怎么在JFrame或JPanel里添加背景图片

import java.awt.*;import javax.swing.*;class ImagePanel extends JPanel {    private Image backgroundImage;    ImagePanel() {        // 从系统中加载图片        backgroundImage = new ImageIcon("image address").getImage();    }        @Override    protected void paintComponent(Graphics g) {        super.paintComponent(g);                if (backgroundImage != null) {            g.drawImage(backgroundImage, 0, 0, getWidth(), getHeight(), this);        }    }}