经典贪吃蛇小游戏

一个名为贪吃蛇的小游戏，，，绝壁经典。。。

package Sea.study150227;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.util.*;
public class GreedSnake extends KeyAdapter{
	JFrame mainFrame;
	 
    Canvas paintCanvas;
 
    JLabel labelScore;// 计分牌
 
    SnakeModel snakeModel = null;// 蛇
 
    public static final int DEFAULT_WIDTH = 500;
 
    public static final int DEFAULT_HEIGHT = 300;
 
    public static final int nodeWidth = 10;
 
    public static final int nodeHeight = 10;
 
    // GreedSnake():初始化游戏界面
 
    public GreedSnake() {
 
        // 设置界面元素
        mainFrame = new JFrame("贪吃蛇游戏");
        Container cp = mainFrame.getContentPane();
        labelScore = new JLabel("所得分数为:", JLabel.CENTER);
        cp.add(labelScore, BorderLayout.NORTH);
        paintCanvas = new Canvas();
        paintCanvas.setSize(DEFAULT_WIDTH + 1, DEFAULT_HEIGHT + 1);
        paintCanvas.addKeyListener(this);
        cp.add(paintCanvas, BorderLayout.CENTER);
        JPanel panelButtom = new JPanel();
        panelButtom.setLayout(new BorderLayout());
        JLabel labelHelp;// 帮助信息
        labelHelp = new JLabel("按 PageUP 或 PageDown 键改变速度", JLabel.CENTER);
        panelButtom.add(labelHelp, BorderLayout.NORTH);
        labelHelp = new JLabel("按 Enter 或 S 键重新开始游戏", JLabel.CENTER);
        panelButtom.add(labelHelp, BorderLayout.CENTER);
        labelHelp = new JLabel("按 SPACE 键或 P 键暂停游戏", JLabel.CENTER);
        panelButtom.add(labelHelp, BorderLayout.SOUTH);
        cp.add(panelButtom, BorderLayout.SOUTH);
        mainFrame.addKeyListener(this);
        mainFrame.pack();
        mainFrame.setLocationRelativeTo(null);//设置窗体的居中
        mainFrame.setResizable(false);// 设置窗口大小不能变化
        mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        mainFrame.setVisible(true);
        begin();
    }
 
    // keyPressed():按键检测
 
    public void keyPressed(KeyEvent e) {
 
        int keyCode = e.getKeyCode();
        if (snakeModel.running)
            switch (keyCode) {
            case KeyEvent.VK_UP:
                snakeModel.changeDirection(SnakeModel.UP);
                break;
            case KeyEvent.VK_DOWN:
                snakeModel.changeDirection(SnakeModel.DOWN);
                break;
            case KeyEvent.VK_LEFT:
                snakeModel.changeDirection(SnakeModel.LEFT);
                break;
            case KeyEvent.VK_RIGHT:
                snakeModel.changeDirection(SnakeModel.RIGHT);
                break;
            case KeyEvent.VK_ADD:
            case KeyEvent.VK_PAGE_UP:
                snakeModel.speedUp();// 加速
                break;
            case KeyEvent.VK_SUBTRACT:
            case KeyEvent.VK_PAGE_DOWN:
                snakeModel.speedDown();// 减速
                break;
            case KeyEvent.VK_SPACE:
            case KeyEvent.VK_P:
                snakeModel.changePauseState();// 暂停或继续
                break;
            default:
            }
        // 重新开始
        if (keyCode == KeyEvent.VK_S || keyCode == KeyEvent.VK_ENTER) {
            snakeModel.running = false;
            begin();
        }
    }
 
    // repaint（）：绘制游戏界面（包括蛇和食物）
  void repaint() {
        Graphics g = paintCanvas.getGraphics();
        // draw background
        g.setColor(Color.LIGHT_GRAY);
        g.fillRect(0, 0, DEFAULT_WIDTH, DEFAULT_HEIGHT);
        // draw the snake
        g.setColor(Color.BLACK);
        LinkedList na = snakeModel.nodeArray;
        Iterator it = na.iterator();
        while (it.hasNext()) {
        	Node n = (Node) it.next();
            drawNode(g, n);
        }
        // draw the food
        g.setColor(Color.RED);
        Node n = snakeModel.food;
        drawNode(g, n);
        updateScore();
    }
 
    // drawNode（）：绘画某一结点（蛇身或食物）
 
    private void drawNode(Graphics g, Node n) {
        g.fillRect(n.x * nodeWidth, n.y * nodeHeight, nodeWidth - 1, nodeHeight - 1);
    }
 
    // updateScore（）：改变计分牌
 
    public void updateScore() {
        String s = "所得分数为: " + snakeModel.score;
        labelScore.setText(s);
    }
 
    // begin（）：游戏开始，放置贪吃蛇
 
    void begin() {
 
        if (snakeModel == null || !snakeModel.running) {
            snakeModel = new SnakeModel(this, DEFAULT_WIDTH / nodeWidth, DEFAULT_HEIGHT / nodeHeight);
            (new Thread(snakeModel)).start();
        }
    }
 
