给出一个java版本贪吃蛇，重构前和重构后的代码，要求代码大于300行

好的，下面给出一个Java版本的贪吃蛇游戏的重构前和重构后的代码。这里使用了工厂模式和观察者模式来进行重构，以提高代码的可维护性和可扩展性。

重构前：

// SnakeGame.java
public class SnakeGame {
    private static final int WIDTH = 20;
    private static final int HEIGHT = 20;
    private int score = 0;
    private boolean gameOver = false;
    private Snake snake;
    private Apple apple;

    public SnakeGame() {
        snake = new Snake();
        apple = new Apple();
    }

    public void run() {
        while (!gameOver) {
            moveSnake();
            checkCollision();
            generateApple();
        }
        System.out.println("Game Over! Your score is " + score);
    }

    private void moveSnake() {
        snake.move();
    }

    private void checkCollision() {
        if (snake.collidesWith(apple)) {
            snake.grow();
            score++;
        } else if (snake.collidesWithSelf() || snake.hitsWall(WIDTH, HEIGHT)) {
            gameOver = true;
        }
    }

    private void generateApple() {
        if (apple.isEaten()) {
            apple = new Apple();
        }
    }
}

// Snake.java
public class Snake {
    private List<Point> body;
    private Point direction;

    public Snake() {
        body = new ArrayList<>();
        body.add(new Point(10, 10));
        direction = new Point(1, 0);
    }

    public void move() {
        Point head = body.get(0);
        Point newHead = new Point(head.x + direction.x, head.y + direction.y);
        body.add(0, newHead);
        body.remove(body.size() - 1);
    }

    public boolean collidesWith(Point point) {
        return body.contains(point);
    }

    public boolean collidesWithSelf() {
        Point head = body.get(0);
        for (int i = 1; i < body.size(); i++) {
            if (head.equals(body.get(i))) {
                return true;
            }
        }
        return false;
    }

    public boolean hitsWall(int width, int height) {
        Point head = body.get(0);
        return head.x < 0 || head.x >= width || head.y < 0 || head.y >= height;
    }

    public void grow() {
        Point head = body.get(0);
        Point newHead = new Point(head.x + direction.x, head.y + direction.y);
        body.add(0, newHead);
    }
}

// Apple.java
public class Apple {
    private Point position;
    private boolean isEaten;

    public Apple() {
        position = new Point((int) (Math.random() * 20), (int) (Math.random() * 20));
        isEaten = false;
    }

    public boolean isEaten() {
        return isEaten;
    }

    public void setEaten(boolean eaten) {
        isEaten = eaten;
    }

    public Point getPosition() {
        return position;
    }

    public void setPosition(Point position) {
        this.position = position;
    }
}

重构后：

// SnakeGame.java
public class SnakeGame {
    private static final int WIDTH = 20;
    private static final int HEIGHT = 20;
    private int score = 0;
    private boolean gameOver = false;
    private Snake snake;
    private Apple apple;

    public SnakeGame() {
        SnakeFactory snakeFactory = new SnakeFactory();
        snake = snakeFactory.createSnake();
        AppleFactory appleFactory = new AppleFactory();
        apple = appleFactory.createApple();
        snake.addObserver(apple);
    }

    public void run() {
        while (!gameOver) {
            moveSnake();
            checkCollision();
            generateApple();
        }
        System.out.println("Game Over! Your score is " + score);
    }

    private void moveSnake() {
        snake.move();
    }

    private void checkCollision() {
        if (snake.collidesWith(apple)) {
            snake.grow();
            score++;
            apple.setEaten(true);
        } else if (snake.collidesWithSelf() || snake.hitsWall(WIDTH, HEIGHT)) {
            gameOver = true;
        }
    }

    private void generateApple() {
        if (apple.isEaten()) {
            AppleFactory appleFactory = new AppleFactory();
            apple = appleFactory.createApple();
            snake.addObserver(apple);
        }
    }
}

// Snake.java
public class Snake extends Observable {
    private List<Point> body;
    private Point direction;

    public Snake() {
        body = new ArrayList<>();
        body.add(new Point(10, 10));
        direction = new Point(1, 0);
    }

    public void move() {
        Point head = body.get(0);
        Point newHead = new Point(head.x + direction.x, head.y + direction.y);
        body.add(0, newHead);
        body.remove(body.size() - 1);
        setChanged();
        notifyObservers();
    }

    public boolean collidesWith(Point point) {
        return body.contains(point);
    }

    public boolean collidesWithSelf() {
        Point head = body.get(0);
        for (int i = 1; i < body.size(); i++) {
            if (head.equals(body.get(i))) {
                return true;
            }
        }
        return false;
    }

    public boolean hitsWall(int width, int height) {
        Point head = body.get(0);
        return head.x < 0 || head.x >= width || head.y < 0 || head.y >= height;
    }

    public void grow() {
        Point head = body.get(0);
        Point newHead = new Point(head.x + direction.x, head.y + direction.y);
        body.add(0, newHead);
        setChanged();
        notifyObservers();
    }
}

// Apple.java
public class Apple implements Observer {
    private Point position;
    private boolean isEaten;

    public Apple() {
        position = new Point((int) (Math.random() * 20), (int) (Math.random() * 20));
        isEaten = false;
    }

    public boolean isEaten() {
        return isEaten;
    }

    public void setEaten(boolean eaten) {
        isEaten = eaten;
    }

    public Point getPosition() {
        return position;
    }

    public void setPosition(Point position) {
        this.position = position;
    }

    @Override
    public void update(Observable o, Object arg) {
        Snake snake = (Snake) o;
        setPosition(getRandomPosition());
        setEaten(false);
    }

    private Point getRandomPosition() {
        return new Point((int) (Math.random() * 20), (int) (Math.random() * 20));
    }
}

// SnakeFactory.java
public class SnakeFactory {
    public Snake createSnake() {
        return new Snake();
    }
}

// AppleFactory.java
public class AppleFactory {
    public Apple createApple() {
        return new Apple();
    }
}

重构后的代码将蛇和苹果分别封装成了类，使用工厂模式进行了创建，并使用观察者模式将蛇和苹果对象解耦，以便于扩展和维护。同时，新增了一些方法，如Snake类的Observable接口的方法和Apple类的update方法，来实现观察者模式。经过重构后，代码变得更加清晰、可维护、可扩展。