给我实现一个贪吃蛇的游戏，用java语言实现，要求：背景色为黑色，幕布为700*700，蛇在幕布中心位置出生，蛇的颜色为黄色，在地图上随机生成红色的小球，蛇吃到球会变长，当蛇撞到自己的身体或幕布边界，游戏结束

好的，我会给你提供一个简单的贪吃蛇游戏的Java代码，满足你的要求。代码如下：

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.ArrayList;
import java.util.List;
import java.util.Random;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class SnakeGame extends JPanel implements KeyListener, Runnable {
    private static final long serialVersionUID = 1L;

    private static final int WIDTH = 700;
    private static final int HEIGHT = 700;

    private static final int DOT_SIZE = 10;

    private static final int INITIAL_SNAKE_LENGTH = 5;
    private static final int INITIAL_SNAKE_X = WIDTH / 2;
    private static final int INITIAL_SNAKE_Y = HEIGHT / 2;

    private static final int DELAY = 100;

    private static final Color BACKGROUND_COLOR = Color.BLACK;
    private static final Color SNAKE_COLOR = Color.YELLOW;
    private static final Color FOOD_COLOR = Color.RED;

    private static final int SCORE_X = 10;
    private static final int SCORE_Y = 20;

    private static final Random RANDOM = new Random();

    private List<Point> snake;
    private Point food;
    private int score;

    private boolean movingLeft;
    private boolean movingRight;
    private boolean movingUp;
    private boolean movingDown;

    private boolean gameOver;

    public SnakeGame() {
        setPreferredSize(new java.awt.Dimension(WIDTH, HEIGHT));
        setBackground(BACKGROUND_COLOR);
        setFocusable(true);

        addKeyListener(this);

        snake = new ArrayList<Point>();
        for (int i = 0; i < INITIAL_SNAKE_LENGTH; i++) {
            snake.add(new Point(INITIAL_SNAKE_X - i * DOT_SIZE, INITIAL_SNAKE_Y));
        }

        food = new Point(RANDOM.nextInt(WIDTH / DOT_SIZE) * DOT_SIZE, RANDOM.nextInt(HEIGHT / DOT_SIZE) * DOT_SIZE);

        score = 0;

        movingLeft = false;
        movingRight = true;
        movingUp = false;
        movingDown = false;

        gameOver = false;
    }

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

        if (gameOver) {
            g.setColor(Color.WHITE);
            g.drawString("Game Over!", WIDTH / 2 - 30, HEIGHT / 2);
        } else {
            g.setColor(SNAKE_COLOR);
            for (Point p : snake) {
                g.fillRect(p.x, p.y, DOT_SIZE, DOT_SIZE);
            }

            g.setColor(FOOD_COLOR);
            g.fillRect(food.x, food.y, DOT_SIZE, DOT_SIZE);

            g.setColor(Color.WHITE);
            g.drawString("Score: " + score, SCORE_X, SCORE_Y);
        }
    }

    @Override
    public void run() {
        while (!gameOver) {
            move();
            checkCollision();
            repaint();
            sleep();
        }
    }

    private void move() {
        int dx = 0;
        int dy = 0;

        if (movingLeft) {
            dx = -DOT_SIZE;
        } else if (movingRight) {
            dx = DOT_SIZE;
        } else if (movingUp) {
            dy = -DOT_SIZE;
        } else if (movingDown) {
            dy = DOT_SIZE;
        }

        int newX = snake.get(0).x + dx;
        int newY = snake.get(0).y + dy;

        snake.add(0, new Point(newX, newY));
        snake.remove(snake.size() - 1);
    }

    private void checkCollision() {
        if (snake.get(0).equals(food)) {
            score++;
            snake.add(new Point(food));
            food.setLocation(RANDOM.nextInt(WIDTH / DOT_SIZE) * DOT_SIZE, RANDOM.nextInt(HEIGHT / DOT_SIZE) * DOT_SIZE);
        }

        if (snake.get(0).x < 0 || snake.get(0).x >= WIDTH || snake.get(0).y < 0 || snake.get(0).y >= HEIGHT) {
            gameOver = true;
        }

        for (int i = 1; i < snake.size(); i++) {
            if (snake.get(0).equals(snake.get(i))) {
                gameOver = true;
                break;
            }
        }
    }

    private void sleep() {
        try {
            Thread.sleep(DELAY);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

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

        if (key == KeyEvent.VK_LEFT && !movingRight) {
            movingLeft = true;
            movingRight = false;
            movingUp = false;
            movingDown = false;
        } else if (key == KeyEvent.VK_RIGHT && !movingLeft) {
            movingLeft = false;
            movingRight = true;
            movingUp = false;
            movingDown = false;
        } else if (key == KeyEvent.VK_UP && !movingDown) {
            movingLeft = false;
            movingRight = false;
            movingUp = true;
            movingDown = false;
        } else if (key == KeyEvent.VK_DOWN && !movingUp) {
            movingLeft = false;
            movingRight = false;
            movingUp = false;
            movingDown = true;
        }
    }

    @Override
    public void keyReleased(KeyEvent e) {
        // do nothing
    }

    @Override
    public void keyTyped(KeyEvent e) {
        // do nothing
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Snake Game");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        SnakeGame game = new SnakeGame();
        frame.getContentPane().add(game);

        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);

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

你可以将这段代码复制到你的IDE（例如Eclipse）中，然后运行它。这个程序有一些简单的图形界面，其中包含了贪吃蛇的游戏，并且满足你的要求。希望这个程序能够帮助到你！