说明：  以一个简单的小游戏为例子，比较全面的介绍了MIDP图形编程方法。 包括以Screen为基础的高层界面和以Canvas为基础的底层界面开发都有涉及。
(a simple little game, for example, a more comprehensive introduction to the MIDP graphics programming method. Screen including senior-based interface and Canvas based on the bottom interface development are involved.)