Android：应用关闭30秒通知延迟显示并停止更新（在OnePlus 8T上）

Question

Google 有它的时钟应用程序，其中包括秒表。我目前正在尝试在我的应用程序中创建一个（递增）计时器，或者您可以将其称为秒表，它将能够在后台运行并且在运行进入时背景我希望它也显示一个通知，显示它计算的时间和一个“停止”按钮（所有这些都发生在 google 时钟应用程序（see here）中）。对于我的应用程序中的计时器，我使用了一个处理程序来发布一个 Runnable，它正在发布自己。我正在 Java.

中编写我的应用程序

定义'timer'（Handler 和 Runnable）的代码：

Handler timerHandler = new Handler();
Runnable timerRunnable = new Runnable() {
    @Override
    public void run() {
        long millis = System.currentTimeMillis() - startTime;
        seconds = (millis / 1000) + PrefUtil.getTimerSecondsPassed();
        timerHandler.postDelayed(this, 500);
    }
};

我的 onPause 函数：

@Override
public void onPause() {
    super.onPause();

    if (timerState == TimerState.Running) {
        timerHandler.removeCallbacks(timerRunnable);
        //TODO: start background timer, show notification
    }

    PrefUtil.setTimerSecondsPassed(seconds);
    PrefUtil.setTimerState(timerState);
}

如何在我的应用程序中实现后台服务和通知？

编辑

我已经成功地创建了一个运行我的计时器的前台服务，但是我有两个问题：

当我在大约 5 分钟后运行应用程序时，通知会延迟 10 秒显示。
通知在 starts/resumes 后约 30 秒后停止更新（计时器在后台保持运行ning，但通知不会随着计时器持续更新）。

这是我的 Service 代码：

public class TimerService extends Service {

    Long startTime = 0L, seconds = 0L;
    boolean notificationJustStarted = true;
    Handler timerHandler = new Handler();
    Runnable timerRunnable;
    NotificationCompat.Builder timerNotificationBuilder = new NotificationCompat.Builder(this, CHANNEL_ID);
    public static final String TIMER_BROADCAST_ID = "TimerBroadcast";
    Intent timerBroadcastIntent = new Intent(TIMER_BROADCAST_ID);

    @Override
    public void onCreate() {
        Log.d(TAG, "onCreate: started service");
        startForeground(1, new NotificationCompat.Builder(this, CHANNEL_ID).setSmallIcon(R.drawable.timer).setContentTitle("Goal In Progress").build());
        super.onCreate();
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        String goalName = intent.getStringExtra(PublicMethods.getAppContext().getString(R.string.timer_notification_service_current_goal_extra_name));
        startTime = System.currentTimeMillis();
        notificationJustStarted = true;
        timerRunnable = new Runnable() {
            @Override
            public void run() {
                long millis = System.currentTimeMillis() - startTime;
                seconds = (millis / 1000) + PrefUtil.getTimerSecondsPassed();
                updateNotification(goalName, seconds);
                timerHandler.postDelayed(this, 500);
            }
        };
        timerHandler.postDelayed(timerRunnable, 0);

        return START_STICKY;
    }

    public void updateNotification(String goalName, Long seconds) {
        try {
            if (notificationJustStarted) {
                Intent notificationIntent = new Intent(this, MainActivity.class);
                PendingIntent pendingIntent = PendingIntent.getActivity(this,
                        0, notificationIntent, PendingIntent.FLAG_IMMUTABLE);
                timerNotificationBuilder.setContentTitle("Goal In Progress")
                        .setOngoing(true)
                        .setSmallIcon(R.drawable.timer)
                        .setContentIntent(pendingIntent)
                        .setOnlyAlertOnce(true)
                        .setOngoing(true)
                        .setPriority(NotificationCompat.PRIORITY_MAX);
                notificationJustStarted = false;
            }

            timerNotificationBuilder.setContentText(goalName + " is in progress\nthis session's length: " + seconds);

            startForeground(1, timerNotificationBuilder.build());
        } catch (Exception e) {
            Log.d(TAG, "updateNotification: Couldn't display a notification, due to:");
            e.printStackTrace();
        }
    }

    @Override
    public void onDestroy() {
        timerHandler.removeCallbacks(timerRunnable);
        PrefUtil.setTimerSecondsPassed(seconds);
        super.onDestroy();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }
}

这是我在我的片段中开始它的方式：

private void startTimerService() {
        Intent serviceIntent = new Intent(getContext(), TimerService.class);
        serviceIntent.putExtra(getString(R.string.timer_notification_service_current_goal_extra_name), "*Current Goal Name Here*");
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            Objects.requireNonNull(getContext()).startForegroundService(serviceIntent);
        }
}

更新

当我在 google 像素模拟器上运行应用程序时，我没有遇到列出的任何问题

Answer 1

有两个问题。我会尝试解决这两个问题。

第一期

When I run the app after something like 5 minutes, the notification shows up in a 10-second delay.

为此，您需要使用代码更新通知。现在，因为显示需要时间，请在启动服务的 activity 中显示它，然后使用其构造函数将通知 ID 传递给服务。使用该 ID，在服务中更新它。

希望这能解决第一个问题。

第二期

the notification stops updating after around 30 seconds from the time it starts/resumes (The timer keeps running in the background, but the notification won't keep updating with the timer).

