更改 JButton 渐变颜色，但仅适用于一个按钮，而不是所有按钮

您可以重写实例的 paintComponent 方法，并使用实现 Paint 接口的下列类之一绘制其 Graphics 对象：JButton

• 渐变画。
• LinearGradientPaint
• 多级画
• 径向渐变画

import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;

public final class JGradientButtonDemo {
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                createAndShowGUI();         
            }
        });
    }

    private static void createAndShowGUI() {
        final JFrame frame = new JFrame("Gradient JButton Demo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().setLayout(new FlowLayout());
        frame.add(JGradientButton.newInstance());
        frame.setSize(new Dimension(300, 150)); // used for demonstration
        //frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    private static class JGradientButton extends JButton {
        private JGradientButton() {
            super("Gradient Button");
            setContentAreaFilled(false);
            setFocusPainted(false); // used for demonstration
        }

        @Override
        protected void paintComponent(Graphics g) {
            final Graphics2D g2 = (Graphics2D) g.create();
            g2.setPaint(new GradientPaint(
                    new Point(0, 0), 
                    Color.WHITE, 
                    new Point(0, getHeight()), 
                    Color.PINK.darker()));
            g2.fillRect(0, 0, getWidth(), getHeight());
            g2.dispose();

            super.paintComponent(g);
        }

        public static JGradientButton newInstance() {
            return new JGradientButton();
        }
    }
}

对mre答案的一点改进：

private static final class JGradientButton extends JButton{
    private JGradientButton(String text){
        super(text);
        setContentAreaFilled(false);
    }

    @Override
    protected void paintComponent(Graphics g){
        Graphics2D g2 = (Graphics2D)g.create();
        g2.setPaint(new GradientPaint(
                new Point(0, 0), 
                getBackground(), 
                new Point(0, getHeight()/3), 
                Color.WHITE));
        g2.fillRect(0, 0, getWidth(), getHeight()/3);
        g2.setPaint(new GradientPaint(
                new Point(0, getHeight()/3), 
                Color.WHITE, 
                new Point(0, getHeight()), 
                getBackground()));
        g2.fillRect(0, getHeight()/3, getWidth(), getHeight());
        g2.dispose();

        super.paintComponent(g);
    }
}