hibernate3 的常用操作（批量删除，批量插入，关联查询）

1 批量删除是调用sql引擎执行sql语句。批量插入有两种方式，a：自己拼接出一条sql语句 b：利用hibernate的session一级缓存，每多少条刷新缓存存入数据库

@Component
public class StudentDao extends HibernateDao<Student, Integer> {

    public void deleteByIds(List> ids) {
        String hql = "delete from Student where id in (:ids)";
        createQuery(hql).setParameterList("ids", ids).executeUpdate();
    }

    public void saveBatch(List stuList) {
        if (null != stuList && stuList.size() > 0) {
            Session session = sessionFactory.openSession();
            Transaction tx = session.beginTransaction();
            try {
                for (int i = 0; i < stuList.size(); i++) {
                    session.save(stuList.get(i));
                    if (i % 100 == 0) { // 每一百条刷新并写入数据库
                        session.flush();
                        session.clear();
                    }
                }
            } catch (HibernateException e) {
                e.printStackTrace();
            }finally{
                tx.commit();
                session.close();
            }
        }
    }
}
//批量查询，当然hibernate也提供了使用某一个属性查询出集合
    String hql = "from Goods  where  merchandiseId in (:ids)";
    List goodsList = goodsDao.createQuery(hql).setParameterList("ids", idList).list();

2 批量插入采用sql时如下：

public void setMappingGoods(Integer merchandiseId,List ids) {
        StringBuilder sb = new StringBuilder();
        sb.append("insert into mapping_goods(kid,oid) values ");
        for(Integer id:ids){
            sb.append("("+merchandiseId+","+id+")"+",");
        }
        goodsmapDao.getSession().createSQLQuery(sb.substring(0, sb.length()-1)).executeUpdate();
    }

3 hql 关联查询:当没有在实体中设置关联关系，而是自己建立的中间表时，可以用hql关联查询数据。

    public List getMappingGoods(String kuuid) {
        if(StringUtils.empty(kuuid)){
            return new ArrayList();
        }
        String hql = " from Goods g where  g.merchandiseUuid!=? and ( (g.merchandiseUuid in (select mp.kuuid from Goodsmap mp where mp.kuuid=? or mp.ouuid=?)) or (g.merchandiseUuid in (select mp.ouuid from Goodsmap mp where mp.kuuid=? or mp.ouuid=?)))";
        return goodsDao.find(hql,kuuid, kuuid,kuuid, kuuid,kuuid);
    }