flutter 应用关闭时是否可以发送通知？

Question

我正在使用 Flutter 开发 Android 应用程序，目前正在致力于实现通知。我已经成功设置了每周通知，但我想添加一个条件：仅当应用程序一周未打开时才触发通知。即使应用程序关闭，这也应该有效。

如何在 Flutter 中实现这个逻辑？

我已经探索了

flutter_local_notifications

和后台执行的选项，但我不确定跟踪应用程序上次打开时间并相应触发通知的最佳方法。

这是我的代码：

import 'package:flutter_local_notifications/flutter_local_notifications.dart';

class NotificationService {
  final FlutterLocalNotificationsPlugin notificationsPlugin = FlutterLocalNotificationsPlugin();

  Future<void> initNotification() async {
    notificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()?.requestNotificationsPermission();
    notificationsPlugin.resolvePlatformSpecificImplementation<AndroidFlutterLocalNotificationsPlugin>()?.requestExactAlarmsPermission();
  }

  Future<void> scheduleNotification() async {
    const AndroidNotificationDetails androidNotificationDetails =
    AndroidNotificationDetails(
        'repeating channel id', 'repeating channel name',
        channelDescription: 'repeating description',
        icon: '@drawable/sn_invent');
    const NotificationDetails notificationDetails =
    NotificationDetails(android: androidNotificationDetails);
    await notificationsPlugin.periodicallyShow(0, 'Ziele in Angriff genommen?',
        'Schau doch gerne mal wieder deinen Zielplan an', RepeatInterval.weekly, notificationDetails,
        androidAllowWhileIdle: true);
  }
}

Answer 1

您需要跟踪应用程序何时打开以及应用程序何时关闭。您可以通过

shared_preferences

来做到这一点

具体方法如下：

Future<void> scheduleNotification() async {
    if (await shouldTriggerNotification()) {
      const AndroidNotificationDetails androidNotificationDetails =
          AndroidNotificationDetails(
        'repeating channel id',
        'repeating channel name',
        channelDescription: 'repeating description',
        icon: '@drawable/sn_invent',
      );
      const NotificationDetails notificationDetails =
          NotificationDetails(android: androidNotificationDetails);
      await notificationsPlugin.periodicallyShow(
        0,
        'Ziele in Angriff genommen?',
        'Schau doch gerne mal wieder deinen Zielplan an',
        RepeatInterval.weekly,
        notificationDetails,
        androidAllowWhileIdle: true,
      );

      await updateLastOpenedTime();
    }
  }

  Future<bool> shouldTriggerNotification() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    DateTime lastOpenedTime =
        DateTime.parse(prefs.getString('lastOpenedTime') ?? '');

    int daysDifference = DateTime.now().difference(lastOpenedTime).inDays;

    return daysDifference >= 7;
  }

  Future<void> updateLastOpenedTime() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    prefs.setString('lastOpenedTime', DateTime.now().toIso8601String());
  }
}

Answer 2

在如何发送通知的逻辑中 在主类中创建计划通知，将此通知设置为静态ID，例如用户ID，然后当用户打开应用程序时，该函数将运行来自 DateTime.now().add(Duration(days:7)) 的计划通知 每次用户打开应用程序时，通知日期都会更改为该天后 7 天，但请确保通知 ID 是静态的