JPanel渐变背景

我用谷歌搜索了一下，但找不到正确的答案。我有一个JPanel，我希望它有一个从上到下的渐变。我只打算用两种颜色。如何实现此目标？

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解决方案

转到这里：

import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class TestPanel extends JPanel {

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g;
        g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
        int w = getWidth(), h = getHeight();
        Color color1 = Color.RED;
        Color color2 = Color.GREEN;
        GradientPaint gp = new GradientPaint(0, 0, color1, w, h, color2);
        g2d.setPaint(gp);
        g2d.fillRect(0, 0, w, h);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                TestPanel panel = new TestPanel();
                frame.add(panel);
                frame.setSize(200, 200);
                frame.setLocationRelativeTo(null);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}