一个可动态扩充的数据访问对象模式  

New DAO pattern with dynamic extensibility

作　　者：方铖[1] 曾平[2] 

机构地区：[1]武汉工业学院计算机与信息工程系,武汉430023 [2]武汉大学计算机学院,武汉430072

出　　处：《计算机应用》2007年第10期2498-2500,共3页journal of Computer Applications

摘　　要：当前已有的数据访问对象(DAO)模式普遍存在诸多不足之处,例如与业务对象的耦合度较大,不能实现软件系统的动态扩充,实现代码重复,系统维护难度较大等。针对这些问题,借鉴数据绑定的有关思想,引入元数据、元模型的概念,利用XML语言的独立性,提出了一个独立性更强、可动态扩充的数据访问对象模式,并结合具体应用实例说明了该模式的使用过程。该模式的创新之处在于如果需要增加业务对象,只需要修改映射文件,不必改动DAOFactory类的任何代码;而且由于该模式用一个DAO实现类完成所有业务对象的数据访问,如果需要修改某个SQL语法,只需要修改这个DAO实现类,不必逐一修改各业务对象类对应的DAO实现类。Currently the existing Data Access Object （DAO） patterns have several limitations. First, the interface of the patterns and business objects is tightly-coupled, which seriously affects the dynamic extensibility of software systems. Second, the patterns have duplicated implementation codes, which adds to the difficulty of system maintenance. To solve these problems, a new DAO pattern with stronger independency and dynamic extensibility was proposed in the paper based on the concepts of data binding, meta data and meta model. Finally, an example was given to illustrate the using process of the new DAO pattern. The greatest advantages of the new DAO pattern are as follows. If any business object is needed to add to the system, we don＇t have to modify any codes of the class DAOFactory. All that we need to do is to modify the mapping file. Furthermore, because we have only one DAO implementation class to accomplish all the data access to business objects, if some SQL statements are needed to be modified, all we need to do is to modify the DAO implementation class but not modify any business objects.

关 键 词：模式 数据访问对象 数据绑定 元模型 

分 类 号：TP311.5[自动化与计算机技术—计算机软件与理论]