Design Pattern's Research And Application In The Web System On J2EE

With rapid development of the network technology, more requirements are increasing inthe web application, Web Application System is more and more complex because of widerange of application. Extant Web Application System has not been able to satisfy the heavydemand of enterprise application for its shortcomings such as tight coupling, low reusabilityand low maintainability. Recent years the design pattern technology has been developingquickly, the application of design pattern enables the developer to reuse the successful designresults conveniently, it is provided with the possibility of more widely modifying and reuseon a higher level, and it is the effective way to solve nonfunctional problems in webapplication.Firstly, the thesis analyses the development and present situation of web systemdevelopment. Base on J2EE technique to develop web applications, the basic theories ofdesign pattern are discusses and how to select right design pattern is analyzed base on actualinstance to improve development efficiency, the MVC pattern basic principle is researched.On the basis of traditional system process, design pattern is applied to system developmentprocess, introduces design patterns to instruct design and development. Under the method,through the analyzing the characteristics and traditional models, a web application systemmodel is constructed based on design pattern upon practice, this model includes three layer:data access layer, business logical layer and presentation layer. A general data layercomponent is designed upon the combination of simply factory and facade pattern to solve theproblem of different types data sources and the unified interface of data access; in order torealize low-coupling and high-aggregation function between different layers, we designbusiness logical component model with its interface Facade in detail; after that, it designspresentation layer model briefly; aiming to solve the problem of data consistency betweenbusiness logical layer and presentation layer on web application system, this paper improvesthe MVC pattern: using observer pattern to implement the data consistency between viewerand specific model. This method can realize renewing of presentation layer through callingthe function of data access layer when the model data are changed, decreases the load ofdatabase system and amount of data flow in network, and improves the quality of network.Finally, applying these design patterns in the design and development of network OA(Office Automation) system, this paper uses state pattern to design the document system,makes more accurate explanation about the use of design pattern in web application, resolves some problems in the system such as design of software architecture, accessing to databaseand data interface, and it greatly improves the system performance.