Research & Realization Of Data Persistence Layer In The J2EE Framework

In this paper, it researches and realizes the mapping theory between the object and relational database, and manages the persistent objects. Based on the MVC design model and the programming distributed application system, the data about reading and writing in the business logic layer is very important topic. It takes out the data persistent layer by coupling and OOD.Currently, there are many approaches to save the persistent layer in the Web Application system programming, such as tool class, Entity Bean, JDO etc, which provide the interface of CRVD operation about value object for the business programmer, which realizes data communications between the attribute of class and the table of the database by concealing the middle operation. In this paper, based on the balance of the file system and database system about storing value object, particularly analyses how to generate the database table and relations from the inheritable, assembled classes and how to design the class from the relational tables. By the conversion of the three states in the cache (transient, persistent, detached), it manages value objects in the container.Secondly, it analyses deeply how to store the XML text. With the JAXB technology supporting, data object may convert into XML by serializable and reverse operation by parse to store data object, lastly analyses how to store XML data in the database by the Data-Centric-Documents and Document-Centric-Documents.The project "Shannxi Customer Service Support System" which the author participated subject, is the background of the paper. Plenty of theoretic research, design practice and developing work have been carried out .Based on the practice, the presented framework of persistent layer has been implemented and achieved fine result.