如何以编程方式关闭android手机的屏幕？

Question

如何以编程方式关闭Android手机的屏幕？我尝试使用以下代码，没有运气

PowerManager mPowerManager = (PowerManager) getSystemService(POWER_SERVICE);
mWakeLock = mPowerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MYTAG");

mWakeLock.acquire();