插件式GIS應用框架的實現(xiàn)與應用

1、2012年8月第10卷第4期地理空間信息GEOSPATIALINFORMATIONAug.,2012Vol.10,No.4 插件式GIS 應用框架的實現(xiàn)與應用聞平,王媛,王沖(中國水電顧問集團昆明勘測設計研究院,云南昆明650051摘要:插件式GIS 應用框架是一種可擴展、可復用的GIS 體系架構,可顯著降低GIS 軟件開發(fā)和維護的成本,增強GIS軟件應用的靈活性,還能有效解決GIS 應用需求多變的問題。通過對插件式框架的結構、插件技術等方面的研究,并結合實例,實現(xiàn)了一個基于.NET 平臺插件式GIS 應用框架。關鍵詞:插件式;GIS 應用框架;實現(xiàn);應用中圖分類號:P208文獻標志碼:B文章

2、編號:1672-4623(201204-0118-02 收稿日期:2011-07-14GIS 軟件經(jīng)過幾十年的發(fā)展,已經(jīng)從最初的空間數(shù)據(jù)存儲和顯示的簡單應用轉換為高級地理統(tǒng)計、空間分析和地理服務等方面的應用,并且GIS 的應用領域也越來越廣泛,GIS 應用的方向和工程的復雜度也不斷增大。針對我院多部門之間共同開展的GIS 技術應用與研究,不同的部門有不同的需求,業(yè)務需求變化多端,如果繼續(xù)按照以往的軟件開發(fā)程序來實施,每個項目從頭做起,不同項目的復用部分也僅僅是停留在代碼的簡單復制與粘貼上面,這樣的技術與方法伸縮性較差,不能滿足軟件的擴展與可復用的需求,不能充分發(fā)揮多部門、多人之間的協(xié)作關系。為

3、改變上述情況以適應不斷衍生的業(yè)務需求,GIS 軟件需要擁有結構清晰簡潔、支持復用、可擴展性強和易于維護等高性能的架構。插件式GIS 應用框架是解決上述問題的比較好的技術途徑,本文基于.NET 平臺設計了面向應用型的插件式GIS 應用框架,并對其實現(xiàn)原理進行了深入研究,將研究成果應用于實際,取得了較好的效果。1插件技術1.1基本概念插件是按照預定接口實現(xiàn)的軟件功能構件。應用程序可在“運行時”動態(tài)加載插件并執(zhí)行其功能。插件技術是一種提高軟件復用性和可擴展性的有效方法。插件技術使應用軟件具有很好伸縮性,在軟件領域已有較廣泛的應用。1.2插件的實現(xiàn)技術插件的實現(xiàn)一般有3種技術:基于動態(tài)鏈接庫DLL 的

4、插件、基于組件對象模型COM 的插件和基于.NET 反射技術的插件。動態(tài)鏈接庫是具有某種功能的一種軟件模塊,動態(tài)鏈接庫文件本身并不能獨立運行,但它能夠被其他程序調用實現(xiàn),基于這種特性,使用動態(tài)鏈接庫也能產(chǎn)生插件對象。組件對象模型COM 是一種組件二進制級別的交互標準,它以COM 接口作為不同組件之間通信的通道,只要實現(xiàn)了COM 標準,使用任何一種支持COM 語言編寫的組件都能夠互相調用。在.NET Framework 中,使用.NET 的反射機制和接口技術,也能夠產(chǎn)生插件。.NET 平臺動態(tài)加載一個插件程序集后,可以通過反射機制,獲得程序集中的類型信息,如果類型信息滿足主程序的要求,主程序將使

5、用對象動態(tài)生成技術在內存中根據(jù)類型定義產(chǎn)生一個插件對象實例并加載到插件池中。本文后面所提到的插件的開發(fā)就是基于.NET 反射技術實現(xiàn)的。2插件式GIS 應用框架結構本文所述的插件式GIS 應用框架主要包括4個組成部分,如圖1所示。圖1插件式GIS 應用框架結構圖1主界面程序:該程序是以EXE 可執(zhí)行文件的形式存在,主要負責生成按鈕、工具、工具條和菜單等界面UI 對象,并負責將這些對象事件進行委托關聯(lián)。2插件引擎:提取插件程序集中包含的插件類型信息并負責將其生成相應的插件對象。3通信契約:主程序與插件之間相互認可的一種標準,以接口的形式存在,即只有實現(xiàn)了規(guī)定接口的類型對象才能被插件引擎認可為插件

