Flutter 工作管理器返回“工作结果 FAILURE for Work [ id=XXXXXxXXXXxXXXX 标签={ be.tramckrijte.workmanager.BackgroundWorker } ]”

Question

我正在构建一个应用程序，通知用户祈祷时间。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 小时变化一次，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。但我面临这个问题，有没有其他或更好的方法可以实现这一目标。

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Launching lib/main.dart on ASUS X00T in debug mode...\n\xe2\x9c\x93 Built build/app/outputs/flutter-apk/app-debug.apk.\nConnecting to VM Service at ws://127.0.0.1:44753/d5gE32RyvC4=/ws\nI/.example.notif(14281): Waiting for a blocking GC ProfileSaver\nE/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: Invalid argument(s) (input): Must not be null\n[38;5;244mE/flutter (14281): #0      _RegExp.firstMatch (dart:core-patch/regexp_patch.dart:221:24)[39;49m\n[38;5;244mE/flutter (14281): #1      DateTime.parse (dart:core/date_time.dart:266:23)[39;49m\n[38;5;248mE/flutter (14281): #2      PrayerTime.getFajr[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;248mE/flutter (14281): #3      _GetPrayersPageState.loalData[39;49m\nE/flutter (14281): <asynchronous suspension>\nE/flutter (14281):\nE/cutils-trace(14281): Error opening trace file: No such file or directory (2)\nI/flutter (14281): getAndSavePrayerscallbackDispatcher\nI/flutter (14281): 2021-03-25 13:07:32.419749+0530\nI/flutter (14281): 2021-03-25 12:45:00.000+0530\nI/flutter (14281): 2021-03-25 20:04:00.000+0530\nI/flutter (14281): 2021-03-25 17:08:00.000+0530\nI/flutter (14281): 2021-03-25 20:04:00.000+0530\nE/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The method 'zonedSchedule' was called on null.\nE/flutter (14281): Receiver: null\nE/flutter (14281): Tried calling: zonedSchedule(0, "Title", "Body", Instance of 'TZDateTime', Instance of 'NotificationDetails', androidAllowWhileIdle: true, uiLocalNotificationDateInterpretation: Instance of 'UILocalNotificationDateInterpretation')\n[38;5;244mE/flutter (14281): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)[39;49m\n[38;5;248mE/flutter (14281): #1      NotificationManager.zonedNotification.<anonymous closure>[39;49m\n[38;5;248mE/flutter (14281): #2      NotificationManager.zonedNotification.<anonymous closure>[39;49m\n[38;5;244mE/flutter (14281): #3      List.forEach (dart:core-patch/growable_array.dart:403:8)[39;49m\n[38;5;248mE/flutter (14281): #4      NotificationManager.zonedNotification[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;248mE/flutter (14281): #5      callbackDispatcher.<anonymous closure>[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;244mE/flutter (14281): #6      MethodChannel._handleAsMethodCall[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;244mE/flutter (14281): #7      _DefaultBinaryMessenger.handlePlatformMessage[39;49m\nE/flutter (14281): <asynchronous suspension>\nE/flutter (14281):\nI/chatty  (14281): uid=10412(com.example.notify) 2.ui identical 3 lines\nE/flutter (14281): [ERROR:flutter/lib/ui/ui_dart_state.cc(186)] Unhandled Exception: NoSuchMethodError: The method 'zonedSchedule' was called on null.\nE/flutter (14281): Receiver: null\nE/flutter (14281): Tried calling: zonedSchedule(0, "Title", "Body", Instance of 'TZDateTime', Instance of 'NotificationDetails', androidAllowWhileIdle: true, uiLocalNotificationDateInterpretation: Instance of 'UILocalNotificationDateInterpretation')\n[38;5;244mE/flutter (14281): #0      Object.noSuchMethod (dart:core-patch/object_patch.dart:54:5)[39;49m\n[38;5;248mE/flutter (14281): #1      NotificationManager.zonedNotification.<anonymous closure>[39;49m\n[38;5;248mE/flutter (14281): #2      NotificationManager.zonedNotification.<anonymous closure>[39;49m\n[38;5;244mE/flutter (14281): #3      List.forEach (dart:core-patch/growable_array.dart:403:8)[39;49m\n[38;5;248mE/flutter (14281): #4      NotificationManager.zonedNotification[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;248mE/flutter (14281): #5      callbackDispatcher.<anonymous closure>[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;244mE/flutter (14281): #6      MethodChannel._handleAsMethodCall[39;49m\nE/flutter (14281): <asynchronous suspension>\n[38;5;244mE/flutter (14281): #7      _DefaultBinaryMessenger.handlePlatformMessage[39;49m\nE/flutter (14281): <asynchronous suspension>\nE/flutter (14281):\nI/WM-WorkerWrapper(14281): Worker result FAILURE for Work [ id=0a8091e2-1677-4fc9-9fbd-79468e004d97, tags={ be.tramckrijte.workmanager.BackgroundWorker } ]\n\n

