持久层实现研究

Research on Persistence Layer Model

开发一个同时使用面向对象技术和关系型数据库技术的项目是一件困难的事情。为了解决面向对象技术和非面向对象技术之间存在阻抗不匹配问题,在企业应用开发过程中需要使用持久层来减少不匹配带来的影响。持久层是根据分层思想的指导,通过建立逻辑门户,采取一定的对象-关系映射策略,隐藏所有数据库访问代码细节,向开发人员提供的透明的对象持久化机制。在对现今流行的持久层设计技术、DAO模式和CMP模式的实现,进行深入分析的基础上,讨论了一个良好的持久层所应具备的功能,提出了一个持久层实现模型。

Designing software to connect an object- oriented business system with a relational database is a tedious task. In order to resolve inharmonious problem of impedance between object -oriented business system and non- object - oriented business system, the persistence layer is used to reduce effects that inharmonious impedance brings about while enterprises apply and exploitate the system. The persistence layer is a transparent object - enduring - mechanism system provided to the persons who develop according to the directions of the thoughts wlth layers,by building up a logic door, by adopting the certain object - relation mapping tactics to conceal all code details which all data bases access. With the analysis of popular technology,the realization of DAO pattern and CMP pattern,discusses the necessary function of a well-designed persistence layer. At last,deseribe a realization rrolel of persistence layer.