Android 简单实现贪吃蛇源码

android 简单实现贪吃蛇源码

一：实现原理
通过自定义view,然后根据小蛇的移动速度来不停的更新，绘制界面。

二：效果如下

三：核心实现
1：小蛇的位置是由很多点来绘制完成的，里面的点全部装在里面ArrayList里面。

”private ArrayList SpointList = new ArrayList<>();”

snakePoint 的代码如下

    class snakePoint {
        /**
         * 小蛇某个点x的位置
         */
        int x;
        /**
         * 小蛇某个y的位置
         */
        int y;

        snakePoint(int x, int y) {
            this.x = x;
            this.y = y;
        }
    }

2:在ondraw里面绘制出来这些点，区别蛇头和蛇尾

     for (int i = 0; i < SpointList.size(); i++) {
            snakePoint sp = SpointList.get(i);
            Rect rect_showPosition = new Rect(sp.x - snakeSize, sp.y - snakeSize, sp.x + snakeSize, sp.y + snakeSize);
            if(i==0){//蛇头
                canvas.drawBitmap(snake_head, rect, rect_showPosition, paint);
            }else{   //蛇尾
                canvas.drawBitmap(snake_body, rect, rect_showPosition, paint);
            }
        }

3：食物的绘制，通过随机的方法生成一个小与手机屏幕宽高的点，通过ondraw在绘制出来。

     /***
     * 随机添加食物
     */
    private void initFoot() {
        footPointList.clear();
        Random random = new Random();
        int fWide = GetFoodPosition(random.nextInt(ScreenWide));
        int fHeight = GetFoodPosition(random.nextInt(ScreenHeight));
        snakePoint sPoint = new snakePoint(fWide, fHeight);
        footPointList.add(sPoint);
    }

4：当小蛇移动的时候其实就是删除SpointList里面的最后一个点，在添加一个最新的点在SpointList为0 的位置，最新的位置依据小蛇移动的方向来做判断。然后在重新绘制就会给人感觉小蛇移动了一步的感觉。
当小蛇移动的那个点与食物的点坐标相同，即判断已经吃掉食物。这个时候的操作和小蛇移动的时候类似，但区别在于小蛇的数组SpointList不在删除最后一个，这样小蛇的长度就会增加。然后在重新绘制食物。

 private void StartGame() {
        int Rundistance = snakeSize * 2;//跑动的距离
        switch (nowDirection) {
            case 0://东
                if (!isLose(Rundistance)) {//判断时候吃掉了食物，撞墙等
                    snakePoint spoint = new snakePoint(SpointList.get(0).x + Rundistance, SpointList.get(0).y);
                    SpointList.add(0, spoint);
                } else {
                    return;
                }
                break;
            case 1://南
                if (!isLose(Rundistance)) {
                    snakePoint spoint_height = new snakePoint(SpointList.get(0).x, SpointList.get(0).y + Rundistance);
                    SpointList.add(0, spoint_height);
                } else {
                    return;
                }
                break;
            case 2://西
                if (!isLose(Rundistance)) {
                    snakePoint spoint_weath = new snakePoint(SpointList.get(0).x - Rundistance, SpointList.get(0).y);
                    SpointList.add(0, spoint_weath);
                } else {
                    return;
                }
                break;
            case 3://北
                if (!isLose(Rundistance)) {
                    snakePoint spoint_north = new snakePoint(SpointList.get(0).x, SpointList.get(0).y - Rundistance);
                    SpointList.add(0, spoint_north);
                } else {
                    return;
                }
                break;
        }
        invalidate();
        mRedrawHandler.sleep(SnakeSpeedDelay);

5：游戏结束，当小蛇撞墙或者碰着自己的时候就会结束游戏，小蛇碰着自己和小蛇吃食物的时候类似，判断前进的那个点是否包含在自己本身的SpointList里面，如果在表示小蛇碰撞了自己。至于边界，只需要判断小蛇前进的位置是否超过了手机屏幕的宽高就可以了。

   private boolean isLose(int Rundistance) {
        int snakeAfterPointx = 0;
        int snakeAfterPointy = 0;
        snakePoint snakePoint = SpointList.get(0);
        snakePoint footpoint = footPointList.get(0);

        if (footpoint.x == snakePoint.x && footpoint.y == snakePoint.y) {
            //吃掉了食物，需要重新初始化食物;
            score++;
            double DoubleSnakeSpeedDelay = SnakeSpeedDelay *0.9;
            SnakeSpeedDelay = (int) DoubleSnakeSpeedDelay;
            initFoot();//重新初始化
        } else {
                SpointList.remove(SpointList.size() - 1);//移除最后一个
        }
        switch (nowDirection) {
            case 0:
                snakeAfterPointx = SpointList.get(0).x + Rundistance;
                snakeAfterPointy = SpointList.get(0).y;
                if (SpointList.get(0).x + Rundistance >= ScreenWide) {
                    loseGame();
                    return true;
                }

                break;
            case 1:
                snakeAfterPointx = SpointList.get(0).x;
                snakeAfterPointy = SpointList.get(0).y + Rundistance;
                if (SpointList.get(0).y + Rundistance >= ScreenHeight) {
                    loseGame();
                    return true;
                }

                break;
            case 2:
                snakeAfterPointx = SpointList.get(0).x - Rundistance;
                snakeAfterPointy = SpointList.get(0).y;
                if (SpointList.get(0).x - Rundistance <= 0) {
                    loseGame();
                    return true;
                }
                break;
            case 3:
                snakeAfterPointx = SpointList.get(0).x;
                snakeAfterPointy = SpointList.get(0).y - Rundistance;
                if (SpointList.get(0).y - Rundistance <= 0) {
                    loseGame();
                    return true;
                }
                break;
        }
        snakePoint snakeAfterPoint = new snakePoint(snakeAfterPointx, snakeAfterPointy);
        if (snakeStrikeself(snakeAfterPoint)) { //判断是否会自撞
            loseGame();
            return true;
        }
        return false;
    }

以上简单的基本功能就实现了。