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主程序.dart

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import 'dart:async';\nimport 'package:flutter/material.dart';\nimport 'package:notify/local_notification/manage_notification.dart';\nimport 'package:notify/prayer_times.dart';\nimport 'package:workmanager/workmanager.dart';\nimport 'package:timezone/timezone.dart' as tz;\n\nconst String uniqueName = "getPrayers";\nconst String taskName = "getAndSavePrayers";\n\nvoid main() {\n  WidgetsFlutterBinding.ensureInitialized();\n  Workmanager.initialize(callbackDispatcher, isInDebugMode: true);\n  Workmanager.registerPeriodicTask(uniqueName, taskName,\n      initialDelay: Duration(minutes: 1),\n      frequency: Duration(hours: 20),\n      constraints: Constraints(\n          networkType: NetworkType.not_required,\n          requiresBatteryNotLow: false,\n          requiresCharging: false,\n          requiresDeviceIdle: false,\n          requiresStorageNotLow: false));\n  runApp(MyApp());\n}\n\nclass MyApp extends StatelessWidget {\n  // This widget is the root of your application.\n  @override\n  Widget build(BuildContext context) {\n    return MaterialApp(\n      title: 'GetPrayer',\n      theme: ThemeData(\n        brightness: Brightness.dark,\n        primarySwatch: Colors.cyan,\n      ),\n      home: GetPrayersPage(),\n    );\n  }\n}\n\nclass GetPrayersPage extends StatefulWidget {\n  @override\n  _GetPrayersPageState createState() => _GetPrayersPageState();\n}\n\nclass _GetPrayersPageState extends State<GetPrayersPage> {\n  tz.TZDateTime fajr;\n  tz.TZDateTime dhuhr;\n  tz.TZDateTime maghrib;\n  tz.TZDateTime asr;\n  tz.TZDateTime isha;\n  @override\n  void initState() {\n    super.initState();\n\n    loalData();\n  }\n\n  void loalData() async {\n    fajr = await PrayerTime.instance.getFajr();\n    dhuhr = await PrayerTime.instance.getdhuhr();\n    maghrib = await PrayerTime.instance.getmaghrib();\n    asr = await PrayerTime.instance.getasr();\n    isha = await PrayerTime.instance.getisha();\n    setState(() {});\n  }\n\n  @override\n  Widget build(BuildContext context) {\n    return Scaffold(\n      appBar: AppBar(\n        title: Text('Prayer times'),\n        elevation: 0.0,\n      ),\n      body: Column(\n        mainAxisSize: MainAxisSize.min,\n        children: [\n          ListTile(\n            leading: Icon(Icons.calendar_today),\n            title: Text("Fajr"),\n            trailing: Text("${fajr.toString()}"),\n          ),\n          ListTile(\n            leading: Icon(Icons.calendar_today),\n            title: Text("Dhuhr"),\n            trailing: Text("${dhuhr.toString()}"),\n          ),\n          ListTile(\n            leading: Icon(Icons.calendar_today),\n            title: Text("Maghrib"),\n            trailing: Text("${maghrib.toString()}"),\n          ),\n          ListTile(\n            leading: Icon(Icons.calendar_today),\n            title: Text("Asr"),\n            trailing: Text("${asr.toString()}"),\n          ),\n          ListTile(\n            leading: Icon(Icons.calendar_today),\n            title: Text("Isha"),\n            trailing: Text("${isha.toString()}"),\n          ),\n        ],\n      ),\n      bottomNavigationBar: Container(\n        child: ElevatedButton(\n          style: ButtonStyle(\n              minimumSize:\n                  MaterialStateProperty.all(Size(double.infinity, 60))),\n          onPressed: () {\n            PrayerTime.instance.getPrayers();\n          },\n          child: Text("UPDATE"),\n        ),\n      ),\n    );\n  }\n}\n\nvoid callbackDispatcher() {\n  Workmanager.executeTask((task, inputData) async {\n    switch (task) {\n      case taskName:\n        PrayerTime.instance.getPrayers();\n        await NotificationManager().initNotificationManager();\n        await NotificationManager().zonedNotification();\n        await NotificationManager().showNotification();\n        break;\n    }\n    return Future.value(true);\n  });\n  print(taskName + "callbackDispatcher");\n}\n\n

