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运行效果展示

功能实现

1. 程序框架：是利用IDEA的插件“JFormDesigner”来绘制的，里面的棋盘是一个JPanel
   
2. 蛇的功能是由链表实现的，我写的Snake类继承JLabel，Snake有个next的成员变量，表示蛇的某一块连接到的下一块。每次移动，就会从蛇尾开始逐一遍历一直到蛇的头部，将蛇的每一块都移动到下一块的位置上。
3. 蛇头的移动方向：Snake类里有一个direction静态成员变量，取值分别为EAST、WEST、NORTH、SOUTH，如果值为EAST，那么在每次移动，蛇头都会向右移动，其他同理。棋盘（JPanel）里添加了一个键盘监听事件，当键盘按下W或者↑，且当前的direction不为SOUTH时，就将direction的值改成NORTH。（这里的EAST、WEST、NORTH、SOUTH也不是什么枚举类型，只是一个int类型的值，是Snake里定义的常量）
4. 速度控制：使用Timer（定时调度）
5. 是否撞墙：直接判断蛇头的坐标有没有小于0或者大于棋盘的高度、宽度
6. 是否吃到食物：需要分情况讨论，如果蛇头坐标是(a,b)，食物坐标是(x,y)，每个格子的边长是size，如果当前direction为NORTH，当且仅当a == x && y == b + size时，成功吃到食物，其他同理。每次吃到食物，都会将这个食物作为这条蛇的头部，将原来的头部标识成蛇身，并重新随机生成一个食物（使用Random类随机生成一个坐标）
7. 是否自己撞自己：和是否吃到食物的判断方法一样

