The Research And Implementation Of Online-Exam System Based On J2EE

With the development of information technology, informationization of education is an inevitable trend. The exam as a standard of education evaluation has also been experiencing paperless and network leap. The online-exam system based on Web technology has been an important application of Internet, and there are important academic and realistic meanings to the research of this direction. The online-exam system based on J2EE that this paper introduces is a practical item that the author joined, and the system is based on technologies of J2EE and the framework based on MVC pattern is used. In this system the functions of online-exam, practice, simulation exam and exam information management are implemented.The paper puts emphasis on the two key technologies of the online-exam system: the researches of the algorithm of generating test paper and the researches of security of question and grade databases.The algorithm of generating test paper is a hard point during the implementation of the system. The author first analyzed and designed the algorithm. Base on the analysis of the traditional generating paper algorithms and the features of genetic algorithm, a generating test paper method based on improved genetic algorithm is put forward.In addition, in the researches of security of question and grade databases, through enough studying and demonstration, two measures are taken: first, based on research of encryption and digital sign, the author puts the emphasis on analyzing the problems of the authentication between receiever and sender and avoiding questions revealed, communication model of Non-Repudiation between sender and receiver is adopted, exam database's authentication between sender and receiver by using PKI is discussed and the important data is encrypted by using 3DES algorithm; Second, the author puts forward and implements the two-level management model of database transaction management and grade encryption.The research results of the two key technologies have been applied to the online-exam system, the system has been running well, and the result is good.