创建一个Jfr a me对象，设置器关闭操作为推出应用程序 从JPanel 派生出一个绘画类，让其具有一定的绘图功能，设置一个定时器，周期的更新绘画对象，产生动画效果-Create a Jfr a me object setter closing operation for the introduction of applications derived JPanel a painting class, let it have some drawing functions, a timer i