说明：  让Swing控件也有渐隐和渐显的效果：重写Swing的public void paint(Graphics g)方法。Swing的一切样式说白了都是利用paint方法“画”上去的，所以说Swing比较慢，当然如果我们考虑Swing主要用来做客户端显示 的，稍微慢一点也是可以接受的。
(Swing controls also have the effect of fade and fade: rewrite Swing public void paint (Graphics g) method. All styles of Swing said white paint method is the use of " paint up, so that Swing is slower, of course, if we consider that Swing is mainly used for client-side display, a little bit slower is acceptable.)