6、。第10卷第4期1194插件:插件式框架具體功能的實現(xiàn),插件式框架模型將一個程序的功能劃分為相對獨立的模塊,每一個模塊就以一個單獨的插件形式存在。3插件式GIS 應用框架的設計3.1實現(xiàn)的接口本文所述的插件式GIS 應用框架主要實現(xiàn)了以下7個接口:IApplication 接口、IPlugin 接口、ICommand 接口、ITool 接口、IToolbarDef 接口、IMenuDef 接口和IDockableWindowDef 接口,其接口關系如圖2所示。 圖2接口關系圖3.2插件的動態(tài)加載本系統(tǒng)將插件統(tǒng)一放在一個文件夾(plugin 中,在主程序啟動時去查找該文件夾并創(chuàng)建可用的插件對象。

7、當用戶需要增加新的功能時,只需要將符合接口的新程序集放在plugin 文件夾中,重新啟動主程序即可完成功能的添加。同理,當用戶需要刪減一個功能時,只需要將實現(xiàn)該功能的程序集移除plugin 文件夾,重新啟動主程序即可完成功能的刪減。本框架中插件的動態(tài)加載使用了.NET 的反射機制,它能根據(jù)一個插件類型的描述信息產(chǎn)生插件對象。插件的動態(tài)加載過程如下:1使用一個靜態(tài)方法探測啟動路徑下的plugin 文件夾是否存在,如果不存在,將自動新建一個plugin 文件夾避免出現(xiàn)異常:if (!Directory.Exists (pluginFolder 不存在,系統(tǒng)自動建立了一個!"如果插件文件夾

8、存在,將尋找該文件夾中所有的DLL 文件并返回一個包含了文件路徑的字符串數(shù)組。2系統(tǒng)遍歷文件路徑數(shù)組,從中得到每一個程序集文件的絕對路徑,然后將其動態(tài)加載。3系統(tǒng)識別類型的每一個接口,如果該類型的某個接口完整名為ICommand 、ITool 、IToolbarDef 、IMenuDef 或IDockableWindowDef 中的一種,系統(tǒng)將認定該類型是一個有效的插件類型并根據(jù)該類型名產(chǎn)生一個實例對象。3.3插件的調用針對不同的插件,插件管理器獲取插件后,主程序根據(jù)插件信息生成并調用相應的插件,在主程序的系統(tǒng)界面上生成相應的菜單和工具欄,比如ICommand 表現(xiàn)為命令按鈕,ITool 表現(xiàn)

9、為工具按鈕,IMenuDef 表現(xiàn)為菜單欄,IToolbarDef 表現(xiàn)為工具條,后兩者均為ICommand 命令按鈕和ITool 工具按鈕的?？繉ο蟆?應用實例本文以.NET 平臺為開發(fā)環(huán)境,通過C#、AcrGIS Engine 9.3組件和Skyline Globe 組件完整地實現(xiàn)了一個插件式GIS 應用框架,系統(tǒng)主界面如圖3所示。圖3系統(tǒng)主界面5結語本文從系統(tǒng)框架、接口實現(xiàn)和加載等方面討論了插件式GIS 應用框架的實現(xiàn)過程,并結合實踐,搭建了一個完整的插件式GIS 應用框架。只要定義好了接口規(guī)范,后期便可以利用插件對系統(tǒng)的功能進行很好地擴展,減少重復工作,能在很大程度上提高工作效率,降低

10、開發(fā)成本和后期維護成本。參考文獻1陳方明,陳奇.基于插件思想的可重用軟件設計與實現(xiàn)J .計算機工程與設計,2005,26(1:172-1732蔣波濤.插件式GIS 應用框架的設計與實現(xiàn)M .北京:電子工業(yè)出版社,20083高慧萍,呂俊.插件式開發(fā)技術研究與實現(xiàn)J .計算機工程與設計,2009,30(16:3805-38074張毅,李國卿,趙軍喜,等.插件式GIS 應用框架關鍵技術研究J .測繪科學技術學報,2010,27(4:298-3015江麗鈞,談曉珊,孫毅中.基于插件的城市規(guī)劃信息系統(tǒng)的研究J .現(xiàn)代測繪,2010,33(1:8-106盧學鶴,余光輝,溫小榮,等.基于插件技術的森林資源G

11、IS 的設計與實現(xiàn)J .南京林業(yè)大學學報:自然科學版,2009,33(1:127-1307楊世琦,徐永近,高陽華.基于插件技術的測土施肥決策系統(tǒng)設計J .西南師范大學學報:自然科學版,2010,35(1:158-163第一作者簡介:聞平,碩士,工程師,主要從事測繪新技術開發(fā)及3S 技術應用工作。聞平等:插件式GIS 應用框架的實現(xiàn)與應用地理空間信息GEOSPATIAL INFORMATIONgistics vehicle dispatch system can help dynamic scheduling of ve-hicles effectively,besides it could c

