Android使用Thread加Handler實現計時與保持屏幕喚醒不熄滅

用到了兩個小知識點：一是使用Thread加Handler實現計時，二是控制屏幕喚醒不熄滅。

首先是計時，首先我使用單純的Handler來實現計時，代碼如下：

Handler handler = new Handler();
    Runnable runnable = new Runnable() {
        @Override
        public void run() {
            timeSec ++;
            mTimeCount.setText("" + timeSec);
            handler.postDelayed(this, 1000);
        }
    };

new Thread(new TimeThread()).start();

final Handler handler = new Handler() {

        public void handleMessage(Message msg) {
            switch (msg.what) {
                case 1:
                    timeSec++;
                    if (timeSec < 60) {  // 1分鐘以下情況
                        mTimeCount.setText("總耗時：" + timeSec + "秒");
                    } else if (timeSec < 3600) {  // 1小時以下情況
                        int minutes = timeSec / 60;
                        int second = timeSec % 60;
                        mTimeCount.setText("總耗時：" + minutes + "分" + second + "秒");
                    } else {
                        int hours = timeSec / 3600;
                        int minutes = (timeSec - hours * 3600) / 60;
                        int second = timeSec % 60;
                        mTimeCount.setText("總耗時：" + hours + "時" + minutes + "分" + second + "秒");
                    }

        }
        super.handleMessage(msg);
    }
};</pre>這樣UI在阻塞時，雖然我們的mTimeCount這個TextView沒有實時更新，但是計時函數還是在進行的，當UI線程的Thread.Sleep()結束時，就會更新。 <p><br />

</p>



下面看一下保持屏幕喚醒的邏輯： 


private static PowerManager.WakeLock wakeLock;
 




  public static void keepScreenOn(Context context, boolean on) {
        if (on) {
            PowerManager pm = (PowerManager) context.getSystemService(Context.POWER_SERVICE);
            wakeLock = pm.newWakeLock(PowerManager.SCREEN_BRIGHT_WAKE_LOCK | PowerManager.ON_AFTER_RELEASE, "==KeepScreenOn==");
            wakeLock.acquire();
        } else {
            if (wakeLock != null) {
                wakeLock.release();
                wakeLock = null;
            }
        }
    }


在應用destory的時候得把wakeLock給release掉： 




  @Override
    protected void onDestroy() {
        super.onDestroy();
        keepScreenOn(Main.this, false);
    }