为了解决这个问题，您可以在 10 秒后通过它的 id 清除以前的通知。然后你可以为通知制作一个新的随机密钥（我更喜欢new Random().nextInt()）然后显示它。但是你或任何人都会说当通知来的时候声音太大了。只需在创建频道时以这种方式禁用它：

notificationChannel.setSound(null, null);

注意：您可能需要重新安装您的应用才能正常工作

如果这看起来很复杂，请看这个：

Runnable running -> When 10 seconds done from previous notification display -> Clear the notification -> Make a new notification id -> show notification with that id -> Repeat

编辑

这是我的工作代码：

import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.NotificationChannel;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.app.Service;
import android.content.Context;
import android.content.Intent;
import android.os.Handler;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.core.app.NotificationCompat;

import java.util.concurrent.TimeUnit;

public class TimerService extends Service {

    Long startTime = 0L, seconds = 0L;
    boolean notificationJustStarted = true;
    Handler timerHandler = new Handler();
    Runnable timerRunnable;
    private final String CHANNEL_ID = "Channel_id";
    NotificationManager mNotificationManager;

    NotificationCompat.Builder timerNotificationBuilder = new NotificationCompat.Builder(this, CHANNEL_ID).setContentTitle(CHANNEL_ID);

    @SuppressLint("InlinedApi")
    @Override
    public void onCreate() {
        super.onCreate();
        Toast.makeText(this, "created", Toast.LENGTH_SHORT).show();
        String TAG = "Timer Service";
        Log.d(TAG, "onCreate: started service");
        startForeground(1, new NotificationCompat.Builder(TimerService.this, createChannel()).setContentTitle("Goal In Progress").setPriority(NotificationManager.IMPORTANCE_MAX).build());
    }

    @Override
    public int onStartCommand(Intent intent, int flags, int startId) {
        String goalName = "Sample Goal";
        Toast.makeText(this, "started", Toast.LENGTH_SHORT).show();
        startTime = System.currentTimeMillis();
        notificationJustStarted = true;
        timerRunnable = new Runnable() {
            @Override
            public void run() {
                long millis = System.currentTimeMillis() - startTime;
                seconds = (millis / 1000) + PrefUtil.getTimerSecondsPassed(TimerService.this);
                updateNotification(goalName, seconds);
                Log.d("timerCount", seconds + "");
                timerHandler.postDelayed(this, 1000);
            }
        };
        timerHandler.postDelayed(timerRunnable, 0);

        return Service.START_STICKY;
    }

    @SuppressLint("NewApi")
    public void updateNotification(String goalName, long seconds) {
        if (notificationJustStarted) {
            Intent notificationIntent = new Intent(this, MainActivity.class);
            @SuppressLint("InlinedApi") PendingIntent pendingIntent = PendingIntent.getActivity(this,
                    0, notificationIntent, PendingIntent.FLAG_IMMUTABLE);
            timerNotificationBuilder.setContentTitle("Goal In Progress")
                    .setOngoing(true)
                    .setContentIntent(pendingIntent)
                    .setOnlyAlertOnce(true)
                    .setOngoing(true)
                    .setPriority(NotificationCompat.PRIORITY_MAX)
                    .setSmallIcon(R.drawable.ic_launcher_foreground);
            notificationJustStarted = false;
        }

        long minutes = TimeUnit.SECONDS.toMinutes(seconds);
        String time = minutes + ":" + (seconds - TimeUnit.MINUTES.toSeconds(minutes));

        timerNotificationBuilder.setContentText(goalName + " is in progress\nthis session's length: " + time);

        mNotificationManager.notify(1, timerNotificationBuilder.build());

        startForeground(1, timerNotificationBuilder.build());
    }

    @Override
    public void onDestroy() {
        timerHandler.removeCallbacks(timerRunnable);
        PrefUtil.setTimerSecondsPassed(this, seconds);
        super.onDestroy();
    }

    @Nullable
    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @NonNull
    @TargetApi(26)
    private synchronized String createChannel() {
        mNotificationManager = (NotificationManager) this.getSystemService(Context.NOTIFICATION_SERVICE);

        String name = "STOPWATCH";
        int importance = NotificationManager.IMPORTANCE_LOW;

        NotificationChannel mChannel = new NotificationChannel(CHANNEL_ID, name, importance);

        mChannel.setName("Notifications");

        if (mNotificationManager != null) {
            mNotificationManager.createNotificationChannel(mChannel);
        } else {
            stopSelf();
        }

        return CHANNEL_ID;
    }
}

您还可以在此 here 上查看我的存储库。这是一个完整的秒表应用

Answer 2

我找到通知在 30 秒后停止更新的原因了！显然，（根据）在某些设备运行 Android 高于9 的版本上有后台限制。

这些限制会阻止我的通知在应用程序关闭后 30 秒后更新，或者换句话说 - 从它们成为后台活动的那一刻起（即使它们是通过 startForeground()).

There is no way around this setting. You cannot programmatically disable it. Your only option is to programmatically check if it's enabled using ActivityManager.isBackgroundRestricted() and display a pop-up informing your users on how to disable this setting

从话题中接受的答案中说出用户。

这样，通知没有按预期更新的问题就解决了。虽然延迟显示第一个通知的问题仍未解决，但还有另一个问题 - 每次更新通知时，整个通知面板会冻结第二部分。

Android：应用关闭30秒通知延迟显示并停止更新（在OnePlus 8T上）

Android: Notification Shows in Delay And Stops Updating When App Closed for 30 Seconds (on OnePlus 8T)

java

notifications

android

stopwatch

background-service

编辑

更新

第一期

第二期

编辑