android之Android 应用程序中 startForeground 的错误通知

我正在使用 Xamarin Android 3.5 开发一项服务。我们的应用程序面向 Android 8.1 (API 27 - Oreo)。我希望该服务作为前台服务运行。但是，当我运行该服务时，出现以下错误。

Bad notification for startForeground: java.lang.RuntimeException: invalid channel for service notification: Notification(channel=null pri=1 contentView=null vibrate=null sound=null defaults=0x0 flags=0x42 color=0x00000000 vis=PRIVATE) 

这是该服务的代码。

public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId) 
{ 
  base.OnStartCommand(intent, flags, startId); 
  var context = Application.Context; 
  const int pendingIntentId = 0; 
  PendingIntent pendingIntent = PendingIntent.GetActivity(context, pendingIntentId, intent, PendingIntentFlags.OneShot); 
  var notification = new NotificationCompat.Builder(context) 
    .SetContentTitle("Testing") 
    .SetContentText("location tracking has begun.") 
    .SetSmallIcon(Resource.Drawable.icon) 
    .SetContentIntent(pendingIntent) 
    .SetOngoing(true) 
    .Build(); 
    // Enlist this instance of the service as a foreground service 
    const int Service_Running_Notification_ID = 935; 
    StartForeground(Service_Running_Notification_ID, notification); 
    return StartCommandResult.NotSticky; 
} 

我已使用以下内容更新了 AndroidManifest.xml。

<uses-permission android:name="android.permission.FOREGROUND_SERVICE" /> 

在MainActivity.c中，我有以下代码，我们用它来创建用于发送应用程序通知的通知 channel (并且正确地创建了通知 channel )。

private void CreateNotificationChannel() 
{ 
  if (Build.VERSION.SdkInt < BuildVersionCodes.O) 
  { 
    // Notification channels are new in API 26 (and not a part of the 
    // support library). There is no need to create a notification  
    // channel on older versions of Android. 
    return; 
  } 
  var channel = new NotificationChannel(ApplicationConstants.ChannelId, ApplicationConstants.ChannelName, NotificationImportance.Default) 
  { 
    Description = ApplicationConstants.ChannelDescription 
  }; 
  var notificationManager = (NotificationManager)GetSystemService(NotificationService); 
  notificationManager.CreateNotificationChannel(channel); 
} 

请您参考如下方法:

对于 Xamarin.Forms 和 Xamarin.Android

========将此代码放在公共(public)重写 StartCommandResult OnStartCommand ===========

 if (Build.VERSION.SdkInt >= Build.VERSION_CODES.O) 
      RegisterForegroundServiceO(); 
  else { RegisterForegroundService(); } 

==========================================END====== =======================

 void RegisterForegroundService() 
        { 
            var notification = new Notification.Builder(this) 
                .SetContentTitle(Resources.GetString(Resource.String.app_name)) 
                .SetContentText(Resources.GetString(Resource.String.notification_text)) 
                .SetSmallIcon(Resource.Drawable.icon_userProfile) 
                .SetContentIntent(BuildIntentToShowMainActivity()) 
                .SetOngoing(true) 
                .Build(); 
            const int Service_Running_Notification_ID = 936; 
            StartForeground(Service_Running_Notification_ID, notification); 
        } 
 
 
void RegisterForegroundServiceO() 
    { 
        String NOTIFICATION_CHANNEL_ID = "com.Your.project.id"; 
        NotificationChannel chan = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "Your Channel Name", NotificationManager.ImportanceHigh); 
 
        NotificationManager manager = (NotificationManager)GetSystemService(Context.NotificationService); 
 
        manager.CreateNotificationChannel(chan); 
 
        NotificationCompat.Builder notificationBuilder = new NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID); 
 
        Notification notification= notificationBuilder.SetOngoing(true) 
            .SetContentTitle(Resources.GetString(Resource.String.app_name)) 
            .SetContentText(Resources.GetString(Resource.String.notification_text)) 
            .SetSmallIcon(Resource.Drawable.icon_userProfile) 
            .SetContentIntent(BuildIntentToShowMainActivity()) 
            .SetOngoing(true) 
            .Build(); 
 
        const int Service_Running_Notification_ID = 936; 
        StartForeground(Service_Running_Notification_ID, notification); 
    } 

快乐编码。 :-)