用Java写一个贪吃蛇

非常感谢您的提问。以下是使用Java编写一个简单的贪吃蛇游戏的示例代码：

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

public class Snake extends JPanel implements ActionListener {
    private final int WIDTH = 500;
    private final int HEIGHT = 500;
    private final int DOT_SIZE = 10;
    private final int ALL_DOTS = 2500;
    private final int RAND_POS = 29;
    private final int DELAY = 140;

    private int[] x = new int[ALL_DOTS];
    private int[] y = new int[ALL_DOTS];
    private int dots;
    private int apple_x;
    private int apple_y;

    private boolean left = false;
    private boolean right = true;
    private boolean up = false;
    private boolean down = false;
    private boolean inGame = true;

    private Timer timer;
    private Image ball;
    private Image apple;
    private Image head;

    public Snake() {
        addKeyListener(new TAdapter());
        setBackground(Color.black);
        setPreferredSize(new Dimension(WIDTH, HEIGHT));

        ImageIcon iid = new ImageIcon(this.getClass().getResource("dot.png"));
        ball = iid.getImage();

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

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

        initGame();
    }

    public void initGame() {
        dots = 3;
        for (int i = 0; i < dots; i++) {
            x[i] = 50 - i * 10;
            y[i] = 50;
        }

        locateApple();

        timer = new Timer(DELAY, this);
        timer.start();
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);

        doDrawing(g);
    }

    public void doDrawing(Graphics 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 move() {
        for (int i = dots; i > 0; i--) {
            x[i] = x[(i - 1)];
            y[i] = y[(i - 1)];
        }

        if (left) {
            x[0] -= DOT_SIZE;
        }

        if (right) {
            x[0] += DOT_SIZE;
        }

        if (up) {
            y[0] -= DOT_SIZE;
        }

        if (down) {
            y[0] += DOT_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 * DOT_SIZE;

        r = (int) (Math.random() * RAND_POS);
        apple_y = r * DOT_SIZE;
    }

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

        repaint();
    }

    private class TAdapter extends KeyAdapter {
        public void keyPressed(KeyEvent e) {
            int key = e.getKeyCode();

            if ((key == KeyEvent.VK_LEFT) && (!right)) {
                left = true;
                up = false;
                down = false;
            }

            if ((key == KeyEvent.VK_RIGHT) && (!left)) {
                right = true;
                up = false;
                down = false;
            }

            if ((key == KeyEvent.VK_UP) && (!down)) {
                up = true;
                right = false;
                left = false;
            }

            if ((key == KeyEvent.VK_DOWN) && (!up)) {
                down = true;
                right = false;
                left = false;
            }
        }
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Snake");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Snake game = new Snake();
        frame.add(game);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}

注意: 示例代码中用到的图片资源可以自行准备或在代码当前路径下新建一个"dot.png"、"apple.png"、"head.png"文件，并在其中放入相应图片。

希望您喜欢这个小游戏!