Java hunting and shooting game code based on Swing

package Game;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.JPanel;
public class BackgroundPanel extends JPanel {
        private static final long serialVersionUID = 1L;
        private Image image;// 背景图片
        public BackgroundPanel() {
                setOpaque(false);
                setLayout(null);
        }
        public void setImage(Image image) {
                this.image = image;
        }
        /**
         * 画出背景
         */
        protected void paintComponent(Graphics g) {
                if (image != null) {
                        // 图片宽度
                        int width = getWidth();
                        // 图片高度
                        int height = getHeight();
                        // 画出图片
                        g.drawImage(image, 0, 0, width, height, this);
                }
                super.paintComponent(g);
        }
}

package Game;
import java.awt.Container;
import java.awt.event.*;
import javax.swing.*;
public class BirdLabel extends JLabel implements Runnable {
        private static final long serialVersionUID = 1L;
        // 随机生成线程的休眠时间，即控制小鸟移动速度
        private int sleepTime = (int) (Math.random() * 300) + 5;
        private int y = 100;
        private Thread thread;// 将线程作为成员变量
        private Container parent;
        private int score = 15;// 该类角色对应的分数
        /**
         * 构造方法
         */
        public BirdLabel() {
                super();
                // 创建小鸟图标对象
                ImageIcon icon = new ImageIcon(getClass().getResource("bird.gif"));
                setIcon(icon);// 设置控件图标
                addMouseListener(new MouseAction());// 添加鼠标事件监听器
                // 添加控件事件监听器
                addComponentListener(new ComponentAction());
                thread = new Thread(this);// 创建线程对象
        }