用java写一个贪吃蛇游戏

好的，以下是一个简单的贪吃蛇游戏的Java代码：

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.LinkedList;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class SnakeGame extends JPanel implements Runnable, KeyListener {

    private static final long serialVersionUID = 1L;

    private static final int WIDTH = 500;
    private static final int HEIGHT = 500;
    private static final int DOT_SIZE = 10;
    private static final int ALL_DOTS = 900;
    private static final int RAND_POS = 29;
    private static final int DELAY = 140;

    private final int x[] = new int[ALL_DOTS];
    private final 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 Thread thread;
    private Random random;

    public SnakeGame() {
        initGame();
    }

    public void initGame() {
        addKeyListener(this);
        setBackground(Color.black);
        setFocusable(true);

        setPreferredSize(new java.awt.Dimension(WIDTH, HEIGHT));
        initVariables();
    }

    public void initVariables() {
        dots = 3;

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

        random = new Random();
        locateApple();

        thread = new Thread(this);
        thread.start();
    }

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

        doDrawing(g);
    }

    public void doDrawing(Graphics g) {
        if (inGame) {
            g.setColor(Color.red);
            g.fillOval(apple_x, apple_y, DOT_SIZE, DOT_SIZE);

            for (int z = 0; z < dots; z++) {
                if (z == 0) {
                    g.setColor(Color.green);
                } else {
                    g.setColor(Color.yellow);
                }

                g.fillOval(x[z], y[z], DOT_SIZE, DOT_SIZE);
            }

            // Sync graphics state
            java.awt.Toolkit.getDefaultToolkit().sync();
        } else {
            gameOver(g);
        }
    }

    public void gameOver(Graphics g) {
        String msg = "Game Over";
        java.awt.Font font = new java.awt.Font("Helvetica", java.awt.Font.BOLD, 14);
        java.awt.FontMetrics metrics = getFontMetrics(font);

        g.setColor(Color.white);
        g.setFont(font);
        g.drawString(msg, (WIDTH - metrics.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) {
            thread.interrupt();
        }
    }

    public void locateApple() {
        int r = random.nextInt(RAND_POS);
        apple_x = ((r * DOT_SIZE));

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

    @Override
    public void run() {
        while (true) {
            if (inGame) {
                checkApple();
                checkCollision();
                move();
            }

            repaint();

            try {
                Thread.sleep(DELAY);
            } catch (InterruptedException ex) {
                ex.printStackTrace();
            }
        }
    }

    @Override
    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;
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {

    }

    @Override
    public void keyTyped(KeyEvent e) {

    }

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

这个代码实现了一个简单的贪吃蛇游戏，可以使用上下左右箭头键来操控蛇的移动方向。