12、ommand and control the vehicle on the way of delivery and monitor its state in time.Key words GPS,GIS,GPRS,intelligent logistics,scheduling sys-tem(Page:92 Design on the Mine Monitoring and Control System Based on 3DGIS by LU Shidong Abstract This paper introduced the necessity to develop mine moni-

13、toring and control system based on3DGIS,and described the detail of system structure and how to build the mine3D model,designed the functions of the system software.Key words3D,GIS,mine monitoring and control,system(Page:95 Realization of the Web Application of Thematic Data3D Terrain Visualization

14、by MENG Lei Abstract With the development of GIS and Web technology,the Web applications of various thematic3D visualizations are initiated nat-urally.Combining thematic data3D terrain visualization technology with NewMap,the huge thematic3D data can rapidly browse in Web explorer.Key words thematic

15、 data,3D terrain visualization,Web,NewMap(Page:98 Application of Modern Remote Sensing Techniques in Land Law Enforcement Work by SUN Jiefang Abstract This paper described the application of modern Remote Sensing techniques in land and resources law enforcement work,car-ried out a detailed descripti

16、on and analysis of the use of process tech-nology roadmap.Keywords Remote Sensing technology,law enforcement and super-vision,land and resources,RapidEye(Page:100 Design and Development of Tianjin Urban Service Hotline GIS System by LIU Yang Abstract Urban public facilities management service is the

17、 focus of government departments and public and it related to everyone's life. Urban service hotline system unifies different urban management ser-vices into a hotline voice platform,builds Tianjin service hotline of covering the whole city construction management.This article de-scribed Tianjin

18、 urban service hotline GIS system data structure,di-scussed the system function design in detail,and analyzed the techni-cal features of the system.Key words C/S architecture,ArcEngine,COM,ComGIS(Page:102 Rapid Building up and Application of Software Templates Based on COM-GIS by ZHUO Yun Abstract F

19、or GIS platform,this paper discussed the compiling and in-tegration of common basic function of a user's custom template in the Microsoft Visual Studio platform.Making it easy for integrating of C/S and B/S system's architectures,according to the needs of the project, it quickly extracted th

20、e corresponding function of the underlying functi-onality,and completed integration of basic function.The key is open-ness and compatibility of the basis of the common basic function, which has a significant impact on quickly building the project and the processing of project core function.Key words

21、 GIS re-development,software templates,rapid building platform(Page:105 Development and Application of Digital Orthophoto Topographic Map by TAN Yaohua Abstract There is variety of composite products in the basic geogra-phic information of digital products.Digital orthophoto topographic map is widel

22、y used as a product model.It is developed by the digital ortho-photo map and other relevant data,or integrated with the thematic in-formation data.Combined with the working practice,the digital ortho-photo topographic map and its application prospects were analyzed and discussed in this paper.Key wo

23、rds digital orthophoto topographic map,DOM,DLG,data ac-quisition(Page:107Methods and Skills of Quickly Entering Database for Digital Top-ographic Map in ArcGIS by GOU Haoyuan Abstract Combining with entering database for digital topographic map of torch development zones in Zhongshan City,because of

24、 the ef-fective methods and skills in the data transformation,editing and qual-ity inspection,this paper realized the quickly entering databases for digital topographic map in ArcGIS on the premise of ensuring quality. Key words digital topographic map,ArcGIS,data loading,data trans-formation,method

25、s and skills(Page:110Research on the Distribution and Target for Frame Digital Aerial Photo Control Points by ZHANG Huijun Abstract This paper emphasized on the presentation of the setting and selecting photo-control points in the photo-control point measure-ment.We draw some conclusions that the ai

26、r route network accuracy estimation formula is applicable,and the number of photo control point of the digital aerial camera should be more than the optical aerial cam-era's.In addition,in some certain conditions,it is feasible to set control points crossing the air routes,and the mapping precis

27、ion should be considered when selecting control points,but not according to the exis-ting specifications.Key words frame digital aerial camera,photo-control point,setting point,selecting point(Page:112Application of GIS in Science and Technology Serviceby LU Nana Abstract Science and technology info

28、rmation service in promoting social development plays an important role.This paper brought in GIS technology and discussed the function of it in science and technology services.Based on the detailed analysis of the disadvantages of tradi-tional science and technology services,this paper designed the

29、 ser-vice framework and its function,provided a new method for inquiry,dis-play,conversion and decision support of science and technology ser-vices.Key words GIS,science and technology service,decision support(Page:115 Implementation and Application of GIS Application Framework Based on Plug-in Technology by WEN Ping Abstract GIS application framework based on plug-in technology is a kind of extendable and reusable software architecture for GIS.It can not only reduce the cost of GIS development and maintenance,but also enhance the flexibility of GIS software.It can also solve the prob-