基于图书管理场景对空对象模式的深入认识

在Java程序设计中,经常会遇到java.lang.NullPointerException空指针异常,在客户端总是需要判断某一对象是否为空对象,这使得客户端掌握了主动权,且程序不够友好。文章从这些常见的问题出发,分析了一个在经典的23种软件设计模式以外的模式——空对象模式,通过图书管理的场景引出问题,并合理地运用空对象模式对问题进行分析和解决,讨论了空对象模式的实现方式及应用场景,阐述了对空对象模式的优缺点分析与对软件设计模式的深入理解。

Design and Implementation of mobile GIS application based on Android

This paper analyzes the key technology of mobile GIS development, discusses the design method of mobile GIS spatial data management, visualization of spatial data And Spatial data query, tinder Object oriented mode. And we develop a set of mobile GIS basic software platform in the Android platform, and tested in the mainstream smart mobile phone with Android operating system, test results show that the software platform can run smoothly. Other users can development a variety of mobile GIS to call the platform through an application service interface.