android保持在休眠时，后台程序继续运行（让程序获取设备电源锁）

private PowerManager.WakeLock mWakeLock;

//申请设备电源锁
    private void acquireWakeLock()
    {
        if (null == mWakeLock)
        {
            PowerManager pm = (PowerManager)this.getSystemService(Context.POWER_SERVICE);
            mWakeLock = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK|PowerManager.ON_AFTER_RELEASE,"");
            if (null != mWakeLock)
            {
                mWakeLock.acquire();
            }
        }
    }

    //释放设备电源锁
    private void releaseWakeLock()
    {
        if (null != mWakeLock)
        {
            mWakeLock.release();
            mWakeLock = null;
        }
    }