说明：  工程演示了App开发的初级控件相关用法，包括：屏幕显示基础（像素、颜色、分辨率）、简单布局的用法（基本视图、线性布局、滚动视图）、简单控件的用法（文本视图、按钮、图像视图、图像按钮）、简单图形的用法（状态列表图形、形状图形、九宫格图片），以及实战项目“简单计算器”。 通过本章的代码练习，应能掌握以下App的开发：简单计算器。
(The project demonstrates the usage of primary controls developed by App, including: the screen display base (pixel, color, resolution), the usage of simple layout (basic view, linear layout, rolling view), the usage of simple controls (text view, button, image view, image button), and simple graphics usage State list graphics, shape graphics, nine palace picture), as well as actual combat project "simple calculator". Through the code exercises in this chapter, you should be able to master the following App development: simple calculator.)