/**
* 程序名称：贪食蛇
* 原作者：BigF
* 修改者：algo
* 说明：我以前也用C写过这个程序，现在看到BigF用Java写的这个，发现虽然作者自称是Java的初学者，
* 但是明显编写程序的素养不错，程序结构写得很清晰，有些细微得地方也写得很简洁，一时兴起之
* 下，我认真解读了这个程序，发现数据和表现分开得很好，而我近日正在学习MVC设计模式，
* 因此尝试把程序得结构改了一下，用MVC模式来实现，对源程序得改动不多。
* 我同时也为程序增加了一些自己理解得注释，希望对大家阅读有帮助。
*/
public class GreedSnake {
public static void main(String[] args) {
SnakeModel model = new SnakeModel(20,30);
SnakeControl control = new SnakeControl(model);
SnakeView view = new SnakeView(model,control);
model.addObserver(view);
(new Thread(model)).start();
}
}
//----------------------------------------------------------------------
// SnakeModel.java
import javax.swing.*;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.Observable;
import java.util.Random;
/**
* 游戏的Model类，负责所有游戏相关数据及运行
*/
class SnakeModel extends Observable implements Runnable {
boolean[][] matrix; // 指示位置上有没蛇体或食物
LinkedList nodeArray = new LinkedList(); // 蛇体
Node food;
int maxX;
int maxY;
int direction = 2; // 蛇运行的方向
boolean running = false; // 运行状态
int timeInterval = 200; // 时间间隔，毫秒
double speedChangeRate = 0.75; // 每次得速度变化率
boolean paused = false; // 暂停标志
int score = 0; // 得分
int countMove = 0; // 吃到食物前移动的次数
// UP and DOWN should be even
// RIGHT and LEFT should be odd
public static final int UP = 2;
public static final int DOWN = 4;
public static final int LEFT = 1;
public static final int RIGHT = 3;
public SnakeModel( int maxX, int maxY) {
this.maxX = maxX;
this.maxY = maxY;
reset();
}
public void reset(){
direction = SnakeModel.UP; // 蛇运行的方向
timeInterval = 200; // 时间间隔，毫秒
paused = false; // 暂停标志
score = 0; // 得分
countMove = 0; // 吃到食物前移动的次数
// initial matirx, 全部清0
matrix = new boolean[maxX][];
for (int i = 0; i < maxX; ++i) {
matrix[i] = new boolean[maxY];
Arrays.fill(matrix[i], false);
}
// initial the snake
// 初始化蛇体，如果横向位置超过20个，长度为10，否则为横向位置的一半
int initArrayLength = maxX > 20 ? 10 : maxX / 2;
nodeArray.clear();
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;
}
// 创建食物
food = createFood();
matrix[food.x][food.y] = true;
}
public void changeDirection(int newDirection) {
// 改变的方向不能与原来方向同向或反向
if (direction % 2 != newDirection % 2) {
direction = newDirection;
}
}
/**
* 运行一次
* @return
*/
public boolean moveOn() {
Node n = (Node) nodeArray.getFirst();
int x = n.x;
int y = n.y;
// 根据方向增减坐标值
switch (direction) {
case UP:
y--;
break;
case DOWN:
y++;
break;
case LEFT:
x--;
break;
case RIGHT:
x++;
break;
}
// 如果新坐标落在有效范围内，则进行处理
if ((0 <= x && x < maxX) && (0 <= y && y < maxY)) {
if (matrix[x][y]) { // 如果新坐标的点上有东西（蛇体或者食物）
if (x == food.x && y == food.y) { // 吃到食物，成功
nodeArray.addFirst(food); // 从蛇头赠长
// 分数规则，与移动改变方向的次数和速度两个元素有关
int scoreGet = (10000 - 200 * countMove) / timeInterval;
score += scoreGet > 0 ? scoreGet : 10;
countMove = 0;
food = createFood(); // 创建新的食物
matrix[food.x][food.y] = true; // 设置食物所在位置
return true;
} else // 吃到蛇体自身，失败
return false;
} else { // 如果新坐标的点上没有东西（蛇体），移动蛇体
nodeArray.addFirst(new Node(x, y));
matrix[x][y] = true;
n = (Node) nodeArray.removeLast();
matrix[n.x][n.y] = false;
countMove++;
return true;
}
}
return false; // 触到边线，失败
}
public void run() {
running = true;
while (running) {
try {
Thread.sleep(timeInterval);
} catch (Exception e) {
break;
}
if (!paused) {
if (moveOn()) {
setChanged(); // Model通知View数据已经更新
notifyObservers();
} else {
JOptionPane.showMessageDialog(null,
"you failed",
"Game Over",
JOptionPane.INFORMATION_MESSAGE);
break;
}
}
}
running = false;
}
private Node createFood() {
int x = 0;
int y = 0;
// 随机获取一个有效区域内的与蛇体和食物不重叠的位置
do {
Random r = new Random();
x = r.nextInt(maxX);
y = r.nextInt(maxY);
} while (matrix[x][y]);
return new Node(x, y);
}
public void speedUp() {
timeInterval *= speedChangeRate;
}
public void speedDown() {
timeInterval /= speedChangeRate;
}
public void changePauseState() {
paused = !paused;
}
public String toString() {
