The Research Of Implementation Method For WebGIS Based On Java Servlet And Its Performance Optimization

WebGIS is a new technology of using Web technology to expand and improve the geographic information system. It is a computer information system of compatibilizing, storing, processing, analyzing and displaying geographic information in network environment. WebGIS based on Java Servlet mode has more advantages than that based on other modes. The combination of GeoServer and OpenLayers is the best choice for achieving WebGIS based on Java Servlet model.Several WebGIS modes are compared, and the mode based on Java Servlet is analyzed and studied with GeoServer and OpenLayers. The system discussed in this paper includes a server-side and a client-side. The server-side is designed as two layers.The WFS server and the the geographic application server are created. Next, the process for transforming and importing data into database, the details of editing SLD files and the steps of creating layer group are demonstrated. For the client-side design, the common basic functions are analyzed and implemented, and advanced functions are expanded for practical needs. The basic functions include showing map, zooming out, zooming in, moving, displaying latitude and longitude and displaying scale, and the advanced functions include calculating distance, analysing and locating a place with a given name and appending labels.The server's performance bottlenecks are studied in this thesis and a variety of optimization scenarios are put forward. Besides the complementary programs, ultimate solutions to improve the performance of server-size are proposed, such as tuning the JVM's performance, establishing a cache server and improving it, storing cache pictures with tmpfs. After research, it is concluded that those methods are extremely effective. The optimization of JVM will speed up garbage collection and improve the efficiency of the GeoServer. Setting up a cache server will reduce waiting time of clients and accelerate the map swith from one format to another. The storage with tmpfs memory will cut the response time of the server a lot. In a word, these solutions not only effectively improve server performance, but also economic, simple and convenient.