Tutorial zum Schreiben kleiner Spiele in Java: No Snake Game

package cn.xeblog.snake.model;

import java.util.Objects;

/**
 * 坐标
 *
 * @author anlingyi
 * @date 2022/8/2 3:35 PM
 */
public class Point {

    public int x;

    public int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        Point point = (Point) o;
        return x == point.x && y == point.y;
    }

    @Override
    public int hashCode() {
        return Objects.hash(x, y);
    }

    @Override
    public String toString() {
        return "Point{" +
                "x=" + x +
                ", y=" + y +
                '}';
    }

}

package cn.xeblog.snake.model;

/**
 * @author anlingyi
 * @date 2022/8/2 5:25 PM
 */
public enum Direction {
    UP,
    DOWN,
    LEFT,
    RIGHT
}

package cn.xeblog.snake.model;

import java.util.List;

/**
 * 蛇
 *
 * @author anlingyi
 * @date 2022/8/2 3:32 PM
 */
public class Snake {

    public static int width = 10;

    public static int height = 10;

    /**
     * 蛇身坐标列表
     */
    public List<Point> body;

    public Snake(List<Point> body) {
        this.body = body;
    }

    /**
     * 添加蛇身坐标
     *
     * @param x
     * @param y
     */
    public void add(int x, int y) {
        this.body.add(new Point(x * width, y * height));
    }

    /**
     * 移除蛇尾坐标
     */
    public void removeLast() {
        int size = size();
        if (size == 0) {
            return;
        }

        this.body.remove(size - 1);
    }

    /**
     * 获取蛇头坐标
     *
     * @return
     */
    public Point getHead() {
        if (size() > 0) {
            return this.body.get(0);
        }

        return null;
    }

    /**
     * 获取蛇尾坐标
     *
     * @return
     */
    public Point getTail() {
        int size = size();
        if (size > 0) {
            return this.body.get(size - 1);
        }

        return null;
    }

    /**
     * 蛇身长度
     *
     * @return
     */
    public int size() {
        return this.body.size();
    }

    /**
     * 蛇移动
     *
     * @param direction 移动方向
     */
    public void move(Direction direction) {
        if (size() == 0) {
            return;
        }

        for (int i = this.size() - 1; i > 0; i--) {
            // 从蛇尾开始向前移动
            Point point = this.body.get(i);
            Point nextPoint = this.body.get(i - 1);
            point.x = nextPoint.x;
            point.y = nextPoint.y;
        }

        // 蛇头移动
        Point head = getHead();
        switch (direction) {
            case UP:
                head.y -= height;
                break;
            case DOWN:
                head.y += height;
                break;
            case LEFT:
                head.x -= width;
                break;
            case RIGHT:
                head.x += width;
                break;
        }
    }

}

package cn.xeblog.snake.model;

/**
 * 药丸
 *
 * @author anlingyi
 * @date 2022/8/2 4:49 PM
 */
public class Pill {

    public static int width = 10;

    public static int height = 10;

    /**
     * 坐标
     */
    public Point point;

    /**
     * 药丸类型
     */
    public PillType pillType;

    public enum PillType {
        /**
         * 红色药丸
         */
        RED(5),
        /**
         * 蓝色药丸
         */
        BLUE(2),
        /**
         * 绿色药丸
         */
        GREEN(1),
        ;

        /**
         * 分数
         */
        public int score;

        PillType(int score) {
            this.score = score;
        }
    }

    public Pill(int x, int y, PillType pillType) {
        this.point = new Point(x * width, y * height);
        this.pillType = pillType;
    }

}

package cn.xeblog.snake.ui;

import cn.xeblog.snake.model.Direction;
import cn.xeblog.snake.model.Pill;
import cn.xeblog.snake.model.Point;
import cn.xeblog.snake.model.Snake;

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Random;

/**
 * @author anlingyi
 * @date 2022/8/2 3:51 PM
 */
public class SnakeGameUI extends JPanel implements ActionListener {

    /**
     * 宽度
     */
    private int width;

    /**
     * 高度
     */
    private int height;


    /**
     * 蛇
     */
    private Snake snake;

    /**
     * 药丸
     */
    private Pill pill;

