
            em.persist(object);
            utx.commit();
        } catch (Exception e) {
            Logger.getLogger(getClass().getName()).log(Level.SEVERE, "exception caught", e);
            throw new RuntimeException(e);
        }
    }