我正在开发一个Flutter应用程序，希望在其中使用flutter_local_notifications和Firebase云消息传递。当我将以下代码添加到我的main.dart时-

@pragma('vm:entry-point')
Future<void> _firebaseMessagingBackgroundHandler(RemoteMessage message) async {
  // await Firebase.initializeApp(options: DefaultFirebaseOptions.currentPlatform);
  await setupFlutterNotifications();
  showFlutterNotification(message);
  // If you're going to use other Firebase services in the background, such as Firestore,
  // make sure you call `initializeApp` before using other Firebase services.
  print('Handling a background message ${message.messageId}');
}

/// Create a [AndroidNotificationChannel] for heads up notifications
late AndroidNotificationChannel channel;

bool isFlutterLocalNotificationsInitialized = false;

Future<void> setupFlutterNotifications() async {
  if (isFlutterLocalNotificationsInitialized) {
    return;
  }
  channel = const AndroidNotificationChannel(
    'high_importance_channel', // id
    'High Importance Notifications', // title

    'This channel is used for important notifications.', // description
    importance: Importance.high,
  );

  flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();

  /// Create an Android Notification Channel.
  ///
  /// We use this channel in the `AndroidManifest.xml` file to override the
  /// default FCM channel to enable heads up notifications.
  await flutterLocalNotificationsPlugin
      .resolvePlatformSpecificImplementation<
          AndroidFlutterLocalNotificationsPlugin>()
      ?.createNotificationChannel(channel);

  /// Update the iOS foreground notification presentation options to allow
  /// heads up notifications.
  await FirebaseMessaging.instance.setForegroundNotificationPresentationOptions(
    alert: true,
    badge: true,
    sound: true,
  );
  isFlutterLocalNotificationsInitialized = true;
}

void showFlutterNotification(RemoteMessage message) {
  RemoteNotification? notification = message.notification;
  AndroidNotification? android = message.notification?.android;
  if (notification != null && android != null && !kIsWeb) {
    flutterLocalNotificationsPlugin.show(
      notification.hashCode,
      notification.title,
      notification.body,
      NotificationDetails(
        android: AndroidNotificationDetails(
          channel.id,
          channel.name,
          channel.description,
          icon: 'launch_background',
        ),
      ),
    );
  }
}

/// Initialize the [FlutterLocalNotificationsPlugin] package.
late FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin;
void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  await Firebase.initializeApp();
  // Set the background messaging handler early on, as a named top-level function
  FirebaseMessaging.onBackgroundMessage(_firebaseMessagingBackgroundHandler);

  if (!kIsWeb) {
    await setupFlutterNotifications();
  }

我发现一个错误-

android:exported needs to be explicitly specified for element <receiver#com.dexterous.flutterlocalnotifications.ScheduledNotificationBootReceiver>.  Apps targeting Android 12 and higher are required to specify an explicit value for `android:exported` when the corresponding component has an intent filter defined.

我看了几个帖子，发现我必须在AndroidManifest.xml中添加android：exported=“true”，添加后-

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.blog_app">
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.VIBRATE" />
    <uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>
   <application
        android:label="blog_app"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">
        <activity
            android:name=".MainActivity"
            android:exported="true"
            android:launchMode="singleTop"
            android:theme="@style/LaunchTheme"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:hardwareAccelerated="true"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
              android:name="io.flutter.embedding.android.NormalTheme"
              android:resource="@style/NormalTheme"
              />
            <intent-filter>
                <action android:name="android.intent.action.MAIN"/>
                <category android:name="android.intent.category.LAUNCHER"/>
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>
</manifest>

但是，在将导出的属性添加到清单文件后，我仍然收到相同的错误。只有主活动，没有其他组件。请帮助！