100％java开发的电子地图软件，电子地图放大、缩小、漫游、测距，图层查询，最短路径计算等功能。(只有class和地图文件，无源码)-100% java development of electronic mapping software, electronic maps to zoom, roaming, location, layers inquiries, the shortest path calculation capabilities. (Only class documents

抽象类Shape，抽象方法：计算面积和显示面积，派生子类矩形和三角形-Abstract class Shape, abstract methods: calculating the area and display area, derived subclass of rectangular and triangular