1小时后我怎样才能得到电池状态？

Question

我想要开发一个Android应用程序，它计算电池应用程序，所以我的想法是这样做:当用户启动应用程序时，应用程序获得手机的电池级别(例如: 80%)。1小时后，应用程序再次获得电池状态(例如: 76%)。计算:1小时内电池损失4%，电池寿命约20h (80/4)。

我知道，如何得到电池的状态，等等。我的问题是:如何在后台设置倒计时1小时？显示倒计时的地方不应该有任何textView。倒计时需要在后台进行。我怎么能这么做？

我在googled上搜索并发现了这一点，但这不起作用：(我将这些方法放在onCreate()中

CountDownTimer countDownTimer = new CountDownTimer(5000, 1000) {
        @Override
        public void onTick(long millisUntilFinished) {
            IntentFilter intFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
            BroadcastReceiver batteryLevelReceiver = new BroadcastReceiver() {
                @Override
                public void onReceive(Context context, Intent intent) {
                    int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
                }
            };
        }

        @Override
        public void onFinish() {
            BroadcastReceiver batteryLevelReceiver = new BroadcastReceiver() {
                @Override
                public void onReceive(Context context, Intent intent) {
                    int level = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
                    Toast toast = Toast.makeText(context, "Battery: " + level/4, Toast.LENGTH_LONG); // this is just, to check, if the countDown is still running
                    toast.show();
                }
            };
        }
    };

Answer 1

你需要注册一次你的广播接收器。

       //in Oncreate
       ...
       IntentFilter intFilter = new IntentFilter(Intent.ACTION_BATTERY_CHANGED);
       BatteryReceiver batteryReceiver = new BatteryReceiver();
       registerReceiver(batteryReceiver , intFilter);
       ...

       public class BatteryReceiver extends BroadcastReceiver {
            int startlevel = 0;
            long lastUpdateTime = 0;
            boolean isStartCheck = false;
            @Override
            public void onReceive(Context context, Intent intent) {
                if(!isStartCheck){
                    startlevel = intent.getIntExtra(BatteryManager.EXTRA_LEVEL, 0);
                    lastUpdateTime = System.currentTimeMillis();
                    isStartCheck = true;   
                } else {
                    if((System.currentTimeMillis() - lastUpdateTime)/1000 > 3600) {
                    // 1h was going. do your work.
                    reset();
                    }
                }  
            }

            public void reset() {
                lastUpdateTime = System.currentTimeMillis();
                isStartCheck = false;
                startLevel = 0;
            }

       }