String result = "";
for (int i = 0; i < nodeArray.size(); ++i) {
Node n = (Node) nodeArray.get(i);
result += "[" + n.x + "," + n.y + "]";
}
return result;
}
}
class Node {
int x;
int y;
Node(int x, int y) {
this.x = x;
this.y = y;
}
}
//---------------------------------------------------------------------
// SnakeControl.java
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
/**
* MVC中的Controler，负责接收用户的操作，并把用户操作通知Model
*/
public class SnakeControl implements KeyListener{
SnakeModel model;
public SnakeControl(SnakeModel model){
this.model = model;
}
public void keyPressed(KeyEvent e) {
int keyCode = e.getKeyCode();
if (model.running){ // 运行状态下，处理的按键
switch (keyCode) {
case KeyEvent.VK_UP:
model.changeDirection(SnakeModel.UP);
break;
case KeyEvent.VK_DOWN:
model.changeDirection(SnakeModel.DOWN);
break;
case KeyEvent.VK_LEFT:
model.changeDirection(SnakeModel.LEFT);
break;
case KeyEvent.VK_RIGHT:
model.changeDirection(SnakeModel.RIGHT);
break;
case KeyEvent.VK_ADD:
case KeyEvent.VK_PAGE_UP:
model.speedUp();
break;
case KeyEvent.VK_SUBTRACT:
case KeyEvent.VK_PAGE_DOWN:
model.speedDown();
break;
case KeyEvent.VK_SPACE:
case KeyEvent.VK_P:
model.changePauseState();
break;
default:
}
}
// 任何情况下处理的按键，按键导致重新启动游戏
if (keyCode == KeyEvent.VK_R ||
keyCode == KeyEvent.VK_S ||
keyCode == KeyEvent.VK_ENTER) {
model.reset();
}
}
public void keyReleased(KeyEvent e) {
}
public void keyTyped(KeyEvent e) {
}
}
//----------------------------------------------------------------------
// SnakeView.java
import javax.swing.*;
import java.awt.*;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Observable;
import java.util.Observer;
/**
* MVC模式中得Viewer，只负责对数据的显示,而不用理会游戏的控制逻辑
*/
public class SnakeView implements Observer {
SnakeControl control = null;
SnakeModel model = null;
JFrame mainFrame;
Canvas paintCanvas;
JLabel labelScore;
public static final int canvasWidth = 200;
public static final int canvasHeight = 300;
public static final int nodeWidth = 10;
public static final int nodeHeight = 10;
public SnakeView(SnakeModel model, SnakeControl control) {
this.model = model;
this.control = control;
mainFrame = new JFrame("GreedSnake");
Container cp = mainFrame.getContentPane();
// 创建顶部的分数显示
labelScore = new JLabel("Score:");
cp.add(labelScore, BorderLayout.NORTH);
// 创建中间的游戏显示区域
paintCanvas = new Canvas();
paintCanvas.setSize(canvasWidth + 1, canvasHeight + 1);
paintCanvas.addKeyListener(control);
cp.add(paintCanvas, BorderLayout.CENTER);
// 创建底下的帮助栏
JPanel panelButtom = new JPanel();
panelButtom.setLayout(new BorderLayout());
JLabel labelHelp;
labelHelp = new JLabel("PageUp, PageDown for speed;", JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.NORTH);
labelHelp = new JLabel("ENTER or R or S for start;", JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.CENTER);
labelHelp = new JLabel("SPACE or P for pause", JLabel.CENTER);
panelButtom.add(labelHelp, BorderLayout.SOUTH);
cp.add(panelButtom, BorderLayout.SOUTH);
mainFrame.addKeyListener(control);
mainFrame.pack();
mainFrame.setResizable(false);
mainFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mainFrame.setVisible(true);
}
void repaint() {
Graphics g = paintCanvas.getGraphics();
//draw background
g.setColor(Color.WHITE);
g.fillRect(0, 0, canvasWidth, canvasHeight);
// draw the snake
g.setColor(Color.BLACK);
LinkedList na = model.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 = model.food;
drawNode(g, n);
updateScore();
}
private void drawNode(Graphics g, Node n) {
g.fillRect(n.x * nodeWidth,
n.y * nodeHeight,
nodeWidth - 1,
nodeHeight - 1);
}
public void updateScore() {
String s = "Score: " + model.score;
labelScore.setText(s);
}
public void update(Observable o, Object arg) {
repaint();
}
}
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