Question

我每次发布新公告时都会发布通知。我从Firebase获取通知，因此我在onChildAdded()上调用通知功能。我收到了每个新公告的通知。但是，如果没有新的公告，即使在打开之后，最新公告也会偶尔重新出现。

通知类：公共类FirebaseBackgroundService扩展了服务{

private Firebase f = new Firebase("https://infotrack.firebaseio.com/infotrack/announcements");
Query queryAnnouncements = f.orderByChild("timeStamp").limitToLast(1);
Firebase ref = new Firebase("https://infotrack.firebaseio.com/guests");
Firebase userRef = ref.child("users/"+ref.getAuth().getUid()+"/notifications");

@Override
public IBinder onBind(Intent arg0) {
    return null;
}

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

            ChildEventListener handler = new ChildEventListener() {

        @Override
        public void onChildAdded(final DataSnapshot dataSnapshot, String s) {

            final AnnouncementsList announcement = dataSnapshot.getValue(AnnouncementsList.class);
            Log.e("announcements", dataSnapshot.getKey());

            userRef.addValueEventListener(new ValueEventListener() {
                @Override
                public void onDataChange(final DataSnapshot notifSnapshot) {
                    Log.e("check", notifSnapshot.getValue().toString());
                    if (notifSnapshot != null) {
                    Notifications notif = notifSnapshot.getValue(Notifications.class);
                        if(!dataSnapshot.getKey().equals(notif.getAnnouncements())){
                            buildNotif("Announcement", announcement.getBody(), "New announcement from Infotrack");
                            userRef.child("announcements").setValue(dataSnapshot.getKey());
                        }
                    }
                }

                @Override
                public void onCancelled(FirebaseError firebaseError) { }
            });

        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {}

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {}

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {}

        @Override
        public void onCancelled(FirebaseError firebaseError) {}

    };

    queryAnnouncements.addChildEventListener(handler);
}

private void buildNotif(String body){
    NotificationCompat.Builder builder = new NotificationCompat.Builder(this);

    builder.setContentTitle("New Announcement")
            .setContentText(body)
            .setSmallIcon(android.R.drawable.ic_dialog_info)
            .setAutoCancel(true)
            .setVibrate(new long[] { 1000, 500, 1000, 0, 1000 })
            .setOnlyAlertOnce(true);

    Intent intent = new Intent(this, Announcements.class);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK | Intent.FLAG_ACTIVITY_CLEAR_TASK);

    PendingIntent pendingIntent =
            PendingIntent.getActivity(
                    this,
                    0,
                    intent,
                    PendingIntent.FLAG_UPDATE_CURRENT
            );

    builder.setContentIntent(pendingIntent);

    NotificationManager mNotificationManager =
            (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);

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

}

}

广播接收器：

public class StartFirebaseAtBoot extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
    context.startService(new Intent(FirebaseBackgroundService.class.getName()));
}

}

Android Manifest：

<service
        android:name=".FirebaseBackgroundService"
        android:exported="false"
        android:process=":remote" >
    </service>

    <receiver android:name=".StartFirebaseAtBoot" android:enabled="true">
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED" />
        </intent-filter>
    </receiver>

这行我放在MainActivity的onCreate（）方法中： startService(new Intent(this, FirebaseBackgroundService.class));

堆栈跟踪：

    02-14 18:41:25.262 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/announcements: -KAUMTXlrOFvFaj20TNi
    02-14 18:41:25.282 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.372 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.382 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.802 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.812 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.902 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.902 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.942 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.942 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.962 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.972 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:25.992 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:25.992 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:26.012 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:26.032 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:26.042 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:26.052 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}
    02-14 18:41:26.122 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:26.132 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}
    02-14 18:41:26.152 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUM5H34QI-VklVRGSQ, news=1}

它一直持续到最后一行：

02-14 18:41:42.402 2446-2446/xyz.kimfeliciano.infotrack.infotrack:remote E/check: {announcements=-KAUMTXlrOFvFaj20TNi, news=1}

Answer 1

当应用连接到服务器时，Firebase会为该位置的每个现有孩子拨打onChildAdded()。因此，除非您删除子项，否则onChildAdded()调用的数量将继续增加。

您有两种选择：

在您向用户显示通知后将其从数据库中删除

public void onChildAdded(DataSnapshot snapshot, String previousChildKey) {
    AnnouncementsList announcement = snapshot.getValue(AnnouncementsList.class);
    buildNotif(announcement.getBody());
    snapshot.getRef().remove();
}

标记用户已看到的通知并跳过

大多数应用程序都使用第一个选项，因为它会自动缩短队列。

打开后，Android Notification会重新显示

1 个答案: