Observers Are Model Research And Implementation

Introduce the concept of design patterns, In Object Oriented softwaredesign , programmers pay more attention to code reuse and maintenance.Design patterns helps us to reuse the successful design experience andsystem structure more conveniently and more simply. Design pattern is afile of the experience. It is used to descript the class and the target thatcommunicate with each other in specific scene, it is a problem / solutionmethod.Design patterns is used extensivly in the medium-sized system of java,follow a certain design mode, we could make the code easy to understand ,easy to communicate , in the essay ,we analysis a kind of common designpattern------Observer pattern.Observer pattern is a commonly usedpattern, especially used in interface design.C# as one kind of advanced object oriented language , not onlyabsorbed the quintessence of a lot of languages, but also created somevery useful new characteristics. With delegate and event technology wecan realize Observer pattern . Delegate and event are the strong toolswhich realizes the flexible and strong application program, we can reducethe difficulty of the work.Analyse the application of Observer from the instance , provideobserver's traditional implementation method and give its shortcoming. Inthe instance of this essay , need to realize a real-time mapping program ,observe various kinds dates ,such as the stock price ,etc. In this mode, thestock data are observed goals, and the chart is the observer. The chart hasvery ocular visual effects, From appearance come watch, it has (roll over)curve graph, block diagram,etc.. Carry on real-time mapping we discussthese kinds of charts first.Presents a traditional implementation of observer pattern, andanalyses its defects. Finally, improves the pattern by means of delegateand event in the .NET frammework, which greatly reduces the difficultiesand errors in the development process, and enhances the flexibility ofthe system.