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祈祷时间.dart

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import 'package:adhan/adhan.dart';\nimport 'package:notify/local_notification/get_timezone_date.dart';\nimport 'package:shared_preferences/shared_preferences.dart';\nimport 'package:timezone/timezone.dart' as tz;\n\nclass PrayerTime {\n  static const String fajrKey = "fajr";\n  static const String sunriseKey = "sunrise";\n  static const String dhuhrKey = "dhuhr";\n  static const String asrKey = "asr";\n  static const String maghribKey = "maghrib";\n  static const String ishaKey = "maghrib";\n\n  PrayerTime._privateConstructor();\n\n  static final PrayerTime _instance = PrayerTime._privateConstructor();\n\n  static PrayerTime get instance => _instance;\n\n  List<String> prayerTimesList = [];\n\n  void getPrayers() async {\n    final myCoordinates = Coordinates(19.076090, 72.877426);\n    final params = CalculationMethod.karachi.getParameters();\n    params.madhab = Madhab.hanafi;\n    final prayerTimes = PrayerTimes.today(myCoordinates, params);\n    final datewa = DateTime.now().add(Duration(minutes: 5));\n    String _formatTime(DateTime time) {\n      return time.toIso8601String();\n    }\n\n    savePrayers(\n      fajr: _formatTime(datewa),\n      // fajr: _formatTime(prayerTimes.fajr),\n      dhuhr: _formatTime(prayerTimes.dhuhr),\n      asr: _formatTime(prayerTimes.asr),\n      maghrib: _formatTime(prayerTimes.maghrib),\n      isha: _formatTime(prayerTimes.isha),\n    );\n  }\n\n  void savePrayers({\n    String fajr,\n    String dhuhr,\n    String asr,\n    String maghrib,\n    String isha,\n  }) async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    await prefs.setString(fajrKey, fajr);\n    await prefs.setString(dhuhrKey, dhuhr);\n    await prefs.setString(asrKey, asr);\n    await prefs.setString(maghribKey, maghrib);\n    await prefs.setString(ishaKey, isha);\n  }\n\n  Future<tz.TZDateTime> getFajr() async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    return convertToTZ(DateTime.parse(prefs.getString(fajrKey)));\n  }\n\n  Future<tz.TZDateTime> getdhuhr() async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    return convertToTZ(DateTime.parse(prefs.getString(dhuhrKey)));\n  }\n\n  Future<tz.TZDateTime> getasr() async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    return convertToTZ(DateTime.parse(prefs.getString(asrKey)));\n  }\n\n  Future<tz.TZDateTime> getmaghrib() async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    return convertToTZ(DateTime.parse(prefs.getString(maghribKey)));\n  }\n\n  Future<tz.TZDateTime> getisha() async {\n    SharedPreferences prefs = await SharedPreferences.getInstance();\n    return convertToTZ(DateTime.parse(prefs.getString(ishaKey)));\n  }\n}\n

