用java帮我写一个贪吃蛇

好的，下面是一个简单的贪吃蛇游戏的Java代码实现，你可以根据自己的需要进行修改和完善：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class Snake extends JFrame implements KeyListener, ActionListener {
    private final int WIDTH = 500;
    private final int HEIGHT = 500;
    private final int CELL_SIZE = 20;
    private final int MAX_DOTS = (WIDTH * HEIGHT) / (CELL_SIZE * CELL_SIZE);
    private final int RAND_POS = WIDTH / CELL_SIZE;
    private final int DELAY = 140;

    private int dots;
    private int apple_x;
    private int apple_y;
    private int[] x = new int[MAX_DOTS];
    private int[] y = new int[MAX_DOTS];
    private boolean leftDirection = false;
    private boolean rightDirection = true;
    private boolean upDirection = false;
    private boolean downDirection = false;
    private boolean inGame = true;
    private Timer timer;
    private Image ball;
    private Image apple;
    private Image head;

    public Snake() {
        setTitle("Snake");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setSize(WIDTH, HEIGHT);
        setResizable(false);
        setLocationRelativeTo(null);
        addKeyListener(this);
        initGame();
    }

    public void initGame() {
        dots = 3;
        for (int i = 0; i < dots; i++) {
            x[i] = 50 - i * CELL_SIZE;
            y[i] = 50;
        }
        locateApple();
        timer = new Timer(DELAY, this);
        timer.start();
        loadImage();
    }

    public void loadImage() {
        ImageIcon iid = new ImageIcon(getClass().getResource("dot.png"));
        ball = iid.getImage();

        ImageIcon iia = new ImageIcon(getClass().getResource("apple.png"));
        apple = iia.getImage();

        ImageIcon iih = new ImageIcon(getClass().getResource("head.png"));
        head = iih.getImage();
    }

    public void move() {
        for (int i = dots; i > 0; i--) {
            x[i] = x[i - 1];
            y[i] = y[i - 1];
        }
        if (leftDirection) {
            x[0] -= CELL_SIZE;
        }
        if (rightDirection) {
            x[0] += CELL_SIZE;
        }
        if (upDirection) {
            y[0] -= CELL_SIZE;
        }
        if (downDirection) {
            y[0] += CELL_SIZE;
        }
    }

    public void checkCollision() {
        for (int i = dots; i > 0; i--) {
            if ((i > 4) && (x[0] == x[i]) && (y[0] == y[i])) {
                inGame = false;
            }
        }
        if (y[0] >= HEIGHT) {
            inGame = false;
        }
        if (y[0] < 0) {
            inGame = false;
        }
        if (x[0] >= WIDTH) {
            inGame = false;
        }
        if (x[0] < 0) {
            inGame = false;
        }
        if (!inGame) {
            timer.stop();
        }
    }

    public void locateApple() {
        int r = (int) (Math.random() * RAND_POS);
        apple_x = r * CELL_SIZE;
        r = (int) (Math.random() * RAND_POS);
        apple_y = r * CELL_SIZE;
    }

    public void paint(Graphics g) {
        super.paint(g);
        if (inGame) {
            g.drawImage(apple, apple_x, apple_y, this);
            for (int i = 0; i < dots; i++) {
                if (i == 0) {
                    g.drawImage(head, x[i], y[i], this);
                } else {
                    g.drawImage(ball, x[i], y[i], this);
                }
            }
            Toolkit.getDefaultToolkit().sync();
        } else {
            gameOver(g);
        }
    }

    public void gameOver(Graphics g) {
        String msg = "Game Over";
        Font small = new Font("Helvetica", Font.BOLD, 14);
        FontMetrics metr = getFontMetrics(small);
        g.setColor(Color.white);
        g.setFont(small);
        g.drawString(msg, (WIDTH - metr.stringWidth(msg)) / 2, HEIGHT / 2);
    }

    public void checkApple() {
        if ((x[0] == apple_x) && (y[0] == apple_y)) {
            dots++;
            locateApple();
        }
    }

    public void actionPerformed(ActionEvent e) {
        if (inGame) {
            checkApple();
            checkCollision();
            move();
        }
        repaint();
    }

    public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();
        if ((key == KeyEvent.VK_LEFT) && (!rightDirection)) {
            leftDirection = true;
            upDirection = false;
            downDirection = false;
        }
        if ((key == KeyEvent.VK_RIGHT) && (!leftDirection)) {
            rightDirection = true;
            upDirection = false;
            downDirection = false;
        }
        if ((key == KeyEvent.VK_UP) && (!downDirection)) {
            upDirection = true;
            rightDirection = false;
            leftDirection = false;
        }
        if ((key == KeyEvent.VK_DOWN) && (!upDirection)) {
            downDirection = true;
            rightDirection = false;
            leftDirection = false;
        }
    }

    public void keyReleased(KeyEvent e) {
    }

    public void keyTyped(KeyEvent e) {
    }

    public static void main(String[] args) {
        new Snake().setVisible(true);
    }
}

上面的代码实现了一个简单的贪吃蛇游戏，在窗口中显示出贪吃蛇和苹果，并且可以用键盘控制贪吃蛇的移动方向。你可以自己尝试运行一下，看看效果如何。