String persistenceUnitName = "persistenceUnit";
EntityManagerFactory factory = Persistence.createEntityManagerFactory(persistenceUnitName);
this.entityManager = factory.createEntityManager();
VietnamStationDaoImpl vietnamStationDaoImpl = new VietnamStationDaoImpl();
vietnamStationDaoImpl.setEntityManager(entityManager);
this.vietnamStationDao = vietnamStationDaoImpl;
}