（可能有些地方写得不是很好，欢迎指正！）

代码

/* * Created by JFormDesigner on Sat Jun 27 23:11:31 CST 2020 *///Main.javapackage com.domain;import java.awt.*;import java.awt.event.*;import java.beans.*;import java.io.FileInputStream;import java.io.IOException;import java.util.Objects;import java.util.Properties;import javax.swing.*;import javax.swing.border.*;/** * @author 123 */public class Main extends JFrame {       public static Main main = null;    public static void main(String[] args) throws ClassNotFoundException, UnsupportedLookAndFeelException, InstantiationException, IllegalAccessException {           main = new Main();        Snake.width = main.game.getWidth();        Snake.height = main.game.getHeight();        //启动检查        if(Snake.width % Snake.size != 0 && Snake.height % Snake.size != 0){               JOptionPane.showMessageDialog(null,"未知错误！","",JOptionPane.ERROR_MESSAGE);            System.exit(-1);        }    }    public Main() throws ClassNotFoundException, UnsupportedLookAndFeelException, InstantiationException, IllegalAccessException {           String lookAndFeel = UIManager.getSystemLookAndFeelClassName();        UIManager.setLookAndFeel(lookAndFeel);        Font font = new Font("微软雅黑", Font.PLAIN, 14);        java.util.Enumeration keys = UIManager.getDefaults().keys();        while (keys.hasMoreElements()) {               Object key = keys.nextElement();            Object value = UIManager.get(key);            if (value instanceof javax.swing.plaf.FontUIResource)                UIManager.put(key, font);        }        setVisible(true);        setDefaultCloseOperation(EXIT_ON_CLOSE);        initComponents();        game.setFocusable(true);  //始终获得焦点        game.requestFocus(false);    }    private int lastChoose = 0;    private int speed = Snake.NORMAL_SPEED;    private void levelItemStateChanged(ItemEvent e) {           // TODO add your code here        if (e.getStateChange() == ItemEvent.SELECTED) {               if (Objects.equals(level.getSelectedItem(), "自定义")) {                   String s = null;                while (true) {                       s = JOptionPane.showInputDialog(null, "自定义速度（移动一次花费的时间）", speed);                    if (s == null) {                           level.setSelectedIndex(lastChoose);                        break;                    } else if (s.matches("\\d+") && Integer.parseInt(s) > 0) {                           speed = Integer.parseInt(s);                        break;                    }else{                           JOptionPane.showMessageDialog(null,"请输入大于0的数字！","",JOptionPane.ERROR_MESSAGE);                    }                }            } else {                   lastChoose = level.getSelectedIndex();            }        }    }    private void levelPropertyChange(PropertyChangeEvent e) {           // TODO add your code here    }    public JPanel getGame() {           return game;    }    public JButton getStart() {           return start;    }    public JLabel getNowScore() {           return nowScore;    }    public JLabel getMaxScore() {           return maxScore;    }    private void startActionPerformed(ActionEvent e) {           int speed = 0;        if(level.getSelectedIndex() == 0){               speed = Snake.NORMAL_SPEED;        }else if(level.getSelectedIndex() == 1){               speed = Snake.A_BIT_FAST_SPEED;        }else if(level.getSelectedIndex() == 2){               speed = Snake.FAST_SPEED;        }else if(level.getSelectedIndex() == 3){               speed = Snake.VERY_FAST_SPEED;        }else if(level.getSelectedIndex() == 4){               speed = Snake.A_BIT_SLOW_SPEED;        }else if(level.getSelectedIndex() == 5){               speed = Snake.SLOW_SPEED;        }else if(level.getSelectedIndex() == 6){               speed = Snake.VERY_SLOW_SPEED;        }else if(level.getSelectedIndex() == 7){               speed = this.speed;        }        // TODO add your code here        if(Snake.isStart){               if(Snake.isStop){                   Snake.toContinue();                start.setText("暂停");                Snake.isStop = false;            }else{                   Snake.stop();                start.setText("继续");                Snake.isStop = true;            }        }else{               Snake.start(speed);            start.setText("暂停");            Snake.isStart = true;            Snake.isStop = false;        }    }    private void gameKeyPressed(KeyEvent e) {           // TODO add your code here        int code = e.getKeyCode();        if(code == 37 || code == 65){               //左            if(Snake.direction != Snake.EAST){                   Snake.direction = Snake.WEST;            }        }else if(code == 38 || code==87){               //上            if(Snake.direction != Snake.SOUTH){                   Snake.direction = Snake.NORTH;            }        }else if(code == 39 || code==68){               //右            if(Snake.direction != Snake.WEST){                   Snake.direction = Snake.EAST;            }        }else if(code == 40 || code == 83){               //下            if(Snake.direction != Snake.NORTH){                   Snake.direction = Snake.SOUTH;            }        }    }    private void initComponents() {           // JFormDesigner - Component initialization - DO NOT MODIFY  //GEN-BEGIN:initComponents        control = new JPanel();        level = new JComboBox<>();        label1 = new JLabel();        start = new JButton();        label2 = new JLabel();        label3 = new JLabel();        nowScore = new JLabel();        maxScore = new JLabel();        game = new JPanel();        //======== this ========        setTitle("\u8d2a\u5403\u86c7");        setResizable(false);        setBackground(Color.black);        setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);        setForeground(new Color(0, 0, 2));        var contentPane = getContentPane();        contentPane.setLayout(null);        //======== control ========        {               control.setBorder(LineBorder.createBlackLineBorder());            control.setLayout(null);            //---- level ----            level.setModel(new DefaultComboBoxModel<>(new String[] {                   "\u6b63\u5e38\u901f\u5ea6",                "\u6709\u70b9\u5feb",                "\u5f88\u5feb",                "\u8d85\u7ea7\u5feb",                "\u6709\u70b9\u6162",                "\u5f88\u6162",                "\u8d85\u7ea7\u6162",                "\u81ea\u5b9a\u4e49"            }));            level.setFocusable(false);            level.addItemListener(e -> levelItemStateChanged(e));            level.addPropertyChangeListener(e -> levelPropertyChange(e));            control.add(level);            level.setBounds(85, 10, 115, level.getPreferredSize().height);            //---- label1 ----            label1.setText("\u9009\u62e9\u96be\u5ea6\uff1a");            label1.setFocusable(false);            control.add(label1);            label1.setBounds(new Rectangle(new Point(15, 12), label1.getPreferredSize()));            //---- start ----            start.setText("\u5f00\u59cb");            start.setFocusable(false);            start.addActionListener(e -> startActionPerformed(e));            control.add(start);            start.setBounds(210, 10, 90, start.getPreferredSize().height);            //---- label2 ----            label2.setText("\u5f53\u524d\u5f97\u5206\uff1a");            label2.setFocusable(false);            control.add(label2);            label2.setBounds(new Rectangle(new Point(430, 15), label2.getPreferredSize()));            //---- label3 ----            label3.setText("\u6700\u9ad8\u5f97\u5206\uff1a");            label3.setFocusable(false);            control.add(label3);            label3.setBounds(new Rectangle(new Point(560, 15), label3.getPreferredSize()));            //---- nowScore ----            nowScore.setText("0");            nowScore.setFont(new Font("\u5fae\u8f6f\u96c5\u9ed1", nowScore.getFont().getStyle() | Font.BOLD, nowScore.getFont().getSize() + 9));            nowScore.setForeground(new Color(0, 51, 255));            nowScore.setFocusable(false);            control.add(nowScore);            nowScore.setBounds(500, 10, 60, nowScore.getPreferredSize().height);            //---- maxScore ----            maxScore.setText("0");            maxScore.setFont(new Font("\u5fae\u8f6f\u96c5\u9ed1", maxScore.getFont().getStyle() | Font.BOLD, maxScore.getFont().getSize() + 9));            maxScore.setForeground(Color.red);            maxScore.setFocusable(false);            control.add(maxScore);            maxScore.setBounds(630, 10, 60, maxScore.getPreferredSize().height);        }        contentPane.add(control);        control.setBounds(10, 10, 700, 45);        //======== game ========        {               game.setBorder(LineBorder.createBlackLineBorder());            game.addKeyListener(new KeyAdapter() {                   @Override                public void keyPressed(KeyEvent e) {                       gameKeyPressed(e);                }            });            game.setLayout(null);        }        contentPane.add(game);        game.setBounds(10, 60, 700, 700);        contentPane.setPreferredSize(new Dimension(725, 770));        pack();        setLocationRelativeTo(getOwner());        // JFormDesigner - End of component initialization  //GEN-END:initComponents    }    // JFormDesigner - Variables declaration - DO NOT MODIFY  //GEN-BEGIN:variables    private JPanel control;    private JComboBox<String> level;    private JLabel label1;    private JButton start;    private JLabel label2;    private JLabel label3;    private JLabel nowScore;    private JLabel maxScore;    private JPanel game;// JFormDesigner - End of variables declaration  //GEN-END:variables}

