java 贪吃蛇小游戏

以下是一个简单的 Java 贪吃蛇小游戏的示例代码：

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

public class SnakeGame extends JFrame implements KeyListener {
    private static final long serialVersionUID = 1L;
    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 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() {
        addKeyListener(this);
        setTitle("Snake Game");
        setBackground(Color.black);
        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();

        initGame();
    }

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

        locateApple();

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

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

        if (inGame) {
            g.drawImage(apple, apple_x, apple_y, this);

            for (int z = 0; z < dots; z++) {
                if (z == 0)
                    g.drawImage(head, x[z], y[z], this);
                else
                    g.drawImage(ball, x[z], y[z], 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 z = dots; z > 0; z--) {
            x[z] = x[(z - 1)];
            y[z] = y[(z - 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 z = dots; z > 0; z--) {
            if ((z > 4) && (x[0] == x[z]) && (y[0] == y[z])) {
                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 keyReleased(KeyEvent e) {
    }

    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 keyTyped(KeyEvent e) {
    }

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

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

在代码中，`initGame()` 方法初始化游戏，`paint(Graphics g)` 方法绘制游戏界面，`checkApple()` 方法检查是否吃到了苹果，`move()` 方法移动贪吃蛇，`checkCollision()` 方法检查是否发生碰撞，`locateApple()` 方法随机生成苹果的位置，`keyPressed(KeyEvent e)` 方法处理键盘事件。运行代码后，即可开始玩贪吃蛇小游戏。