android - 倒数计时器在后台更新用户界面

Question

我有一个倒计时计时器，可以倒计时用户设置的当前时间。虽然，我希望能够访问其他应用程序，或者在运行倒计时计时器的同时转到设备的主屏幕，并继续使用倒计时剩余的计时器更新 TextView 。有什么办法吗？我尝试实现下面的服务，但我不知道这是否是完成此任务的正确方法，因为我确实收到了一个错误。

        @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_count_down);



//        if (savedInstanceState != null){
//
//        }

        titleTextView = (TextView)findViewById(R.id.titleTextView);
        timeTextView = (TextView)findViewById(R.id.timeTextView);


        Bundle getAlarmInfo = getIntent().getExtras();
        titleOfAlarm = getAlarmInfo.getString("Title");
        totalTime = getAlarmInfo.getString("totalTime");

         number = new BigDecimal(totalTime).toBigInteger();


        actualTimeFiniliazedInMilliSeconds = number.intValue();
        titleTextView.setText(titleOfAlarm);

//        countDown = new CountDownTimer(actualTimeFiniliazedInMilliSeconds, timeInterval);

//        new UpdateCountDownTime().execute();


        countDown = new CountDownTime(actualTimeFiniliazedInMilliSeconds, timeInterval);
        countDown.start();
//        startService(new Intent(getApplicationContext(), CountDown.class));

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_count_down, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }


    public class CountDownTime extends CountDownTimer {


        /**
         * @param millisInFuture    The number of millis in the future from the call
         *                          to {@link #start()} until the countdown is done and {@link #onFinish()}
         *                          is called.
         * @param countDownInterval The interval along the way to receive
         *                          {@link #onTick(long)} callbacks.
         */
        public CountDownTime(long millisInFuture, long countDownInterval) {
            super(millisInFuture, countDownInterval);
        }

        @Override
        public void onTick(long millisUntilFinished) {



            long millis = millisUntilFinished;
            hms = String.format("%02d:%02d:%02d", TimeUnit.MILLISECONDS.toHours(millis),
                    TimeUnit.MILLISECONDS.toMinutes(millis) - TimeUnit.HOURS.toMinutes(TimeUnit.MILLISECONDS.toHours(millis)),
                    TimeUnit.MILLISECONDS.toSeconds(millis) - TimeUnit.MINUTES.toSeconds(TimeUnit.MILLISECONDS.toMinutes(millis)));


            timeTextView.setText(hms);
        }

        @Override
        public void onFinish() {
            Intent goBack = new Intent(CountDownAct.this, ListOfAlarms.class);
        startActivity(goBack);
            finish();
        }




    }

    @Override
    protected void onPause() {
        super.onPause();
        timeTextView.setText(hms);





    }



//    public class CountDown extends Service{
//
//        public  CountDown () {
//
//        }
//
//        @Override
//        public IBinder onBind(Intent intent) {
//            return null;
//        }
//
//        @Override
//        public void onCreate() {
//            super.onCreate();
//
//            countDown = new CountDownTime(actualTimeFiniliazedInMilliSeconds, timeInterval);
//            countDown.start();
//        }
//    }

Answer 1

你需要使用 service 和 broadcast receiver 。我创建了一些 example for broadcast receiver给你。

检查一下，如果有问题请告诉我。

创建一个服务:TimerService.java

 @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        //Initialize and start the counter
        countDown = new HokusFocusCountDownTimer(timeDifference, 1000);

            countDown.start();

        return super.onStartCommand(intent, flags, startId);
    }

在 MainActivity.java 中

/*
    * This is used to receive the updated time from broadcast receiver
    * */
    private final BroadcastReceiver timeBroadCaster = new BroadcastReceiver() {
        @Override
        public void onReceive(Context context, Intent intent) {
            //method used to update your GUI fields
            updateGUI(intent);
        }
    };


    private void updateGUI(Intent intent) {

        AppLog.showLog("Update UI", "Timer Stopped");

        if (intent.getExtras() != null) {

            String focusHMS = intent.getStringExtra(Constants.HOCUS_FOCUS_TIMER);
            focusMilliSecond = intent.getLongExtra(Constants.HOCUS_FOCUS_TIMER_MILLI_SECOND, 0);
            txtFocusHourTimer.setText("" + focusHMS);
        }
    }


    @Override
    public void onResume() {
        super.onResume();
        registerReceiver(timeBroadCaster, new IntentFilter(
                HokusFocusCountDownTimer.COUNTDOWN_BROADCAST_RECEIVER));


    }

    @Override
    public void onPause() {
        super.onPause();
        try {
            unregisterReceiver(timeBroadCaster);
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

希望我的回答对你有所帮助