用Java语言编写一个简单的贪吃蛇游戏

好的，以下是一个简单的贪吃蛇游戏的Java代码：

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

public class SnakeGame extends JFrame implements KeyListener, ActionListener {
    private int width = 15;
    private int height = 15;
    private int size = 20;
    private int[][] map = new int[width][height];
    private int snakeLength = 3;
    private int[] snakeX = new int[width * height];
    private int[] snakeY = new int[width * height];
    private int foodX;
    private int foodY;
    private int direction = 39;
    private Timer timer;

    public SnakeGame() {
        setTitle("贪吃蛇游戏");
        setSize(width * size + 6, height * size + 28);
        setResizable(false);
        setLocationRelativeTo(null);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        addKeyListener(this);

        init();

        timer = new Timer(200, this);
        timer.start();

        setVisible(true);
    }

    private void init() {
        for (int i = 0; i < width; i++) {
            for (int j = 0; j < height; j++) {
                map[i][j] = 0;
            }
        }

        for (int i = 0; i < snakeLength; i++) {
            snakeX[i] = width / 2 - i;
            snakeY[i] = height / 2;
            map[snakeX[i]][snakeY[i]] = 1;
        }

        generateFood();
    }

    private void generateFood() {
        boolean valid = false;

        while (!valid) {
            foodX = (int) (Math.random() * width);
            foodY = (int) (Math.random() * height);

            if (map[foodX][foodY] == 0) {
                valid = true;
            }
        }
    }

    public void paint(Graphics g) {
        g.setColor(Color.WHITE);
        g.fillRect(0, 0, width * size, height * size);

        g.setColor(Color.BLACK);
        for (int i = 0; i <= width; i++) {
            g.drawLine(i * size, 0, i * size, height * size);
        }
        for (int i = 0; i <= height; i++) {
            g.drawLine(0, i * size, width * size, i * size);
        }

        g.setColor(Color.GREEN);
        g.fillRect(foodX * size, foodY * size, size, size);

        g.setColor(Color.RED);
        for (int i = 0; i < snakeLength; i++) {
            g.fillRect(snakeX[i] * size, snakeY[i] * size, size, size);
        }
    }

    public void keyPressed(KeyEvent e) {
        int key = e.getKeyCode();

        if ((key == KeyEvent.VK_LEFT || key == KeyEvent.VK_A) && direction != 39) {
            direction = 37;
        }
        if ((key == KeyEvent.VK_UP || key == KeyEvent.VK_W) && direction != 40) {
            direction = 38;
        }
        if ((key == KeyEvent.VK_RIGHT || key == KeyEvent.VK_D) && direction != 37) {
            direction = 39;
        }
        if ((key == KeyEvent.VK_DOWN || key == KeyEvent.VK_S) && direction != 38) {
            direction = 40;
        }
    }

    public void keyReleased(KeyEvent e) {}

    public void keyTyped(KeyEvent e) {}

    public void actionPerformed(ActionEvent e) {
        int x = snakeX[0];
        int y = snakeY[0];

        if (direction == 37) {
            x--;
        }
        if (direction == 38) {
            y--;
        }
        if (direction == 39) {
            x++;
        }
        if (direction == 40) {
            y++;
        }

        if (x < 0 || x >= width || y < 0 || y >= height || map[x][y] == 1) {
            timer.stop();
            JOptionPane.showMessageDialog(null, "游戏结束");
            System.exit(0);
        }

        if (x == foodX && y == foodY) {
            snakeLength++;
            map[foodX][foodY] = 1;
            generateFood();
        } else {
            map[snakeX[snakeLength - 1]][snakeY[snakeLength - 1]] = 0;
        }

        for (int i = snakeLength - 1; i > 0; i--) {
            snakeX[i] = snakeX[i - 1];
            snakeY[i] = snakeY[i - 1];
        }
        snakeX[0] = x;
        snakeY[0] = y;
        map[x][y] = 1;

        repaint();
    }

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

代码中使用了Java的Swing库来实现界面，在主函数中创建了一个`SnakeGame`对象，该对象实现了`KeyListener`和`ActionListener`接口，分别用于处理键盘事件和定时器事件。

游戏中使用一个二维数组`map`来表示地图，其中0表示空格，1表示蛇身，使用`snakeX`和`snakeY`两个数组来记录蛇身的位置，使用`snakeLength`来记录蛇身的长度。在定时器事件中，根据当前方向移动蛇身，检测是否与食物碰撞，更新蛇身位置和长度，重新生成食物，最后重绘整个界面。

具体实现细节请参考代码注释。