使用JAVA语言实现贪吃蛇，要求实现“开始”“暂停”“加速”三个额外功能

好的，我可以为您提供一个简单的贪吃蛇游戏的Java实现，同时添加“开始”、“暂停”、“加速”三个额外功能。以下是代码实现：

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.util.ArrayList;
import java.util.List;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class SnakeGame extends JPanel implements ActionListener, KeyListener {
    private static final long serialVersionUID = 1L;
    private final int WIDTH = 500;
    private final int HEIGHT = 500;
    private final int DOT_SIZE = 10;
    private final int ALL_DOTS = 900;
    private final int RAND_POS = 29;
    private final int DELAY = 140;
    private final int SPEED_UP_DELAY = 70;
    private final int START_X = 100;
    private final int START_Y = 100;
    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 Timer timer;
    private boolean isPaused = false;
    private boolean isSpeedUp = false;

    public SnakeGame() {
        addKeyListener(this);
        setBackground(Color.black);
        setFocusable(true);
        setPreferredSize(new Dimension(WIDTH, HEIGHT));
        initGame();
    }

    private void initGame() {
        dots = 3;
        for (int z = 0; z < dots; z++) {
            x[z] = START_X - z * DOT_SIZE;
            y[z] = START_Y;
        }
        locateApple();
        timer = new Timer(DELAY, this);
        timer.start();
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        doDrawing(g);
    }

    private 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.fillRect(x[z], y[z], DOT_SIZE, DOT_SIZE);
            }
            g.setColor(Color.white);
            g.setFont(new Font("Arial", Font.BOLD, 18));
            g.drawString("Score: " + (dots - 3), 20, 25);
            if (isPaused) {
                g.setFont(new Font("Arial", Font.BOLD, 40));
                g.drawString("PAUSED", 170, 250);
            }
        } else {
            gameOver(g);
        }
    }

    private void gameOver(Graphics g) {
        g.setFont(new Font("Arial", Font.BOLD, 40));
        g.drawString("Game Over", 170, 250);
        g.setFont(new Font("Arial", Font.BOLD, 18));
        g.drawString("Score: " + (dots - 3), 20, 25);
    }

    private void checkApple() {
        if ((x[0] == apple_x) && (y[0] == apple_y)) {
            dots++;
            locateApple();
            if (isSpeedUp) {
                timer.setDelay(SPEED_UP_DELAY);
            }
        }
    }

    private 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;
        }
    }

    private 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();
        }
    }

    private 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;
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (!isPaused) {
            if (inGame) {
                checkApple();
                checkCollision();
                move();
            }
            repaint();
        }
    }

    @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;
        }
        if (key == KeyEvent.VK_SPACE) {
            isPaused = !isPaused;
        }
        if (key == KeyEvent.VK_SHIFT) {
            isSpeedUp = true;
            if (inGame) {
                timer.setDelay(SPEED_UP_DELAY);
            }
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        int key = e.getKeyCode();
        if (key == KeyEvent.VK_SHIFT) {
            isSpeedUp = false;
            if (inGame) {
                timer.setDelay(DELAY);
            }
        }
    }

    @Override
    public void keyTyped(KeyEvent e) {
    }

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

在这个实现中，我们添加了三个功能：

1. “开始”功能：在`initGame()`方法中，我们初始化了游戏，并在`Timer`对象上调用`start()`方法来启动游戏循环。在`main()`方法中，我们创建`JFrame`对象并将`SnakeGame`对象添加到其中，并将其设置为可见。

2. “暂停”功能：我们使用`isPaused`变量来跟踪游戏当前是否处于暂停状态。在`keyPressed()`方法中，我们检查用户是否按下空格键。如果是，我们将`isPaused`变量取反，以切换游戏状态。在`doDrawing()`方法中，如果游戏被暂停，我们将显示“PAUSED”消息。

3. “加速”功能：我们使用`isSpeedUp`变量来跟踪游戏当前是否处于加速状态。在`keyPressed()`方法中，我们检查用户是否按下Shift键。如果是，我们将`isSpeedUp`变量设置为true，并将`Timer`对象的延迟设置为`SPEED_UP_DELAY`。在`keyReleased()`方法中，我们将`isSpeedUp`变量设置为false，并将`Timer`对象的延迟设置为`DELAY`。

希望这可以帮助您实现Java贪吃蛇游戏，并添加“开始”、“暂停”、“加速”三个额外功能。