@Override
 public List<Teacher> listAll() {
   return teacherDao.listAll();
 }
 @Override
 public Teacher retrieveTeacherById(long id) {
   return teacherDao.get(id);
 }
 @Override
 @Transactional(readOnly = false)
 public void deleteTeacher(Teacher teacher) {
   teacherDao.delete(teacher);
 }
 @Override
 @Transactional(readOnly = false)
 public void newTeacher(Teacher teacher) {
   teacherDao.add(teacher);
 }