我的 Flutter 本地通知有一些错误

Question

我需要帮助，调用本地通知时出错。

对于 initState ：

initState() {
    super.initState();
    flutterLocalNotificationsPlugin = new FlutterLocalNotificationsPlugin();
    // initialise the plugin. app_icon needs to be a added as a drawable resource to the Android head project
    var initializationSettingsAndroid =
        new AndroidInitializationSettings('app_icon');
    var initializationSettingsIOS = new IOSInitializationSettings();
    var initializationSettings = new InitializationSettings(
        initializationSettingsAndroid, initializationSettingsIOS);
    FlutterLocalNotificationsPlugin().initialize(initializationSettings, onSelectNotification: onSelectNotification);
  }

对于功能：

showNotification() async {
    var android = new AndroidNotificationDetails('Channel ID', 'Channel Name', 'channelDescription');
    var iOS = new IOSNotificationDetails();
    var platform = new NotificationDetails(android, iOS);
    await flutterLocalNotificationsPlugin.show(
      0, 'New Notification', 'Flutter Local Notif', platform,payload: 'test notification');
  }

错误是“PlatformException (PlatformException(error, Attempt to invoke virtual method 'int java.lang.Integer.intValue()' on an null object reference, null))”

我已经尝试过文档和 youtube，但我总是收到此错误消息

Answer 1

我遇到过这个问题，就我而言，这是一个图标问题app_icon
在你的 initState 函数中替换这个

 var initializationSettingsAndroid = new AndroidInitializationSettings('app_icon');

有了这个

 var initializationSettingsAndroid = new AndroidInitializationSettings('@mipmap/ic_launcher');

希望对你有所帮助。

Answer 2

这个对我有用，你可以给个机会

  @override
  initState() {
    super.initState();
to the Android head project
    var initializationSettingsAndroid =
    AndroidInitializationSettings('app_icon');
    var initializationSettingsIOS = IOSInitializationSettings(
        onDidReceiveLocalNotification: onDidReceiveLocalNotification);
    var initializationSettings = InitializationSettings(
        initializationSettingsAndroid, initializationSettingsIOS);
    flutterLocalNotificationsPlugin.initialize(initializationSettings,
        onSelectNotification: onSelectNotification);
  }



  Future<void> _showNotification() async {
    var androidPlatformChannelSpecifics = AndroidNotificationDetails(
        'your channel id', 'your channel name', 'your channel description',
        importance: Importance.Max, priority: Priority.High, ticker: 'ticker');
    var iOSPlatformChannelSpecifics = IOSNotificationDetails();
    var platformChannelSpecifics = NotificationDetails(
        androidPlatformChannelSpecifics, iOSPlatformChannelSpecifics);
    await flutterLocalNotificationsPlugin.show(
        0, 'plain title', 'plain body', platformChannelSpecifics,
        payload: 'item x');
  }



 Future<void> onSelectNotification(String payload) async {
    if (payload != null) {
      debugPrint('notification payload: ' + payload);
    }
}

Answer 3

您的插件初始化有问题。我在您的代码中看到，您创建了实例 flutterLocalNotificationsPlugin 但使用 FlutterLocalNotificationsPlugin().initialize() 代替。然后您尝试使用尚未初始化的已创建实例显示通知。

出于同样的原因，我收到此错误 - 我的 FlutterLocalNotificationsPlugin 未正确初始化。为了检查它是否是，我尝试了以下代码：

void main() {
  runApp(MyApp());
  initializeNotification(); //Its Important to place this line after runApp() otherwise FlutterLocalNotificationsPlugin will not be initialize and you will get the error as mentioned in the question.
}


void initializeNotification() async {
  try {
    flutterLocalNotificationsPlugin = FlutterLocalNotificationsPlugin();
    var initializationSettingsAndroid = AndroidInitializationSettings('app_icon');
    var initializationSettingsIOS = IOSInitializationSettings();
    var initializationSettings = InitializationSettings(initializationSettingsAndroid, initializationSettingsIOS);
    await flutterLocalNotificationsPlugin.initialize(initializationSettings, onSelectNotification: didSelectNotification);
  } catch(e) {
   print(e.toString());
  }
}

如果它捕捉到任何异常，说明你的flutterLocalNotificationsPlugin还没有初始化，你会得到一个错误。

还尝试将初始化代码包装在单独的 async-await 函数中。

Answer 4

在我的例子中，我将app_icon.png 添加到 android drawables 中，在这个路径中：MY_PROJECT\android\app\src\main\res\drawable

在此处查看源代码 https://github.com/MaikuB/flutter_local_notifications/tree/master/flutter_local_notifications/example/android/app/src/main/res/drawable

将所有可绘制对象复制粘贴到您的项目中，它会起作用。

并且不要忘记将这些接收者添加到清单中

<receiver android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationReceiver" />
    <receiver android:name="com.dexterous.flutterlocalnotifications.ScheduledNotificationBootReceiver">
        <intent-filter>
            <action android:name="android.intent.action.BOOT_COMPLETED"/>
            <action android:name="android.intent.action.MY_PACKAGE_REPLACED"/>
        </intent-filter>
    </receiver> 

Answer 5

将您的app_icon.png 添加到MY_PROJECT\android\app\src\main\res\drawable\app_icon.png

但是，对我来说，错误在于 androidInitialization。我是这样初始化的：

var androidInit = AndroidInitializationSettings('app_icon.png');

此处不应添加.png。我知道这可能很愚蠢，但如果它可以帮助任何面临同样问题的人，那么你就去吧！这是正确的方法：

var androidInit = AndroidInitializationSettings('app_icon');

Answer 6

要在android平台初始化本地通知设置，您必须指定通知图标名称，否则通知将不会在android平台中显示。如果您只是在 AndroidInitializationSettings 类中给出图像名称，则通知图标必须放在 android res/drawable 文件夹下。您也可以查看flutter local notifications example 以获取更多参考。

var androidSettings = AndroidInitializationSettings('app_icon');

Answer 7

对我来说，在创建 AndroidInitializationSettings 之前将 WidgetsFlutterBinding.ensureInitialized(); 添加到 main.dart 会有帮助。