写一个基于java的贪吃蛇游戏的代码

以下是一个基于 Java 的简单贪吃蛇游戏的代码：

import java.awt.Color;
import java.awt.Dimension;
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 Thread thread;
    private boolean isRunning;

    private LinkedList<Point> snake;
    private int direction;
    private Point fruit;

    public SnakeGame() {
        setPreferredSize(new Dimension(WIDTH, HEIGHT));
        setFocusable(true);
        addKeyListener(this);

        snake = new LinkedList<Point>();
        snake.add(new Point(0, 0));
        direction = KeyEvent.VK_RIGHT;

        fruit = new Point(0, 0);
        placeFruit();

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

    public void run() {
        while (isRunning) {
            try {
                Thread.sleep(100);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            update();
            repaint();
        }
    }

    private void update() {
        Point head = snake.peekFirst();
        Point newPoint = head;
        switch (direction) {
        case KeyEvent.VK_LEFT:
            newPoint = new Point(head.x - 1, head.y);
            break;
        case KeyEvent.VK_RIGHT:
            newPoint = new Point(head.x + 1, head.y);
            break;
        case KeyEvent.VK_UP:
            newPoint = new Point(head.x, head.y - 1);
            break;
        case KeyEvent.VK_DOWN:
            newPoint = new Point(head.x, head.y + 1);
            break;
        }
        if (newPoint.equals(fruit)) {
            snake.addFirst(newPoint);
            placeFruit();
        } else {
            snake.removeLast();
            if (snake.contains(newPoint)) {
                isRunning = false;
            }
            snake.addFirst(newPoint);
        }
        if (head.x < 0 || head.x >= WIDTH || head.y < 0 || head.y >= HEIGHT) {
            isRunning = false;
        }
    }

    private void placeFruit() {
        Random rand = new Random();
        int x = rand.nextInt(WIDTH);
        int y = rand.nextInt(HEIGHT);
        fruit.setLocation(x, y);
    }

    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.setColor(Color.GREEN);
        for (Point p : snake) {
            g.fillRect(p.x, p.y, 1, 1);
        }
        g.setColor(Color.RED);
        g.fillRect(fruit.x, fruit.y, 1, 1);
    }

    public void keyPressed(KeyEvent e) {
        int newDirection = e.getKeyCode();
        if (newDirection == KeyEvent.VK_LEFT && direction != KeyEvent.VK_RIGHT) {
            direction = newDirection;
        } else if (newDirection == KeyEvent.VK_RIGHT && direction != KeyEvent.VK_LEFT) {
            direction = newDirection;
        } else if (newDirection == KeyEvent.VK_UP && direction != KeyEvent.VK_DOWN) {
            direction = newDirection;
        } else if (newDirection == KeyEvent.VK_DOWN && direction != KeyEvent.VK_UP) {
            direction = newDirection;
        }
    }

    public void keyTyped(KeyEvent e) {
    }

    public void keyReleased(KeyEvent e) {
    }

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

这个游戏使用了 Java Swing 组件进行界面绘制，通过 `LinkedList` 存储贪吃蛇的每一个节点，并使用 `Point` 类型记录每个节点的坐标。通过 `KeyListener` 监听键盘事件，改变贪吃蛇的运动方向。游戏中使用了一个 `Thread` 对游戏进行更新，保证游戏的流畅性。