getWindow().setFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON, WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);

2.PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE); 
PowerManager.WakeLock wl = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK , "My Tag"); 
wl.acquire(); 
 // ..screen will stay on during this section.. 
wl.release(); 
两种方法