<Android 应用 之路> 简易贪吃蛇
最简单的贪吃蛇
最近想着忙里偷闲写点简单的Android应用，增加一些生活乐趣，由于平时工作主要精力并不是集中在书写apk上，更多的是解决代码问题和维护模块稳定，但是写代码本身是一件比较有趣的事情，因为这个过程是从无到有的。
名称：贪吃蛇
开发环境：IntelliJ IDEA 14.0.3
思路：
1. 定时刷新界面，因为蛇是不会停止的
2. 随机产生食物
3. 蛇体的更新
4. 蛇体如何出现移动的效果
缺陷：没有结束，没有碰壁，没有追尾，除非推出（现在知道为什么是最简单的了吧）
代码分析：
1. MyActivity， 主要作用就是定时刷新界面，让蛇不停的前进
private SnakeView mSnakeView; //填充窗口的View,刷新的对象
private static final int REFRESH = 1; //定义消息 防止硬编码
private static final int REFRESHINTERVAL = 300; //刷新的时间间隔
private boolean isPaused = false; //线程的停止标志位
private Handler mHandler = new Handler() { //thread handler 消息处理
@Override
public void handleMessage(Message msg) {
// TODO Auto-generated method stub
super.handleMessage(msg);
if(msg.arg1 == REFRESH) {
if(mSnakeView != null) {
mSnakeView.invalidate();
}
}
}
};
private Thread mRefreshThread; //用于发送刷新消息的线程
//Activity的onCreate方法
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mSnakeView = new SnakeView(this);
setContentView(mSnakeView);
isPaused = false;
mRefreshThread = new Thread("TimerThread"){
@Override
public void run() {
// TODO Auto-generated method stub
super.run();
while(!isPaused) {
Message msg = mHandler.obtainMessage();
msg.arg1 = REFRESH;
mHandler.sendMessage(msg);
try {
Thread.sleep(REFRESHINTERVAL); //休眠一段时间后再发送消息刷新界面
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
};
mRefreshThread.start(); //启动线程
}- SnakeView ，主游戏界面，蛇体，背景和食物的显示界面
//自定义View
public class SnakeView extends View{
public static final String TAG = "SnakeView";
private int mWidth; //view的宽
private int mHeight; //View的高
private static final int sXOffset = 0 ;
private static final int sYOffset = 0 ; // X坐标和Y坐标的偏移量，可以修改来缩小游戏范围
private final int BOXWIDTH = 30; //食物的边长，蛇体的宽度
private Random mRandom = new Random(); //用于产生随机数
private Point mFoodPosition; //食物的位置
private boolean mIsFoodDone = true; //食物是否已经被吃掉
private ArrayList<Point> mSnakeList; //蛇体可以看做是很多食物组成的
private Paint mSnakePaint; //用于画蛇的画笔
private int mSnakeDirection = 0; //蛇体运动的方向
private final int UP = 1;
private final int DOWN = 2;
private final int LEFT = 3;
private final int RIGHT =4;
private Paint mBgPaint;//游戏背景画笔
private Paint mFoodPaint;//食物画笔
public SnakeView(Context context) {
super(context);
// TODO Auto-generated constructor stub
mSnakeList = new ArrayList<Point>();
mSnakePaint = new Paint();
mSnakePaint.setColor(Color.RED);
mSnakePaint.setStyle(Paint.Style.FILL_AND_STROKE);
mSnakeList.add(new Point(500,500));
mSnakeList.add(new Point(500,530)); //初始化一条丑陋的蛇
mSnakeDirection = RIGHT;
mIsFoodDone = true;
mFoodPosition= new Point();
mFoodPaint = new Paint();
mFoodPaint.setColor(Color.CYAN);
mFoodPaint.setStyle(Paint.Style.FILL);
mBgPaint = new Paint();
Paint paint = new Paint();
paint.setColor(Color.WHITE); //初始化各种画笔
}
@Override
public boolean onTouchEvent(MotionEvent event) { //通过手势来改变蛇体运动方向
// TODO Auto-generated method stub
int x = (int)(event.getX());
int y = (int)(event.getY());
Log.e(TAG, "x =" + x + " y = " + y + " mSnakeDirection = " + mSnakeDirection);
if(mSnakeDirection == UP || mSnakeDirection == DOWN) {
if(x < head.x) mSnakeDirection = LEFT;
if(x > head.x) mSnakeDirection = RIGHT;
} else if(mSnakeDirection == LEFT || mSnakeDirection == RIGHT) {
if(y < head.y) mSnakeDirection = UP;
if(y > head.y) mSnakeDirection= DOWN;
}
//Log.e(TAG, "after adjust mSnakeDirection = " + mSnakeDirection);
return super.onTouchEvent(event);
}
@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
//Log.e(TAG ,"onDraw");
super.onDraw(canvas);
drawBg(canvas, mBgPaint); //画背景
drawFood(canvas, mFoodPaint);//画食物
drawSnake(canvas, mSnakePaint); //画蛇
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
// TODO Auto-generated method stub
super.onSizeChanged(w, h, oldw, oldh);
mWidth = w;
mHeight = h;
}
//画背景 这里通过sXOffset, sYOffset可以实现对蛇活动区域的限制
private void drawBg(Canvas canvas, Paint paint) {
canvas.drawColor(Color.WHITE);
//Rect rect = new Rect(sXOffset, sYOffset, mWidth - sXOffset, mHeight - sYOffset);
//canvas.drawRect(rect, paint);
}
//画蛇体
private void drawSnake(Canvas canvas, Paint paint) {
for(int i = 0 ; i < mSnakeList.size() ; i++ ) {
Point point = mSnakeList.get(i);
Rect rect = new Rect(point.x , point.y , point.x + BOXWIDTH , point.y + BOXWIDTH);
canvas.drawRect(rect, paint);
}
//蛇移动，更新list为下一次刷新做准备
snakeMove(mSnakeList, mSnakeDirection);
if(isFoodEaten()) { //如果吃了食物，长度加1
mIsFoodDone = true;
} else { //如果没有吃食物，由于前进时加了一个 这里删除尾巴，出现移动的效果
mSnakeList.remove(mSnakeList.size() - 1);
}
}
//画食物
private void drawFood(Canvas canvas, Paint paint) {
if(mIsFoodDone) { //只在前一个食物被吃掉的情况下才产生食物
mFoodPosition.x = mRandom.nextInt(mWidth - 2*sXOffset - BOXWIDTH) + sXOffset ;
mFoodPosition.y = mRandom.nextInt(mWidth - 2*sYOffset - BOXWIDTH) + sYOffset ;
mIsFoodDone = false;
}
Rect food = new Rect(mFoodPosition.x , mFoodPosition.y , mFoodPosition.x + BOXWIDTH , mFoodPosition.y + BOXWIDTH);
canvas.drawRect(food, paint);
}
public void snakeMove(ArrayList<Point> list , int direction) {
//Log.e(TAG," snakeMove ArrayList = " + list.toString());
Point orighead = list.get(0);
Point newhead = new Point();
//蛇前进，实现原理就是头加尾减，若吃到食物，头加尾不减
switch(direction) {
case UP:
newhead.x = orighead.x;
newhead.y = orighead.y - BOXWIDTH ;
break;
case DOWN:
newhead.x = orighead.x;
newhead.y = orighead.y + BOXWIDTH ;
break;
case LEFT:
newhead.x = orighead.x - BOXWIDTH;
newhead.y = orighead.y;
break;
case RIGHT:
newhead.x = orighead.x + BOXWIDTH ;
newhead.y = orighead.y;
break;
default:
break;
}
adjustHead(newhead);
list.add(0, newhead);
}
//边界判断
private boolean isOutBound(Point point) {
if(point.x < sXOffset || point.x > mWidth - sXOffset) return true;
if(point.y < sYOffset || point.y > mHeight - sYOffset) return true;
return false;
}
//出了边界，重新回来
private void adjustHead(Point point) {
//Log.e(TAG, "checkBound = " + isOutBound(point));
if(isOutBound(point)){
if(mSnakeDirection == UP) point.y = mHeight - sYOffset - BOXWIDTH;
if(mSnakeDirection == DOWN) point.y = sYOffset;
if(mSnakeDirection == LEFT) point.x = mWidth - sYOffset - BOXWIDTH;
if(mSnakeDirection == RIGHT) point.x = sXOffset;
}
}
//判断食物是否可以被吃
private boolean isFoodEaten() {
if(!mIsFoodDone) {
Rect foodrect = new Rect(mFoodPosition.x, mFoodPosition.y, mFoodPosition.x + BOXWIDTH, mFoodPosition.y + BOXWIDTH);
Point head = mSnakeList.get(0);
Rect headrect = new Rect(head.x, head.y, head.x + BOXWIDTH , head.y + BOXWIDTH);
return foodrect.intersect(headrect);
}
return false;
}
}效果展示：
(制作Gif有点不流畅实际效果很流畅)
代码附件：
http://download.csdn.net/detail/poorkick/9497370
欢迎讨论！
