Component Geographic Information System Design, Practice And Reconstruction

In recent years, The development of GIS is tend to Components, Network and Virtuality. As a new development pattern that based on components development has unparalleled prepondance in raising the ability of reuseness and maintainability. Many people have pain a lot of attention to it and many GIS software have been produced based on the component.This paper take "The Virtual Geographical Environment Creating System" as an example, expatiating we how to design, how to practice and how to refactoring the component object model geography information system(ComGIS). The purpose of designing, practicing and refactoring ComGIS is that to make use of The Orient Object technology to design the system's construction layout, make use of The Design Pattern technology to increase the system' design in reuseness and maintainability, make use of The COM technology to workout the system's modules, make use of The Refactoring technology to improve the existing code. So this paper make some reserches on the subjects of design pattern, component and refactoring with "The Virtual Geographical Environment Creating System".1. Design Pattern is indispensable and important for orient object design. Design pattern displayed how to use the basic techniques such as the object, inheritance and polymorphism. Designing Pattern can make you describe "why" to design it in this way, but not record your design result simply, in that case the applicability, effect and realization can help us make any necessary decision of design. In the process of designing the component object model geography information system, we adopt many a mature design patterns, in aid of increasing the reuseness and the maintainability of the system.2. The reuseness of software not only express on the source code degree, but also express on the binary code degree. COM is the best method to realize the reuseness of binary code, and it is also the base of the component object model geography information system. So this paper proceeds with the introducing of COM's basic concept, end with realizing two dimension electron map display components and doing perfect self-consistent in establishing ComGIS.3. With the appearance of the refactoring theory, a great idea comes to our mind and in a large extent helps us for cleaning up the logic of the programme and increasing the reuseness of the code. There are some prodigious differences between the refactoring theory and the orther's theory, therefore using the refactoring theory in ComGIS has its own particularity. Refactoring is an important part of the ComGIS design, it has optimized the old system, and it has optimized the old system day after day. In according to the refactoring theory, this paper sums up some key proceedings must be emphasized in the refactoring system, and explores the application on the refactoring in the ComGIS.