The Persistence Layer Technology. J2ee Framework To Integrate Design And Implementation Of The Hibernate Ejb Architecture

With the widely use of J2EE technology in enterprise application and the deepresearch of J2EE, the controversy about it is more and more fury. The controversy ofJ2EE focused on its core technology EJB, especially Entity Bean. Entity Bean iscriticized because it is heavyweight, it is difined in "one-to-one"correspondence tothe tables of the relational model, it dosen't support polymorphic associations andqueries, it isn't portable in vendor-specific, etc. Then some other ORM products arecoming on.ORM means object-relational mapping. It is an important technique inobject-oriented designing. Hibernate is an ORM tool for java environment. It managesthe mapping from java classes to database tables and the operation of persistentobjects. Hibernate's ORM can mapping one object to many tables, can mappingseveral types of associations and class inheritance. Hibernate query language realizedpolymorphic association query and dynamic query.This paper mainly researched persistence technology of J2EE, that is how tomapping java objects to relational database and manage persistent objects, thendesigned an EJB structure consists of business logic layer and persistent layer. In thispaper, the author first introduced J2EE framework and its related technology. Then,ORM is represented and several kinds of java ORM techniques are compared. Next,the new ORM tool Hibernate is described in detail. Finnally, based on the researchproject E-learning system, the author designed a new EJB structure with Hibernate,and realized the design in sub-system CourseSelect of E-learning system.