android - Flutter 工作管理器返回 "Worker result FAILURE for Work [ id=XXXXXxXXXXxXXXX tags={ be.tramckrijte.workmanager.BackgroundWorker } ]"

Question

我正在构建一个通知用户祈祷时间的应用程序。我正在使用 adhan 包来计算时间并将其保存在共享首选项中。由于祈祷时间每 24 小时更改一次，因此我使用 workmanager 获取该特定时间的祈祷时间，并每 20 小时将其保存在共享偏好中。但是我正面临这个问题，有没有其他或更好的方法可以实现这一目标。

Launching lib/main.dart on ASUS X00T in debug mode...
✓ Built build/app/outputs/flutter-apk/app-debug.apk.
Connecting to VM Service at ws://127.0.0.1:44753/d5gE32RyvC4=/ws
I/.example.notif(14281): Waiting for a blocking GC ProfileSaver
E/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: Invalid argument(s) (input): Must not be null
[38;5;244mE/flutter (14281): #0      _RegExp.firstMatch (dart:core-patch/regexp_patch.dart:221:24)[39;49m
[38;5;244mE/flutter (14281): #1      DateTime.parse (dart:core/date_time.dart:266:23)[39;49m
[38;5;248mE/flutter (14281): #2      PrayerTime.getFajr[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;248mE/flutter (14281): #3      _GetPrayersPageState.loalData[39;49m
E/flutter (14281): <asynchronous suspension>
E/flutter (14281):
E/cutils-trace(14281): Error opening trace file: No such file or directory (2)
I/flutter (14281): getAndSavePrayerscallbackDispatcher
I/flutter (14281): 2021-03-25 13:07:32.419749+0530
I/flutter (14281): 2021-03-25 12:45:00.000+0530
I/flutter (14281): 2021-03-25 20:04:00.000+0530
I/flutter (14281): 2021-03-25 17:08:00.000+0530
I/flutter (14281): 2021-03-25 20:04:00.000+0530
E/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The method 'zonedSchedule' was called on null.
E/flutter (14281): Receiver: null
E/flutter (14281): Tried calling: zonedSchedule(0, "Title", "Body", Instance of 'TZDateTime', Instance of 'NotificationDetails', androidAllowWhileIdle: true, uiLocalNotificationDateInterpretation: Instance of 'UILocalNotificationDateInterpretation')
[38;5;244mE/flutter (14281): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)[39;49m
[38;5;248mE/flutter (14281): #1      NotificationManager.zonedNotification.<anonymous closure>[39;49m
[38;5;248mE/flutter (14281): #2      NotificationManager.zonedNotification.<anonymous closure>[39;49m
[38;5;244mE/flutter (14281): #3      List.forEach (dart:core-patch/growable_array.dart:403:8)[39;49m
[38;5;248mE/flutter (14281): #4      NotificationManager.zonedNotification[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;248mE/flutter (14281): #5      callbackDispatcher.<anonymous closure>[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;244mE/flutter (14281): #6      MethodChannel._handleAsMethodCall[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;244mE/flutter (14281): #7      _DefaultBinaryMessenger.handlePlatformMessage[39;49m
E/flutter (14281): <asynchronous suspension>
E/flutter (14281):
I/chatty  (14281): uid=10412(com.example.notify) 2.ui identical 3 lines
E/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The method 'zonedSchedule' was called on null.
E/flutter (14281): Receiver: null
E/flutter (14281): Tried calling: zonedSchedule(0, "Title", "Body", Instance of 'TZDateTime', Instance of 'NotificationDetails', androidAllowWhileIdle: true, uiLocalNotificationDateInterpretation: Instance of 'UILocalNotificationDateInterpretation')
[38;5;244mE/flutter (14281): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)[39;49m
[38;5;248mE/flutter (14281): #1      NotificationManager.zonedNotification.<anonymous closure>[39;49m
[38;5;248mE/flutter (14281): #2      NotificationManager.zonedNotification.<anonymous closure>[39;49m
[38;5;244mE/flutter (14281): #3      List.forEach (dart:core-patch/growable_array.dart:403:8)[39;49m
[38;5;248mE/flutter (14281): #4      NotificationManager.zonedNotification[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;248mE/flutter (14281): #5      callbackDispatcher.<anonymous closure>[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;244mE/flutter (14281): #6      MethodChannel._handleAsMethodCall[39;49m
E/flutter (14281): <asynchronous suspension>
[38;5;244mE/flutter (14281): #7      _DefaultBinaryMessenger.handlePlatformMessage[39;49m
E/flutter (14281): <asynchronous suspension>
E/flutter (14281):
I/WM-WorkerWrapper(14281): Worker result FAILURE for Work [ id=0a8091e2-1677-4fc9-9fbd-79468e004d97, tags={ be.tramckrijte.workmanager.BackgroundWorker } ]

