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

    }

1. 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！