最近实习，初接触项目，对好多的东西不是很清楚，看了下面的这篇博客对一个Web服务的实现中使用DTO及MO有了比较清楚的了解！！！

http://www.cnblogs.com/loveis715/p/4379656.html

在三层模型中，service层一般操纵的数据类型是DTO类型的

而dao层则操纵的是底层的PO类型的javabean对象。

如下所示：

public interface GroupShopDao extends GenericDao {@DAOAction(action = DAOActionType.INSERT)public int addGroupShoup(@DAOParam(value = "groupShop", type = DAOParamType.ENTITY) GroupShop obj);@DAOAction(action = DAOActionType.QUERY)public List<GroupShop> loadGroupShoupByActivityId(@DAOParam(value = "activityId", type = DAOParamType.NORMAL) Integer ActivityId);@DAOAction(action = DAOActionType.UPDATE)public int updateGroupShoupById(@DAOParam(value = "obj", type = DAOParamType.ENTITY) GroupShop obj);@DAOAction(action = DAOActionType.INSERT)public int batchInsertGroupShoup(@DAOParam(value = "list", type = DAOParamType.NORMAL) List<GroupShop> list);@DAOAction(action = DAOActionType.DELETE)public  int deleteGroupShopById(@DAOParam(value = "id",type = DAOParamType.NORMAL)Integer id);
}

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public interface GroupShopService {/*** 保存 组队商家信息* @param obj* @return 成功 or 失败*/public int addGroupShoup(GroupShopDTO obj);/**** 根据活动id 获取组队商家信息* @param ActivityId 活动id* @return 成功 or 失败*/public List<GroupShopDTO> loadGroupShoupByActivityId(Integer ActivityId );/*** 根据id修改组队商家信息* @param obj  primary key* @return success or  failure*/public int updateGroupShoupById(GroupShopDTO obj);/*** 批量添加商家信息* @param list* @param userId 用户的id* @return success or primary key*/public int batchInsertGroupShoup(List<GroupShopDTO> list ,int userId);public int deleteGroupShopById(Integer id);
}