如何在半透明度的applet中绘制填充矩形？

import java.awt.*;
import java.applet.Applet;

public class TransparentRectangle extends Applet {
    @Override
    public void paint(Graphics g) {
        // 设置背景颜色为透明
        setBackground(new Color(0, 0, 0, 0));

        // 创建一个半透明的画布
        Graphics2D g2d = (Graphics2D) g;
        Composite composite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);
        g2d.setComposite(composite);

        // 绘制填充矩形
        g2d.setColor(Color.RED);
        g2d.fillRect(50, 50, 100, 100);
    }
}