@IocBean(name="userDao")
public class UserDaoImpl implements UserDao {

@Inject
protected Dao dao;
public List<User> getAllByUserName(String username){
    List<User> userList = dao.query(User.class,Cnd.where("loginName","=",username));
    return userList;
}

}
上面这个方法进去看dao是null，请问是为什么呢