android surfaceview 画图帧数控制

class drawbitmap_thread extends Thread{public void run(){while(true){long startTime = System.currentTimeMillis();                                                                //画图过程                                ................long endTime = System.currentTimeMillis(); int diffTime  = (int)(endTime - startTime);while(diffTime <= 30) {  diffTime = (int)(System.currentTimeMillis() - startTime);   Thread.yield();  }}}};