绘制JButton圆角效果

在网上看见一篇非常好的技术文章，此文章是将JButton的四角绘制成圆角形状。这个在我们平时应用也非常多。就我而言，如果我来设计一个按钮JButton的圆角效果，我会采用：

（1）先让JButton的变成透明色
（2）然后，加入一个具有圆角的图片

现在我还是希望利用程序来绘制JButton的圆角效果，所以我将在网上看见的代码给大家一起分享。代码如下：

第一：重新继承JButton组件，然后利用Java 2D绘制图形的类将JButton组件重写。

package com.gxa.edu.test;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.RoundRectangle2D;

import javax.swing.JButton;

public class RButton extends JButton {
    private static final long serialVersionUID = 39082560987930759L;
    public static final Color BUTTON_COLOR1 = new Color(205, 255, 205);
    public static final Color BUTTON_COLOR2 = new Color(51, 154, 47);
    // 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_FOREGROUND_COLOR = Color.WHITE;
    private boolean hover;

    public RButton(String name) {
        this.setText(name);
        setFont(new Font("system", Font.PLAIN, 12));
        setBorderPainted(false);
        setForeground(BUTTON_COLOR2);
        setFocusPainted(false);
        setContentAreaFilled(false);
        addMouseListener(new MouseAdapter() {
            @Override
            public void mouseEntered(MouseEvent e) {
                setForeground(BUTTON_FOREGROUND_COLOR);
                hover = true;
                repaint();
            }

            @Override
            public void mouseExited(MouseEvent e) {
                setForeground(BUTTON_COLOR2);
                hover = false;
                repaint();
            }
        });
    }

    @Override
    protected void paintComponent(Graphics g) {
        Graphics2D g2d = (Graphics2D) g.create();
        int h = getHeight();
        int w = getWidth();
        float tran = 1F;
        if (!hover) {
            tran = 0.3F;
        }

        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));
        }
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER,
                tran));
        RoundRectangle2D.Float r2d = new RoundRectangle2D.Float(0, 0, w - 1,
                h - 1, 20, 20);
        Shape clip = g2d.getClip();
        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);
        g2d.setClip(clip);
        g2d.setPaint(p1);
        g2d.drawRoundRect(0, 0, w - 1, h - 1, 20, 20);
        g2d.setPaint(p2);
        g2d.drawRoundRect(1, 1, w - 3, h - 3, 18, 18);
        g2d.dispose();
        super.paintComponent(g);
    }
}

第二：设计一个简单的JFrame窗口，加入此JButton，然后看看最终的效果

package com.gxa.edu.test;

import java.awt.FlowLayout;

import javax.swing.JFrame;

public class TestButtonFrame extends JFrame {
	DepthButton b1;
	RButton b2;
	
	public TestButtonFrame() {
		super("测试");
		this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		this.setSize(300, 200);
		this.getContentPane().setLayout(new FlowLayout());
		b1 = new DepthButton("depthButton");
		b2 = new RButton("RButton");
		this.getContentPane().add(b1);
		this.getContentPane().add(b2);
		
		this.setVisible(true);
	}

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		new TestButtonFrame();
	}

}