关于hibernate使用的一个小疑点

        public class Topic {    private int tpid;    private String tptitle;    private User user;    private String tpcontent;    private Date tptime;    private Board board;    private int tpreplynum;    private String tpstop;    private String tpico;        .......

                        s = HibernateUtil.getSession();            String hql = "from Topic as topic where topic.board.bdid=:n ";// from Object            Query query = s.createQuery(hql);            query.setInteger("n", tpboardid);            topiclist = query.list();// executQuery();                        ActionContext ac = ActionContext.getContext();                        ac.put("topiclist", topiclist);