main.dart

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:notify/local_notification/manage_notification.dart';
import 'package:notify/prayer_times.dart';
import 'package:workmanager/workmanager.dart';
import 'package:timezone/timezone.dart' as tz;

const String uniqueName = "getPrayers";
const String taskName = "getAndSavePrayers";

void main() {
  WidgetsFlutterBinding.ensureInitialized();
  Workmanager.initialize(callbackDispatcher, isInDebugMode: true);
  Workmanager.registerPeriodicTask(uniqueName, taskName,
      initialDelay: Duration(minutes: 1),
      frequency: Duration(hours: 20),
      constraints: Constraints(
          networkType: NetworkType.not_required,
          requiresBatteryNotLow: false,
          requiresCharging: false,
          requiresDeviceIdle: false,
          requiresStorageNotLow: false));
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'GetPrayer',
      theme: ThemeData(
        brightness: Brightness.dark,
        primarySwatch: Colors.cyan,
      ),
      home: GetPrayersPage(),
    );
  }
}

class GetPrayersPage extends StatefulWidget {
  @override
  _GetPrayersPageState createState() => _GetPrayersPageState();
}

class _GetPrayersPageState extends State<GetPrayersPage> {
  tz.TZDateTime fajr;
  tz.TZDateTime dhuhr;
  tz.TZDateTime maghrib;
  tz.TZDateTime asr;
  tz.TZDateTime isha;
  @override
  void initState() {
    super.initState();

    loalData();
  }

  void loalData() async {
    fajr = await PrayerTime.instance.getFajr();
    dhuhr = await PrayerTime.instance.getdhuhr();
    maghrib = await PrayerTime.instance.getmaghrib();
    asr = await PrayerTime.instance.getasr();
    isha = await PrayerTime.instance.getisha();
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Prayer times'),
        elevation: 0.0,
      ),
      body: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          ListTile(
            leading: Icon(Icons.calendar_today),
            title: Text("Fajr"),
            trailing: Text("${fajr.toString()}"),
          ),
          ListTile(
            leading: Icon(Icons.calendar_today),
            title: Text("Dhuhr"),
            trailing: Text("${dhuhr.toString()}"),
          ),
          ListTile(
            leading: Icon(Icons.calendar_today),
            title: Text("Maghrib"),
            trailing: Text("${maghrib.toString()}"),
          ),
          ListTile(
            leading: Icon(Icons.calendar_today),
            title: Text("Asr"),
            trailing: Text("${asr.toString()}"),
          ),
          ListTile(
            leading: Icon(Icons.calendar_today),
            title: Text("Isha"),
            trailing: Text("${isha.toString()}"),
          ),
        ],
      ),
      bottomNavigationBar: Container(
        child: ElevatedButton(
          style: ButtonStyle(
              minimumSize:
                  MaterialStateProperty.all(Size(double.infinity, 60))),
          onPressed: () {
            PrayerTime.instance.getPrayers();
          },
          child: Text("UPDATE"),
        ),
      ),
    );
  }
}

void callbackDispatcher() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case taskName:
        PrayerTime.instance.getPrayers();
        await NotificationManager().initNotificationManager();
        await NotificationManager().zonedNotification();
        await NotificationManager().showNotification();
        break;
    }
    return Future.value(true);
  });
  print(taskName + "callbackDispatcher");
}

