LunarLander and Snake 游戏更新线程总结

snake:是通过send和receive MSG方法来实现视图的跟新。invalidate（）
sudokuv：是也是通过invalidate跟新视图。由于没有自更新。所以视图变化发生在按键事件

jetboy:类似lunarlander
LunarLander:是通过线程在RUN方法中while(TRUE)中一直执行dodraw方法。其中它需要取得屏幕的canvas

1.extends view。这个方法所有的绘制都在onDraw()函数里进行，通过调用invalidate()通知系统调用onDraw()重绘屏幕，但是如果是在非UI线程中请求重绘就不一样了，具体怎么做大家自己去看看相关的东西。我没有看过，因为一般游戏开发我们会选择下一种方法。
2.extends SurfaceView,这是游戏开发最常用的方式，应该说如果你的游戏需要不停的更新图像，比如有帧动画的播放等等，那么就采用这种方式吧。
surfaceview的方式下你需要 implements SurfaceHolder.Callback
class SurfaceViewCore extends SurfaceView implements SurfaceHolder.Callback

LunarLander

class LunarView extends SurfaceView implements SurfaceHolder.Callback {       public LunarView(Context context, AttributeSet attrs) {        super(context, attrs);        // register our interest in hearing about changes to our surface        SurfaceHolder holder = getHolder();        holder.addCallback(this);        // create thread only; it's started in surfaceCreated()        thread = new LunarThread(holder, context, new Handler() {            @Override            public void handleMessage(Message m) {                mStatusText.setVisibility(m.getData().getInt("viz"));                mStatusText.setText(m.getData().getString("text"));            }        });        setFocusable(true); // make sure we get key events    }    @Override    public void onWindowFocusChanged(boolean hasWindowFocus) {        if (!hasWindowFocus) thread.pause();    }    public void surfaceCreated(SurfaceHolder holder) {        // start the thread here so that we don't busy-wait in run()        // waiting for the surface to be created        thread.setRunning(true);        thread.start();    }    public void surfaceDestroyed(SurfaceHolder holder) {        // we have to tell thread to shut down & wait for it to finish, or else        // it might touch the Surface after we return and explode        boolean retry = true;        thread.setRunning(false);        while (retry) {            try {                thread.join();                retry = false;            } catch (InterruptedException e) {            }        }    } class LunarThread extends Thread {             public LunarThread(SurfaceHolder surfaceHolder, Context context,                Handler handler) {            // get handles to some important objects            mSurfaceHolder = surfaceHolder;            mHandler = handler;            mContext = context;             }        public void run() {            while (mRun) {                Canvas c = null;                try {                    c = mSurfaceHolder.lockCanvas(null);                    synchronized (mSurfaceHolder) {                        if (mMode == STATE_RUNNING) updatePhysics();                        doDraw(c);                    }                } finally {                    // do this in a finally so that if an exception is thrown                    // during the above, we don't leave the Surface in an                    // inconsistent state                    if (c != null) {                        mSurfaceHolder.unlockCanvasAndPost(c);                    }                }            }        }        public void setState(int mode, CharSequence message) {            synchronized (mSurfaceHolder) {                mMode = mode;                if (mMode == STATE_RUNNING) {                    Message msg = mHandler.obtainMessage();                    Bundle b = new Bundle();                    b.putString("text", "");                    b.putInt("viz", View.INVISIBLE);                    msg.setData(b);                    mHandler.sendMessage(msg);                } else {                    if (message != null) {                        str = message + "\n" + str;                    }                    if (mMode == STATE_LOSE) mWinsInARow = 0;                    Message msg = mHandler.obtainMessage();                    Bundle b = new Bundle();                    b.putString("text", str.toString());                    b.putInt("viz", View.VISIBLE);                    msg.setData(b);                    mHandler.sendMessage(msg);                }            }        }        private void doDraw(Canvas canvas) {             }    }}

public class SnakeView extends TileView {    private static final Random RNG = new Random();    private RefreshHandler mRedrawHandler = new RefreshHandler();    class RefreshHandler extends Handler {        @Override        public void handleMessage(Message msg) {            SnakeView.this.update();            SnakeView.this.invalidate();        }        public void sleep(long delayMillis) {        this.removeMessages(0);            sendMessageDelayed(obtainMessage(0), delayMillis);        }    };    public SnakeView(Context context, AttributeSet attrs) {        super(context, attrs);        initSnakeView();   }    public SnakeView(Context context, AttributeSet attrs, int defStyle) {    super(context, attrs, defStyle);    initSnakeView();    }    private void initSnakeView() {        setFocusable(true);    }        private void initNewGame() {          }    public void update() {            mRedrawHandler.sleep(mMoveDelay);        }    }    }