设Shape是圆、矩形、三角形共享的类，含有求圆的周长和面积的方法getCircumference()与getArea()，以及属性DEscr iptION以描述几何体的特征，试设计相关类圆、矩形、三角形类，并求圆、矩形、三角形的周长与面积。设计相应的测试类，求实际对象的面积与方法。（要求分别将Shape类用抽象、接口实现）-Let Shape is round, rectangular, triangular shared class containing the perimeter and area of ​ ​ circular method getCircumference () and getArea (), as well as property DEscr iptION to describe the characteristics of geometry, try to design related classes circles, rectangles, triangles class, and of circular, rectangular, triangular perimeter and area. Design appropriate test class, find the area of ​ ​ the actual object and method. (Requires separately with the Shape class is abstract, interface)