    // main（）：主函数
 
    public static void main(String[] args) {
 
        GreedSnake gs = new GreedSnake();
    }
}
 
// Node:结点类
 
class Node {
    int x;
 
    int y;
 
    Node(int x, int y) {
        this.x = x;
        this.y = y;
    }
}
 
// SnakeModel:贪吃蛇模型
 
class SnakeModel implements Runnable {
 
    GreedSnake gs;
 
    boolean[][] matrix;// 界面数据保存在数组里
 
    LinkedList nodeArray = new LinkedList();
 
    Node food;
 
    int maxX;// 最大宽度
 
    int maxY;// 最大长度
 
    int direction = 2;// 方向
 
    boolean running = false;
 
    int timeInterval = 200;// 间隔时间（速度）
 
    double speedChangeRate = 0.75;// 速度改变程度
 
    boolean paused = false;// 游戏状态
 
    int score = 0;
 
    int countMove = 0;
 
    // UP和DOWN是偶数，RIGHT和LEFT是奇数
    public static final int UP = 2;
 
    public static final int DOWN = 4;
 
    public static final int LEFT = 1;
 
    public static final int RIGHT = 3;
 
    // GreedModel():初始化界面
 public SnakeModel(GreedSnake gs, int maxX, int maxY) {
 
        this.gs = gs;
        this.maxX = maxX;
        this.maxY = maxY;
        matrix = new boolean[maxX][];
        for (int i = 0; i < maxX; ++i) {
            matrix[i] = new boolean[maxY];
            Arrays.fill(matrix[i], false);// 没有蛇和食物的地区置false
        }
        // 初始化贪吃蛇
        int initArrayLength = maxX > 20 ? 10 : maxX / 2;
        for (int i = 0; i < initArrayLength; ++i) {
            int x = maxX / 2 + i;
            int y = maxY / 2;
            nodeArray.addLast(new Node(x, y));
            matrix[x][y] = true;// 蛇身处置true
        }
        food = createFood();
        matrix[food.x][food.y] = true;// 食物处置true
    }
 
    // changeDirection():改变运动方向
 
    public void changeDirection(int newDirection) {
 
        if (direction % 2 != newDirection % 2) {// 避免冲突
            direction = newDirection;
        }
    }
 
    // moveOn():贪吃蛇运动函数
 
    public boolean moveOn() {
 
        Node n = (Node) nodeArray.getFirst();
        int x = n.x;
        int y = n.y;
        switch (direction) {
        case UP:
            y--;
            break;
        case DOWN:
            y++;
            break;
        case LEFT:
            x--;
            break;
        case RIGHT:
            x++;
            break;
        }
        if ((0 <= x && x < maxX) && (0 <= y && y < maxY)) {
 
            if (matrix[x][y]) {// 吃到食物或者撞到身体
 
                if (x == food.x && y == food.y) {// 吃到食物
 
                    nodeArray.addFirst(food);// 在头部加上一结点
                    // 计分规则与移动长度和速度有关
                    int scoreGet = (10000 - 200 * countMove) / timeInterval;
                    score += scoreGet > 0 ? scoreGet : 10;
                    countMove = 0;
                    food = createFood();
                    matrix[food.x][food.y] = true;
                    return true;
                } else
                    return false;// 撞到身体
            } else {// 什么都没有碰到
                nodeArray.addFirst(new Node(x, y));// 加上头部
                matrix[x][y] = true;
                n = (Node) nodeArray.removeLast();// 去掉尾部
                matrix[n.x][n.y] = false;
                countMove++;
                return true;
            }
        }
        return false;// 越界（撞到墙壁）
    }
 
    /* 发了一份贪吃蛇游戏的代码，谁能帮我解释一下，贪吃蛇程序的运行过程，运行步骤 */
    // run():贪吃蛇运动线程
  
 public void run() {
        running = true;
        while (running) {
            try {
                Thread.sleep(timeInterval);
            } catch (Exception e) {
                break;
            }
            if (!paused) {
 
                if (moveOn()) {// 未结束
                    gs.repaint();
                } else {// 游戏结束
                    JOptionPane.showMessageDialog(null, "GAME OVER", "Game Over", JOptionPane.INFORMATION_MESSAGE);
                    break;
                }
            }
        }
        running = false;
    }
 
    // createFood():生成食物及放置地点
 
    private Node createFood() {
 
        int x = 0;
        int y = 0;
        do {
            Random r = new Random();
            x = r.nextInt(maxX);
            y = r.nextInt(maxY);
        } while (matrix[x][y]);
        return new Node(x, y);
    }
 
    // speedUp():加快蛇运动速度
 
    public void speedUp() {
        timeInterval *= speedChangeRate;
    }
 
    // speedDown():放慢蛇运动速度
 
    public void speedDown() {
 
        timeInterval /= speedChangeRate;
    }
 
    // changePauseState(): 改变游戏状态（暂停或继续）
 
    public void changePauseState() {
 
        paused = !paused;
    }
}