祈祷时间.dart

import 'package:adhan/adhan.dart';
import 'package:notify/local_notification/get_timezone_date.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:timezone/timezone.dart' as tz;

class PrayerTime {
  static const String fajrKey = "fajr";
  static const String sunriseKey = "sunrise";
  static const String dhuhrKey = "dhuhr";
  static const String asrKey = "asr";
  static const String maghribKey = "maghrib";
  static const String ishaKey = "maghrib";

  PrayerTime._privateConstructor();

  static final PrayerTime _instance = PrayerTime._privateConstructor();

  static PrayerTime get instance => _instance;

  List<String> prayerTimesList = [];

  void getPrayers() async {
    final myCoordinates = Coordinates(19.076090, 72.877426);
    final params = CalculationMethod.karachi.getParameters();
    params.madhab = Madhab.hanafi;
    final prayerTimes = PrayerTimes.today(myCoordinates, params);
    final datewa = DateTime.now().add(Duration(minutes: 5));
    String _formatTime(DateTime time) {
      return time.toIso8601String();
    }

    savePrayers(
      fajr: _formatTime(datewa),
      // fajr: _formatTime(prayerTimes.fajr),
      dhuhr: _formatTime(prayerTimes.dhuhr),
      asr: _formatTime(prayerTimes.asr),
      maghrib: _formatTime(prayerTimes.maghrib),
      isha: _formatTime(prayerTimes.isha),
    );
  }

  void savePrayers({
    String fajr,
    String dhuhr,
    String asr,
    String maghrib,
    String isha,
  }) async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    await prefs.setString(fajrKey, fajr);
    await prefs.setString(dhuhrKey, dhuhr);
    await prefs.setString(asrKey, asr);
    await prefs.setString(maghribKey, maghrib);
    await prefs.setString(ishaKey, isha);
  }

  Future<tz.TZDateTime> getFajr() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return convertToTZ(DateTime.parse(prefs.getString(fajrKey)));
  }

  Future<tz.TZDateTime> getdhuhr() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return convertToTZ(DateTime.parse(prefs.getString(dhuhrKey)));
  }

  Future<tz.TZDateTime> getasr() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return convertToTZ(DateTime.parse(prefs.getString(asrKey)));
  }

  Future<tz.TZDateTime> getmaghrib() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return convertToTZ(DateTime.parse(prefs.getString(maghribKey)));
  }

  Future<tz.TZDateTime> getisha() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    return convertToTZ(DateTime.parse(prefs.getString(ishaKey)));
  }
}

manage_notification.dart

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';
import 'package:notify/prayer_times.dart';
import 'package:timezone/timezone.dart' as tz;

class NotificationManager {
  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;
  AndroidInitializationSettings initializationSettingsAndroid;
  IOSInitializationSettings initializationSettingsIOS;
  InitializationSettings initializationSettings;

  /// Initializing FlutterLocalNotificationsPlugin.
  Future initNotificationManager() async {
    flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    initializationSettingsAndroid =
        AndroidInitializationSettings('ic_launcher');
    initializationSettingsIOS = IOSInitializationSettings();
    initializationSettings = InitializationSettings(
        android: initializationSettingsAndroid, iOS: initializationSettingsIOS);
    await flutterLocalNotificationsPlugin.initialize(initializationSettings);
  }

  Future<void> zonedNotification() async {
    /// List of prayer times.
    List<tz.TZDateTime> _times = [
      await PrayerTime.instance.getFajr(),
      await PrayerTime.instance.getdhuhr(),
      await PrayerTime.instance.getmaghrib(),
      await PrayerTime.instance.getasr(),
      await PrayerTime.instance.getisha(),
    ];

    /// Vibration pattern.
    var vibrationPattern = Int64List(4);
    vibrationPattern[0] = 0;
    vibrationPattern[1] = 1000;
    vibrationPattern[2] = 5000;
    vibrationPattern[3] = 2000;

