用java语言编写一个贪吃蛇游戏代码

以下是Java语言编写的简单贪吃蛇游戏代码：

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

public class SnakeGame extends JFrame implements ActionListener {
    private final int WIDTH = 300;
    private final int HEIGHT = 300;
    private final int DOT_SIZE = 10;
    private final int ALL_DOTS = 900;
    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 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 SnakeGame() {
        setTitle("Snake Game");
        setBackground(Color.gray);
        setResizable(false);
        setSize(WIDTH, HEIGHT);

        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();

        addKeyListener(new TAdapter());

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

        initGame();
    }

    public void initGame() {
        dots = 3;

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

        locateApple();

        inGame = true;
    }

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

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

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

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

        if (downDirection) {
            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) && (!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 static void main(String[] args) {
        new SnakeGame().setVisible(true);
    }
}

在代码中，我们使用了Java Swing库，创建了一个JFrame窗口，通过继承JFrame类实现，利用paint()方法绘制游戏画面，并且使用了Timer类来控制游戏帧率，使用ImageIcon读取了游戏素材。同时，我们还实现了一些游戏逻辑，比如蛇的移动、碰撞检测、吃苹果等。最后，我们在main()方法中新建了一个SnakeGame对象并可见。