Xamarin Android 从通知中取消任务

Question

我有一个方法，可以在每个 TimeSpan 间隔向用户发送一次本地通知：public async void GetVehiclePositionRepeatAsync(TimeSpan interval, CancellationToken cancellationToken)    {        while (true)        {            var task = new Task(() =>             {                cancellationToken.ThrowIfCancellationRequested();                var not = new PushNotificationGenerator(this, "Hooray!", "yay", "STOP_NOTIFICATIONS");                        not.Push();            });            task.Start();            await Task.Delay(interval, cancellationToken);        }    }我的目标是在通知上有两个选项；将消除当前通知，但允许此任务继续运行。对方会取消这个任务。这是 PushNotificationGenerator 类：public class PushNotificationGenerator{    public MapActivity Activity { get; set; }    public string Title { get; set; }    public string Text { get; set; }    public string ChannelId { get; set; }    public PushNotificationGenerator(MapActivity act, string title, string txt, string channelId)    {        Activity = act;        Title = title;        Text = txt;        ChannelId = channelId;    }    public void Push()    {        var resultIntent = new Intent();        resultIntent.SetAction("Dismiss");        var stackBuilder = TaskStackBuilder.Create(Activity);        stackBuilder.AddParentStack(Class.FromType(typeof(MapActivity)));        stackBuilder.AddNextIntent(resultIntent);        var resultPendingIntent = stackBuilder.GetPendingIntent(0, (int)PendingIntentFlags.UpdateCurrent);        var builder = new NotificationCompat.Builder(Activity, ChannelId)                      .SetAutoCancel(true)                      .SetContentTitle(Title)                      .SetSmallIcon(Resource.Drawable.stop_bus)                      .SetContentText(Text)                      .AddAction(0, "Dont Dismiss", resultPendingIntent)                      .AddAction(0, "Dismiss", resultPendingIntent);        var notificationManager = NotificationManagerCompat.From(Activity);        notificationManager.Notify(41144, builder.Build());    }}我不知道如何使用通知中的 CancellationToken 。

Answer 1

首先在你的Push方法中：

public void Push()

{

    ...

    Intent intentDismiss = new Intent(this, typeof(NotivicationBroadCast));

    intentDismiss.SetAction("notification_dismiss");

    PendingIntent pendingIntentDismiss = PendingIntent.GetBroadcast(this, 0,

    intentDismiss, PendingIntentFlags.UpdateCurrent);

    Intent intentCancel = new Intent(this, typeof(NotivicationBroadCast));

    intentCancel.SetAction("notification_cancel");

    PendingIntent pendingIntentCancel = PendingIntent.GetBroadcast(this, 0,

    intentCancel, PendingIntentFlags.UpdateCurrent);

    var builder = new NotificationCompat.Builder(Activity, ChannelId)

                  .SetAutoCancel(true)

                  .SetContentTitle(Title)

                  .SetSmallIcon(Resource.Drawable.stop_bus)

                  .SetContentText(Text)

                  .AddAction(0, "Dont Dismiss", pendingIntentDismiss)

                  .AddAction(0, "Dismiss", pendingIntentCancel );

    var notificationManager = NotificationManagerCompat.From(Activity);

    notificationManager.Notify(41144, builder.Build());

}

在GetVehiclePositionRepeatAsync方法中：

public async void GetVehiclePositionRepeatAsync(TimeSpan interval, CancellationToken cancellationToken)

{

        while (!cancellationToken.IsCancellationRequested) { 

            var task = new Task(() =>

            {

                cancellationToken.Token.ThrowIfCancellationRequested();

                var not = new PushNotificationGenerator(this, "Hooray!", "yay", "STOP_NOTIFICATIONS");

                not.Push();

            },cancellationToken.Token);

            task.Start();

            await Task.Delay(interval);

        }

    }

}

然后自定义NotivicationBroadCast：

[BroadcastReceiver]

class NotivicationBroadCast : BroadcastReceiver

{

    public override void OnReceive(Context context, Intent intent)

    {

        string action = intent.Action;

        if (action.Equals("notification_dismiss"))

        {

             NotificationManager notificationManager = (NotificationManager)context.GetSystemService(Context.NotificationService);            

             notificationManager.Cancel(notificationId);

        }

        if (action.Equals("notification_cancel"))

        {              

            cancellationToken.Cancel();

        }

    }

}

不要忘记在活动中注册接收器：

protected override void OnResume()

    {

        base.OnResume();

        NotivicationBroadCast recieve = new NotivicationBroadCast();

        IntentFilter intentFilter = new IntentFilter();

        intentFilter.AddAction("notification_dismiss");

        intentFilter.AddAction("notification_cancel");

        RegisterReceiver(recieve, intentFilter);

        begin();

    }