Flutter - FCM：如何将后台消息存储到 SQLite

Question

我正在为我的移动应用程序构建一个通知系统，其想法是将从 Firebase Cloud 消息接收到的前台消息和后台消息存储到 SQLite。我已经按照guideline 在这里设置了我的项目。

这是我的代码：

void initState() {
    super.initState();
    service = MySQLService();

    _firebaseMessaging.configure(
      onMessage: (Map<String, dynamic> message) async {
        print("onMessage: $message");
        service.insertItem(Item.fromMessage(message)); // It's working, here.
      },
      onBackgroundMessage: myBackgroundMessageHandler,
      onLaunch: (Map<String, dynamic> message) async {
        print("onLaunch: $message");
      },
      onResume: (Map<String, dynamic> message) async {
        print("onResume: $message");
      },
    );

    _firebaseMessaging.requestNotificationPermissions(
        const IosNotificationSettings(
            sound: true, badge: true, alert: true, provisional: true));
    _firebaseMessaging.onIosSettingsRegistered
        .listen((IosNotificationSettings settings) {
      print("Settings registered: $settings");
    });
    _firebaseMessaging.getToken().then((String token) {
      assert(token != null);
      print("Push Messaging token: $token");
    });
}

以及处理后台消息的代码：

Future<dynamic> myBackgroundMessageHandler(Map<String, dynamic> message) async {
  print("onBackground: $message");
  var service = MySQLService();
  await service.insertItem(Item.fromMessage(message)); // It's not working, here.
  return Future<void>.value();
}

目前，我的应用程序可以： 接收前台消息并将其存储到 SQLite 中（通过调用 service.insertItem），但由于某种原因，即使显示在 SQLite 上，后台消息也不会存储在 SQLite 中设备的通知列表。

更新：这里是插入消息的代码

  Future<void> insertItem(Item notification) async {
    final Database db = await MyDatabase.getDatabase();
    await db.insert('notification', notification.toMap(),
        conflictAlgorithm: ConflictAlgorithm.replace);
    return Future<void>.value();
  }

Answer 1

由于某种原因，onBackgroundMessage 仅在 FCM 消息不包含 notification 时调用（例如，是纯数据消息）。默认情况下，类似的消息不会在设备上触发通知。

我最终做的只是发送数据消息（以便能够在后台捕获它们）并使用flutter_local_modifications 包自己处理设备上的通知部分。

// TOP-LEVEL or STATIC function to handle background messages
static Future<dynamic> onBackgroundMessage(
    Map<String, dynamic> notification) async {

  var msg;
  if (Platform.isAndroid) {
    msg = notification['data'];
  } else {
    msg = notification;
  }

  DatabaseService _dbService = DatabaseService();
  msg = await _dbService.insertMessage(msg);
  _showNotification(msg);
  return Future<void>.value();
}

static Future _showNotification(Map<String, dynamic> msg) async {
  // TODO: Use a proper channel
  var platformChannelSpecificsAndroid = AndroidNotificationDetails(
      'your channel id', 'your channel name', 'your channel description',
      importance: Importance.Max, priority: Priority.High);
  var platformChannelSpecificsIos =
      IOSNotificationDetails(presentSound: true);
  var platformChannelSpecifics = NotificationDetails(
      platformChannelSpecificsAndroid, platformChannelSpecificsIos);

  return Future.delayed(Duration.zero, () {
    _flutterLocalNotificationsPlugin.show(
      "some id",
      msg["title"],
      msg["body"],
      platformChannelSpecifics,
      payload: "some id",
    );
  });
}

为此，所有相关插件必须提前注册，如下所述“默认情况下后台消息未启用。在后台处理消息”在firebase_messaging。

试图将那里写的内容翻译成一个 kotlin 项目，我最终创建了一个文件 /android/app/src/main/kotlin//Application.kt 来注册插件，例如：

package <your package>

import io.flutter.app.FlutterApplication
import io.flutter.plugin.common.PluginRegistry
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback
import io.flutter.plugins.firebasemessaging.FlutterFirebaseMessagingService
import com.tekartik.sqflite.SqflitePlugin
import com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin

public class Application: FlutterApplication(), PluginRegistrantCallback {
    override fun onCreate() {
        super.onCreate()
        FlutterFirebaseMessagingService.setPluginRegistrant(this)
    }

    override fun registerWith(registry: PluginRegistry) {
        io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin.registerWith(
                registry.registrarFor("io.flutter.plugins.firebasemessaging.FirebaseMessagingPlugin"))

        com.tekartik.sqflite.SqflitePlugin.registerWith(
                registry.registrarFor("com.tekartik.sqflite.SqflitePlugin"))

        com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin.registerWith(
                registry.registrarFor("com.dexterous.flutterlocalnotifications.FlutterLocalNotificationsPlugin"))
    }
}