//Snake.javapackage com.domain;import javax.swing.*;import java.awt.*;import java.util.Random;public class Snake extends JLabel {       public static final int NORMAL_SPEED = 25;    public static final int A_BIT_FAST_SPEED = 20;    public static final int FAST_SPEED = 15;    public static final int VERY_FAST_SPEED = 10;    public static final int A_BIT_SLOW_SPEED = 30;    public static final int SLOW_SPEED = 35;    public static final int VERY_SLOW_SPEED = 40;    //---------------------------------------------------------------------------    public static final Color BODY_COLOR = Color.YELLOW;    public static final Color FOOD_COLOR = Color.BLACK;    public static final Color HEAD_COLOR = Color.RED;    //--------------------------------------------------------------------------    public static final int NORTH = 0;    public static final int SOUTH = 1;    public static final int WEST = 2;    public static final int EAST = 3;    //---------------------------------------------------------------------------    public static boolean isStart = false;//是否已经开始游戏    public static boolean isStop = false;  //如果isStart为true，则isStop代表是不是在暂停    public static int width;  //游戏区域的宽度（在Main类中赋值）    public static int height; //高度    public static int nowScore = 0;  //当前分数    public static int maxScore = 0;  //最高分数    public static Snake food = null;  //食物    public static Snake head = null;  //头    public static Snake trail = null;  //尾    public static int speed = 30;   //移动速度    public static int size = 10;     //边长    public static int direction = EAST;  //移动方向    public static Timer timer = new Timer(speed, e -> action());  //定时调度    //---------------------------------------------------------------------------    public int x;    public int y;    public Snake next;    //----------------------------------------------------------------------------    public static Snake CREATE_FOOD() {           Snake snake = new Snake();        Random rd = new Random();        int x = rd.nextInt(width / size - 1) * size;        int y = rd.nextInt(height / size - 1) * size;        snake.x = x;        snake.y = y;        snake.setBackground(FOOD_COLOR);        Main.main.getGame().add(snake);        food = snake;        return snake;    }    public static Snake CREATE_HEAD() {           Snake snake = new Snake();        int x = (width / size - 1) / 2 * size;        int y = (height / size - 1) / 2 * size;        snake.x = x;        snake.y = y;        snake.setBackground(HEAD_COLOR);        Main.main.getGame().add(snake);        head = snake;        return snake;    }    public static Snake CREATE_BODY(Snake next) {           Snake snake = new Snake(next);        snake.setBackground(BODY_COLOR);        trail = snake;        Main.main.getGame().add(snake);        return snake;    }    //-----------------------------------------------------------------------------    /**     * 移动     */    public static void move() {           Snake temp = trail;        while (temp != head) {               temp.x = temp.next.x;            temp.y = temp.next.y;            temp = temp.next;        }        if (direction == EAST) {               //向右            head.x += size;        } else if (direction == WEST) {               //向左            head.x -= size;        } else if (direction == NORTH) {               head.y -= size;        } else if (direction == SOUTH) {               head.y += size;        }    }    //刷新    public static void flush() {           Snake temp = Snake.trail;        while (temp != null) {               temp.setBounds(temp.x, temp.y, size, size);            temp = temp.next;        }        if (food != null)            food.setBounds(food.x, food.y, size, size);        //重绘        Main.main.getGame().repaint();    }    //Timer执行一次    public static void action() {           move();        flush();        //判断是否吃到食物        if(isEatFood()){               ++nowScore;//加分            Main.main.getNowScore().setText(Integer.toString(nowScore));//更新分数到控件            //把现在的头的next变成食物            head.next = food;            head.setBackground(BODY_COLOR);            //食物变成新的head            head = food;            head.setBackground(HEAD_COLOR);            //创建新的食物            CREATE_FOOD();            return;        }        boolean isHitWall = isHitWall();        boolean isHitSelf = isHitSelf();        if (isHitWall || isHitSelf) {     //TODO 判断是否自己撞自己            if (isHitWall)                JOptionPane.showMessageDialog(null, "撞墙，游戏结束，得分为" + nowScore, "Game Over", JOptionPane.PLAIN_MESSAGE);            else{                   JOptionPane.showMessageDialog(null, "自己撞自己，游戏结束，得分为" + nowScore, "Game Over", JOptionPane.PLAIN_MESSAGE);            }            isStart = false;            Main.main.getStart().setText("重新开始");            if (nowScore > maxScore) {                   maxScore = nowScore;                Main.main.getMaxScore().setText(Integer.toString(maxScore));            }            timer.stop();        }    }    //开始游戏    public static void start(int speed) {           Main.main.getGame().removeAll();//清除所有组件        Main.main.getGame().repaint();//重绘        food = null;        head = null;        trail = null;        direction = EAST;        Snake s1 = CREATE_HEAD();        Snake s2 = CREATE_BODY(s1);        Snake s3 = CREATE_BODY(s2);        Snake s4 = CREATE_BODY(s3);        Snake s5 = CREATE_BODY(s4);        CREATE_FOOD();        flush();        //重置分数        nowScore = 0;        Main.main.getNowScore().setText("0");        Snake.speed = speed;        timer.setDelay(speed);        timer.start();    }    //暂停游戏    public static void stop() {           timer.stop();    }    //暂停后继续    public static void toContinue() {           timer.start();    }    //是否撞墙    public static boolean isHitWall() {           return head.x >= width || head.x < 0 || head.y >= height || head.y < 0;    }    //是否撞自己    public static boolean isHitSelf() {           Snake temp = trail;        try{               while (temp .next.next.next.next!= null && temp != head) {                   if (temp.x == head.x && temp.y == head.y)                    return true;                temp = temp.next;            }        }catch (NullPointerException e){               return false;        }        return false;    }    //判断是否吃到食物    public static boolean isEatFood(){           if (direction == EAST) {               //向右            return food.y == head.y && food.x == head.x + size;        } else if (direction == WEST) {               //向左            return food.y == head.y && food.x == head.x - size;        } else if (direction == NORTH) {               return food.x == head.x && food.y == head.y - size;        } else if (direction == SOUTH) {               return food.x == head.x && food.y == head.y + size;        }        return false;    }    //-----------------------------------------------------------------------------    Snake() {           super();        setPreferredSize(new Dimension(size, size));        setBackground(Color.black);        setOpaque(true);    }    Snake(Snake next) {           this();        if (direction == EAST) {               //向右            this.x = next.x - size;        } else if (direction == WEST) {               //向左            this.x = next.x + size;        } else if (direction == NORTH) {               this.y = next.y - size;        } else if (direction == SOUTH) {               this.y = next.y + size;        }        this.next = next;    }    //--------------------------------------------------------------------------}