报错：
Exception in thread "main" java.lang.IllegalArgumentException: input == null!
at java.desktop/javax.imageio.ImageIO.read(ImageIO.java:1400)
at game01/cn.sxt.game.GameUtil.getImage(GameUtil.java:22)
at game01/cn.sxt.game.MyGameFrame.<init>(MyGameFrame.java:11)
at game01/cn.sxt.game.MyGameFrame.main(MyGameFrame.java:40)
解决方法：