圆角高亮Button

swing的JButton方方正正，看久了总觉得审美疲劳了，看了apple上的按钮，就舒服多了。借助java2D，要做类似那种按钮也不是不可能的。
要做到这个效果，可以重写BasicButtonUI然后给调用JButton的setUI，也可以继承JButton重写部分方法。两者原理都一样，我这里用的是第二种。原理就是重新绘制Jbutton包括按钮，边框等，也就是重写paintComponent(Graphics g).

public class BasicButton extends JButton {

	/**
	 * 
	 */
	private static final long serialVersionUID = 1L;

	public static final Color BUTTON_COLOR1 = new Color(125, 161, 237);
	public static final Color BUTTON_COLOR2 = new Color(91, 118, 173);
	public static final Color BUTTON_BAK_COLOR1_1 = new Color(108, 135, 210,
			179);
	public static final Color BUTTON_BAK_COLOR1_2 = new Color(108, 135, 210,
			255);
	public static final Color BUTTON_BAK_COLOR2_1 = new Color(180, 230, 250,
			179);
	public static final Color BUTTON_BAK_COLOR2_2 = new Color(180, 230, 250,
			255);
	public static final Color BUTTON_FOREGROUND_COLOR = Color.BLACK;
	private boolean hover;

	public BasicButton(String text) {
		super(text);
            //步骤1
		setBorderPainted(false);
		setFocusPainted(false);
		setContentAreaFilled(false);

		setForeground(BUTTON_FOREGROUND_COLOR);
		addMouseListener(new MouseAdapter() {
			@Override
			public void mouseEntered(MouseEvent e) {
				hover = true;
				repaint();
			}

			@Override
			public void mouseExited(MouseEvent e) {
				hover = false;
				repaint();
			}
		});
	}

	@Override
	protected void paintComponent(Graphics g) {
		Graphics2D g2d = (Graphics2D) g.create();
		int h = getHeight();
		int w = getWidth();
//		Color color2 = BUTTON_BAK_COLOR1_2;
//		Color color1 = BUTTON_BAK_COLOR2_2;
		float tran = 1F;
		if (!hover) {
			tran = 0.7F;
//			color2 = BUTTON_BAK_COLOR1_1;
//			color1 = BUTTON_BAK_COLOR2_1;
		}
            //步骤2
		g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
				RenderingHints.VALUE_ANTIALIAS_ON);
		GradientPaint p1;
		GradientPaint p2;
		if (getModel().isPressed()) {
			p1 = new GradientPaint(0, 0, new Color(0, 0, 0), 0, h - 1,
					new Color(100, 100, 100));
			p2 = new GradientPaint(0, 1, new Color(0, 0, 0, 50), 0, h - 3,
					new Color(255, 255, 255, 100));
		} else {
			p1 = new GradientPaint(0, 0, new Color(100, 100, 100), 0, h - 1,
					new Color(0, 0, 0));
			p2 = new GradientPaint(0, 1, new Color(255, 255, 255, 100), 0,
					h - 3, new Color(0, 0, 0, 50));
		}
//设置透明度

             g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
				tran));
		Shape clip = g2d.getClip();
           //绘制整个按钮
		RoundRectangle2D.Float r2d = new RoundRectangle2D.Float(0, 0, w - 1,
				h - 1, h, h);
		g2d.clip(r2d);
		GradientPaint gp = new GradientPaint(0.0F, 0.0F, BUTTON_COLOR1, 0.0F,
				h, BUTTON_COLOR2, true);
		g2d.setPaint(gp);
		g2d.fillRect(0, 0, w, h);
                //鼠标移入就绘制立体效果
		if (hover) {
			RoundRectangle2D.Float r2d2 = new RoundRectangle2D.Float(5, 2,
					w - 10, h / 2 - 1, h / 2, h / 2);
			g2d.clip(r2d2);
			GradientPaint gp2 = new GradientPaint(0.0F, 0.0F, BUTTON_BAK_COLOR2_2, 0.0F,
					h / 2, BUTTON_BAK_COLOR1_2, true);
			g2d.setPaint(gp2);
			g2d.fillRect(5, 2, w - 10, h / 2);
		}
		g2d.setClip(clip);
                //绘制边框
		g2d.setPaint(p1);
		g2d.drawRoundRect(0, 0, w - 1, h - 1, h, h);
		g2d.setPaint(p2);
		g2d.drawRoundRect(1, 1, w - 3, h - 3, h - 2, h - 2);
		g2d.dispose();
		super.paintComponent(g);
	}
}

基本步骤就是：
1.先调用父类的方法，让父类不用绘制边框、不用绘制焦点、不用绘制内容，我们自己来完成这些东西。
2.调用抗锯齿的api，让我们paint出来的线条平滑，要不然会有相当难看的锯齿。
3.设置透明度。这个主要是为了做出鼠标移入、移出的效果。我这里是移入按钮，按钮颜色加深并且会有视觉效果上的“凸起”立体感；移出就颜色变浅，凸起感消失，恢复原样了。
4.绘制整个按钮。生成一个圆角矩形，并用由上到下的渐进色填充，这就是按钮的整体效果。
5.如果鼠标移入就绘制立体效果。在这里我是先生成一个高度为按钮一半的圆角矩形，然后从上到下用渐进色填充，最下面的颜色就是按钮本身在中间位置的颜色，这样看起来上面是白的，好像反光的立体效果。
6.绘制边框。用于点击效果的显示。
如果要真正想apple那样的效果，就还需要用另外的区域来模糊化下半个按钮部分，需要涉及到调整颜色之类的，我这就没做了，大概的效果图如下：
正常状态
[img]/upload/attachment/104244/907458ff-0c94-32c6-99e7-d591c08dc051.png[/img]
鼠标移上去
[img]/upload/attachment/104246/65f1b2ad-2417-3a7c-9377-9a52fd7aaed3.png[/img]
鼠标按下去
[img]/upload/attachment/104248/9d148408-b85d-3d22-8e51-c44ffbafe0f4.png[/img]