Firebase 推送通知未显示

Question

我正在尝试使用 firebase 消息传递和 flutter 本地通知从 firebase 推送通知，我已将我的项目与 firebase 连接并添加了所需的插件。我可以在我的 firebase 中发布通知，但它们无法出现在应用程序中。 请问如何解决这个问题。

我的代码

main.dart

import 'package:firebase_messaging/firebase_messaging.dart';
import 'package:flutter/material.dart';
import 'package:flutter_local_notifications/flutter_local_notifications.dart';

const AndroidNotificationChannel channel = AndroidNotificationChannel(
    'high_important_channel',
    'High Important Notification',
    'This Channel is used for important notifications',
    importance: Importance.high,
    playSound: true);

final FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
    FlutterLocalNotificationsPlugin();

Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  await Firebase.initializeApp();
  print('A bg message just showed up : ${message.messageId}');
}

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

  await flutterLocalNotificationsPlugin
      .resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin>()
      ?.createNotificationChannel(channel);

  await FirebaseMessaging.instance.setForegroundNotificationPresentationOptions(
      alert: true, badge: true, sound: true);
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  @override
  void initState() {
    super.initState();
    FirebaseMessaging.onMessage.listen((RemoteMessage message) {
      RemoteNotification notification = message.notification;
      AndroidNotification android = message.notification?.android;

      if (notification != null && android != null) {
        flutterLocalNotificationsPlugin.show(
            notification.hashCode,
            notification.title,
            notification.body,
            NotificationDetails(
                android: AndroidNotificationDetails(
                    channel.id, channel.name, channel.description,
                    color: Colors.blue,
                    playSound: true,
                    icon: '@mipmap/ic_launcher')));
      }
    });

    FirebaseMessaging.onMessageOpenedApp.listen((RemoteMessage message) {
      print('A new onMessageOpenedApp was published!');
      RemoteNotification notification = message.notification;
      AndroidNotification android = message.notification?.android;

      if (notification != null && android != null) {
        showDialog(
            context: context,
            builder: (_) {
              return AlertDialog(
                title: Text(notification.title),
                content: SingleChildScrollView(
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.start,
                    children: [Text(notification.body)],
                  ),
                ),
              );
            });
      }
    });
  }

  void showNotification() {
    setState(() {
      _counter++;
    });
    flutterLocalNotificationsPlugin.show(
        0,
        'Testing $_counter',
        'Meeting tomorrow 8:30',
        NotificationDetails(
          android: AndroidNotificationDetails(
              channel.id, channel.name, channel.description,
              color: Colors.blue, playSound: true, icon: '@mipmap/ic_launcher'),
        ));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: showNotification,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

build.gradle

def localPropertiesFile = rootProject.file('local.properties')
if (localPropertiesFile.exists()) {
    localPropertiesFile.withReader('UTF-8') { reader ->
        localProperties.load(reader)
    }
}

def flutterRoot = localProperties.getProperty('flutter.sdk')
if (flutterRoot == null) {
    throw new GradleException("Flutter SDK not found. Define location with flutter.sdk in the local.properties file.")
}

def flutterVersionCode = localProperties.getProperty('flutter.versionCode')
if (flutterVersionCode == null) {
    flutterVersionCode = '1'
}

def flutterVersionName = localProperties.getProperty('flutter.versionName')
if (flutterVersionName == null) {
    flutterVersionName = '1.0'
}

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'com.google.gms.google-services'
apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

android {
    compileSdkVersion 30

    sourceSets {
        main.java.srcDirs += 'src/main/kotlin'
    }

    defaultConfig {
        // TODO: Specify your own unique Application ID (https://developer.android.com/studio/build/application-id.html).
        applicationId "com.example.notification"
        minSdkVersion 16
        targetSdkVersion 30
        versionCode flutterVersionCode.toInteger()
        versionName flutterVersionName
    }

    buildTypes {
        release {
            // TODO: Add your own signing config for the release build.
            // Signing with the debug keys for now, so `flutter run --release` works.
            signingConfig signingConfigs.debug
        }
    }
}

flutter {
    source '../..'
}

dependencies {
    implementation 'com.google.firebase:firebase-analytics'
    implementation platform('com.google.firebase:firebase-bom:28.2.0')
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}