    /**
     * 移动方向
     */
    private Direction direction;

    /**
     * 停止游戏标记
     */
    private boolean stop;

    /**
     * 游戏状态 0.初始化 1.游戏胜利 2.游戏失败
     */
    private int state = -1;

    /**
     * 定时器
     */
    private Timer timer;

    /**
     * 移动速度
     */
    private int speed = 100;

    /**
     * 分数
     */
    private int score;

    /**
     * 特殊药丸列表
     */
    private ArrayList<Pill.PillType> specialPill;

    public SnakeGameUI(int width, int height) {
        this.width = width;
        this.height = height;
        this.timer = new Timer(speed, this);
        this.stop = true;

        initPanel();
    }

    /**
     * 初始化
     */
    private void init() {
        this.score = 0;
        this.state = 0;
        this.stop = true;
        this.timer.setDelay(speed);

        initSnake();
        initPill();
        generatePill();
        repaint();
    }

    /**
     * 初始化游戏面板
     */
    private void initPanel() {
        this.setPreferredSize(new Dimension(this.width, this.height));
        this.addKeyListener(new KeyAdapter() {
            @Override
            public void keyPressed(KeyEvent e) {
                if (stop && e.getKeyCode() != KeyEvent.VK_SPACE) {
                    return;
                }

                switch (e.getKeyCode()) {
                    case KeyEvent.VK_UP:
                        if (direction == Direction.DOWN) {
                            break;
                        }

                        direction = Direction.UP;
                        break;
                    case KeyEvent.VK_DOWN:
                        if (direction == Direction.UP) {
                            break;
                        }

                        direction = Direction.DOWN;
                        break;
                    case KeyEvent.VK_LEFT:
                        if (direction == Direction.RIGHT) {
                            break;
                        }

                        direction = Direction.LEFT;
                        break;
                    case KeyEvent.VK_RIGHT:
                        if (direction == Direction.LEFT) {
                            break;
                        }

                        direction = Direction.RIGHT;
                        break;
                    case KeyEvent.VK_SPACE:
                        if (state != 0) {
                            init();
                        }

                        stop = !stop;
                        if (!stop) {
                            timer.start();
                        }
                        break;
                }
            }
        });
    }

    /**
     * 初始化蛇
     */
    private void initSnake() {
        this.direction = Direction.LEFT;
        int maxX = this.width / Snake.width;
        int maxY = this.height / Snake.height;

        this.snake = new Snake(new ArrayList<>());
        this.snake.add(maxX - 2, 3);
        this.snake.add(maxX - 1, 3);
        this.snake.add(maxX - 1, 2);
        this.snake.add(maxX - 1, 1);
        for (int i = maxX - 1; i > 0; i--) {
            this.snake.add(i, 1);
        }
        for (int i = 1; i < maxY - 1; i++) {
            this.snake.add(1, i);
        }
        for (int i = 1; i < maxX - 1; i++) {
            this.snake.add(i, maxY - 2);
        }
    }

    /**
     * 初始化药丸
     */
    private void initPill() {
        this.specialPill = new ArrayList<>();
        for (int i = 0; i < 5; i++) {
            this.specialPill.add(Pill.PillType.RED);
        }
        for (int i = 0; i < 10; i++) {
            this.specialPill.add(Pill.PillType.BLUE);
        }

        Collections.shuffle(specialPill);
    }

    /**
     * 生成药丸
     */
    private void generatePill() {
        // 是否获取特殊药丸
        boolean getSpecialPill = new Random().nextInt(6) == 3;
        Pill.PillType pillType;
        if (getSpecialPill && this.specialPill.size() > 0) {
            // 生成特殊药丸
            int index = new Random().nextInt(this.specialPill.size());
            pillType = this.specialPill.get(index);
            this.specialPill.remove(index);
        } else {
            // 生成绿色药丸
            pillType = Pill.PillType.GREEN;
        }

        // 随机坐标
        int x = new Random().nextInt(this.width / Pill.width - 1);
        int y = new Random().nextInt(this.height / Pill.height - 1);
        this.pill = new Pill(x, y, pillType);
    }