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管理通知.dart

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import 'dart:typed_data';\nimport 'package:flutter/material.dart';\nimport 'package:flutter_local_notifications/flutter_local_notifications.dart';\nimport 'package:notify/prayer_times.dart';\nimport 'package:timezone/timezone.dart' as tz;\n\nclass NotificationManager {\n  FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;\n  AndroidInitializationSettings initializationSettingsAndroid;\n  IOSInitializationSettings initializationSettingsIOS;\n  InitializationSettings initializationSettings;\n\n  /// Initializing FlutterLocalNotificationsPlugin.\n  Future initNotificationManager() async {\n    flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();\n    initializationSettingsAndroid =\n        AndroidInitializationSettings('ic_launcher');\n    initializationSettingsIOS = IOSInitializationSettings();\n    initializationSettings = InitializationSettings(\n        android: initializationSettingsAndroid, iOS: initializationSettingsIOS);\n    await flutterLocalNotificationsPlugin.initialize(initializationSettings);\n  }\n\n  Future<void> zonedNotification() async {\n    /// List of prayer times.\n    List<tz.TZDateTime> _times = [\n      await PrayerTime.instance.getFajr(),\n      await PrayerTime.instance.getdhuhr(),\n      await PrayerTime.instance.getmaghrib(),\n      await PrayerTime.instance.getasr(),\n      await PrayerTime.instance.getisha(),\n    ];\n\n    /// Vibration pattern.\n    var vibrationPattern = Int64List(4);\n    vibrationPattern[0] = 0;\n    vibrationPattern[1] = 1000;\n    vibrationPattern[2] = 5000;\n    vibrationPattern[3] = 2000;\n\n    /// Android Specifics.\n    var androidPlatformChannelSpecifics = AndroidNotificationDetails(\n        "0", "channel Name", "channel Description",\n        icon: 'ic_launcher',\n        sound: RawResourceAndroidNotificationSound("slow_spring_board"),\n        largeIcon: DrawableResourceAndroidBitmap('ic_launcher'),\n        vibrationPattern: vibrationPattern,\n        autoCancel: false,\n        enableLights: true,\n        playSound: true,\n        color: Colors.green,\n        ledColor: const Color.fromARGB(255, 255, 0, 0),\n        ledOnMs: 1000,\n        ledOffMs: 500);\n\n    /// iOS Specifics.\n    IOSNotificationDetails iOSPlatformChannelSpecifics =\n        IOSNotificationDetails(sound: 'slow_spring_board.aiff');\n\n    /// Platform channel specifics.\n    NotificationDetails platformChannelSpecifics = NotificationDetails(\n        android: androidPlatformChannelSpecifics,\n        iOS: iOSPlatformChannelSpecifics);\n\n    /// ZonedSchedule\n    _times.forEach((element) async {\n      await flutterLocalNotificationsPlugin.zonedSchedule(\n          0, "Title", "Body", element, platformChannelSpecifics,\n          uiLocalNotificationDateInterpretation:\n              UILocalNotificationDateInterpretation.absoluteTime,\n          androidAllowWhileIdle: true);\n    });\n  }\n\n  Future<void> showNotification() async {\n    var androidPlatformChannelSpecifics = AndroidNotificationDetails(\n        "1", 'channel name', 'channel description',\n        importance: Importance.high, priority: Priority.high, ticker: 'ticker');\n    var iOSPlatformChannelSpecifics = IOSNotificationDetails();\n    var platformChannelSpecifics = NotificationDetails(\n        android: androidPlatformChannelSpecifics,\n        iOS: iOSPlatformChannelSpecifics);\n    await flutterLocalNotificationsPlugin.show(\n        0, 'plain title', 'plain body', platformChannelSpecifics,\n        payload: 'item x');\n  }\n}\n\n

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获取时区.dart

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import 'package:timezone/data/latest.dart';\nimport 'package:timezone/timezone.dart' as tz;\nimport 'package:flutter_native_timezone/flutter_native_timezone.dart';\n\nclass TimeZone {\n  factory TimeZone() => _this ?? TimeZone._();\n\n  TimeZone._() {\n    initializeTimeZones();\n  }\n  static TimeZone _this;\n\n  Future<String> getTimeZoneName() async =>\n      FlutterNativeTimezone.getLocalTimezone();\n\n  Future<tz.Location> getLocation([String timeZoneName]) async {\n    if (timeZoneName == null || timeZoneName.isEmpty) {\n      timeZoneName = await getTimeZoneName();\n    }\n    return tz.getLocation(timeZoneName);\n  }\n}\n\nFuture<tz.TZDateTime> convertToTZ(dateTime) async {\n  final timeZone = TimeZone();\n  String timeZoneName = await timeZone.getTimeZoneName();\n  final location = await timeZone.getLocation(timeZoneName);\n  final scheduledDate = tz.TZDateTime.from(dateTime, location);\n  print(scheduledDate.toString());\n  return scheduledDate;\n}\n\n

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扑医生

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Doctor summary (to see all details, run flutter doctor -v):\n[\xe2\x9c\x93] Flutter (Channel stable, 2.0.1, on Linux, locale en_US.UTF-8)\n[\xe2\x9c\x93] Android toolchain - develop for Android devices (Android SDK version 30.0.3)\n[\xe2\x9c\x93] Chrome - develop for the web\n[!] Android Studio (not installed)\n[\xe2\x9c\x93] VS Code (version 1.54.3)\n[\xe2\x9c\x93] Connected device (2 available)\n\n! Doctor found issues in 1 category.\n

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pubspec.yaml *

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version: 1.0.0+1\n\nenvironment:\n  sdk: ">=2.7.0 <3.0.0"\n\ndependencies:\n  flutter:\n    sdk: flutter\n  workmanager: ^0.2.3\n  shared_preferences: ^2.0.5\n  adhan: ^1.1.15\n  intl: ^0.17.0\n  background_location: ^0.4.1\n  flutter_local_notifications: 4.0.1+2\n  flutter_native_timezone: ^1.0.10\n  # The following adds the Cupertino Icons font to your application.\n  # Use the CupertinoIcons class for iOS style icons.\n  cupertino_icons: ^1.0.2\n\ndev_dependencies:\n  flutter_test:\n    sdk: flutter\n

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Answer 1

在 try/catch 中调用您的代码并查看错误并将实例设置为变量：

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