    /// Android Specifics.
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        "0", "channel Name", "channel Description",
        icon: 'ic_launcher',
        sound: RawResourceAndroidNotificationSound("slow_spring_board"),
        largeIcon: DrawableResourceAndroidBitmap('ic_launcher'),
        vibrationPattern: vibrationPattern,
        autoCancel: false,
        enableLights: true,
        playSound: true,
        color: Colors.green,
        ledColor: const Color.fromARGB(255, 255, 0, 0),
        ledOnMs: 1000,
        ledOffMs: 500);

    /// iOS Specifics.
    IOSNotificationDetails iOSPlatformChannelSpecifics =
        IOSNotificationDetails(sound: 'slow_spring_board.aiff');

    /// Platform channel specifics.
    NotificationDetails platformChannelSpecifics = NotificationDetails(
        android: androidPlatformChannelSpecifics,
        iOS: iOSPlatformChannelSpecifics);

    /// ZonedSchedule
    _times.forEach((element) async {
      await flutterLocalNotificationsPlugin.zonedSchedule(
          0, "Title", "Body", element, platformChannelSpecifics,
          uiLocalNotificationDateInterpretation:
              UILocalNotificationDateInterpretation.absoluteTime,
          androidAllowWhileIdle: true);
    });
  }

  Future<void> showNotification() async {
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        "1", 'channel name', 'channel description',
        importance: Importance.high, priority: Priority.high, ticker: 'ticker');
    var iOSPlatformChannelSpecifics = IOSNotificationDetails();
    var platformChannelSpecifics = NotificationDetails(
        android: androidPlatformChannelSpecifics,
        iOS: iOSPlatformChannelSpecifics);
    await flutterLocalNotificationsPlugin.show(
        0, 'plain title', 'plain body', platformChannelSpecifics,
        payload: 'item x');
  }
}

get_timezone.dart

import 'package:timezone/data/latest.dart';
import 'package:timezone/timezone.dart' as tz;
import 'package:flutter_native_timezone/flutter_native_timezone.dart';

class TimeZone {
  factory TimeZone() => _this ?? TimeZone._();

  TimeZone._() {
    initializeTimeZones();
  }
  static TimeZone _this;

  Future<String> getTimeZoneName() async =>
      FlutterNativeTimezone.getLocalTimezone();

  Future<tz.Location> getLocation([String timeZoneName]) async {
    if (timeZoneName == null || timeZoneName.isEmpty) {
      timeZoneName = await getTimeZoneName();
    }
    return tz.getLocation(timeZoneName);
  }
}

Future<tz.TZDateTime> convertToTZ(dateTime) async {
  final timeZone = TimeZone();
  String timeZoneName = await timeZone.getTimeZoneName();
  final location = await timeZone.getLocation(timeZoneName);
  final scheduledDate = tz.TZDateTime.from(dateTime, location);
  print(scheduledDate.toString());
  return scheduledDate;
}

flutter 医生

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.0.1, on Linux, locale en_US.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
[✓] Chrome - develop for the web
[!] Android Studio (not installed)
[✓] VS Code (version 1.54.3)
[✓] Connected device (2 available)

! Doctor found issues in 1 category.

pubspec.yaml *

version: 1.0.0+1

environment:
  sdk: ">=2.7.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter
  workmanager: ^0.2.3
  shared_preferences: ^2.0.5
  adhan: ^1.1.15
  intl: ^0.17.0
  background_location: ^0.4.1
  flutter_local_notifications: 4.0.1+2
  flutter_native_timezone: ^1.0.10
  # The following adds the Cupertino Icons font to your application.
  # Use the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.2

dev_dependencies:
  flutter_test:
    sdk: flutter

Answer 1

在 try/catch 中调用您的代码并查看错误并将您的实例设置为变量:

try {
    PrayerTime.instance.getPrayers();
    NotificationManager manager = new NotificationManager();
    await manager.initNotificationManager();
    await manager.zonedNotification();
    await manager.showNotification();
} catch(e) {
      print(e);
}