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

        Graphics2D g2 = (Graphics2D) g;
        g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

        g2.setColor(new Color(66, 66, 66));
        g2.fillRect(0, 0, this.width, this.height);

        if (this.snake != null) {
            // 画蛇
            g2.setColor(new Color(255, 255, 255));
            for (int i = this.snake.size() - 1; i >= 0; i--) {
                Point point = this.snake.body.get(i);
                if (i == 0) {
                    // 蛇头
                    g2.setColor(new Color(255, 92, 92));
                } else {
                    g2.setColor(new Color(215, 173, 173));
                }

                g2.fillRect(point.x, point.y, Snake.width, Snake.height);
            }
        }

        if (this.pill != null) {
            // 画药丸
            Color pillColor;
            switch (this.pill.pillType) {
                case RED:
                    pillColor = new Color(255, 41, 41);
                    break;
                case BLUE:
                    pillColor = new Color(20, 250, 243);
                    break;
                default:
                    pillColor = new Color(97, 255, 113);
                    break;
            }

            g2.setColor(pillColor);
            g2.fillOval(pill.point.x, pill.point.y, Pill.width, Pill.height);
        }

        if (state > 0) {
            // 显示游戏结果
            String tips = "游戏失败！";
            if (state == 1) {
                tips = "游戏胜利！";
            }
            g2.setFont(new Font("", Font.BOLD, 20));
            g2.setColor(new Color(208, 74, 74));
            g2.drawString(tips, this.width / 3, this.height / 3);

            g2.setFont(new Font("", Font.PLAIN, 18));
            g2.setColor(Color.WHITE);
            g2.drawString("得分：" + this.score, this.width / 2, this.height / 3 + 50);
        }

        if (stop) {
            g2.setFont(new Font("", Font.PLAIN, 18));
            g2.setColor(Color.WHITE);
            g2.drawString("按空格键开始/暂停游戏！", this.width / 4, this.height - 50);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        // 是否吃药
        boolean isAte = false;
        if (!this.stop) {
            // 移动蛇
            this.snake.move(this.direction);
            Point head = this.snake.getHead();
            if (head.equals(this.pill.point)) {
                // 吃药了
                isAte = true;
                // 药丸分数
                int getScore = this.pill.pillType.score;
                // 累计分数
                this.score += getScore;
                for (int i = 0; i < getScore; i++) {
                    // 移除蛇尾
                    this.snake.removeLast();
                    if (this.snake.size() == 0) {
                        // 游戏胜利
                        this.state = 1;
                        this.stop = true;
                        break;
                    }
                }

                pill = null;
                if (this.score % 10 == 0) {
                    int curSpeed = this.timer.getDelay();
                    if (curSpeed > 30) {
                        // 加速
                        this.timer.setDelay(curSpeed - 10);
                    }
                }
            }

            if (state == 0) {
                // 判断蛇有没有咬到自己或是撞墙
                int maxWidth = this.width - this.snake.width;
                int maxHeight = this.height - this.snake.height;
                boolean isHitWall = head.x > maxWidth || head.x < 0 || head.y > maxHeight || head.y < 0;
                boolean isBiting = false;
                for (int i = this.snake.size() - 1; i > 0; i--) {
                    if (head.equals(this.snake.body.get(i))) {
                        isBiting = true;
                        break;
                    }
                }

                if (isHitWall || isBiting) {
                    // 游戏失败
                    this.state = 2;
                    this.stop = true;
                }
            }
        }

        if (this.stop) {
            this.timer.stop();
        } else if (isAte) {
            // 重新生成药丸
            generatePill();
        }

        repaint();
    }

}

package cn.xeblog.snake;

import cn.xeblog.snake.ui.SnakeGameUI;

import javax.swing.*;

/**
 * 启动游戏
 *
 * @author anlingyi
 * @date 2022/8/2 3:41 PM
 */
public class StartGame {

    public static void main(String[] args) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
        frame.setVisible(true);
        frame.setResizable(false);
        frame.setTitle("不贪吃蛇");
        frame.setSize(400, 320);
        frame.setLocationRelativeTo(null);
        JPanel gamePanel = new SnakeGameUI(400, 300);
        frame.add(gamePanel);
        gamePanel.requestFocus();
    }

}