更新 Xamarin.Android 上的通知文本

Question

目前我有一个注册通知的应用程序：

        public void StartAppService()
        {
            ...

            using (var intent = new Intent(Application.Context, typeof(RunningAppService)))
            {
                Application.Context.StartForegroundService(intent);
            }
        }

        private const int ServiceRunningNotificationId = 10000;

        public override StartCommandResult OnStartCommand(Intent intent, StartCommandFlags flags, int startId)
        {
            CreateNotificationChannel();

            using (var notification = new Notification.Builder(this, "10111")
                .SetContentTitle("Artemis HZ")
                .SetContentText("90 HZ")
                .SetSmallIcon(Resource.Drawable.icon)
                .SetOngoing(true)
                .Build())
            {
                StartForeground(ServiceRunningNotificationId, notification);
            }

            ...

            return StartCommandResult.Sticky;
        }

        private void CreateNotificationChannel()
        {
            const string channelName = "TopAppServiceChannel";
            const string channelDescription = "TopAppServiceChannel";
            using (var channel = new NotificationChannel("10111", channelName, NotificationImportance.Default)
            {
                Description = channelDescription
            })
            {
                using (var notificationManager = (NotificationManager)GetSystemService(NotificationService))
                {
                    notificationManager?.CreateNotificationChannel(channel);
                }
            }
        }

我想以编程方式更改它的 SetContentText。 我试过这样做：

                using (var notificationBuilder = new Notification.Builder(this, "10111")
                    .SetContentText($"{(int)hz} HZ"))
                {
                    using (var notificationManager = (NotificationManager)GetSystemService(NotificationService))
                    {
                        notificationManager?.Notify(10111, notificationBuilder.Build());
                    }
                }

然后什么也没有发生。它仅在应用程序启动的最初几秒钟内有效，但之后它会保持原样，不会再次更改。

Answer 1

您提供的代码似乎没问题。当您再次发送通知时，您使用相同的通知 ID“10111”，旧通知将被覆盖。

您可以查看下面的代码，了解如何使用不同的渠道发送通知。如果您想显示更多通知，可以更改通知 ID。

[Activity(Label = "@string/app_name", Theme = "@style/AppTheme", MainLauncher = true)]
public class MainActivity : AppCompatActivity
{
    // Unique ID for our notification: 
    internal static readonly int NOTIFICATION_ID_1 = 1001;
    static readonly int NOTIFICATION_ID_2 = 1002;
    static readonly int NOTIFICATION_ID_3 = 1003;
    static readonly int NOTIFICATION_ID_4 = 1004;

    static readonly string CHANNEL_ID1 = "channel_1";
    static readonly string CHANNEL_ID2 = "channel_2";
    static readonly string PRIMARY_CHANNEL_ID = "channel_3";
    internal static readonly string COUNT_KEY = "count";

    // Number of times the button is tapped (starts with first tap):
    int count = 1;

    protected override void OnCreate(Bundle savedInstanceState)
    {
        base.OnCreate(savedInstanceState);
        Xamarin.Essentials.Platform.Init(this, savedInstanceState);
        // Set our view from the "main" layout resource
        SetContentView(Resource.Layout.Main_layout);

        CreateNotificationChannel1();
        

        // Normall CHANNEL Ntification channel
        var btnChannel = FindViewById<Button>(Resource.Id.btnChannel);
        btnChannel.Click += delegate
        {
            // Pass the current button press count value to the next activity:
            var valuesForActivity = new Bundle();
            valuesForActivity.PutInt(COUNT_KEY, count);

            // When the user clicks the notification, SecondActivity will start up. Set up an intent so that tapping the notifications returns to this app:
            var resultIntent = new Intent(this, typeof(SecondActivity));

            // Pass some values to SecondActivity:
            resultIntent.PutExtras(valuesForActivity);

            // Construct a back stack for cross-task navigation:
            var stackBuilder = Android.Support.V4.App.TaskStackBuilder.Create(this);
            stackBuilder.AddParentStack(Class.FromType(typeof(SecondActivity)));
            stackBuilder.AddNextIntent(resultIntent);

            // Create the PendingIntent with the back stack:            
            var resultPendingIntent = stackBuilder.GetPendingIntent(0, (int)PendingIntentFlags.UpdateCurrent);//FLAG

            // Build the notification:
            var builder = new NotificationCompat.Builder(this, CHANNEL_ID1)
                          .SetAutoCancel(true) // Dismiss the notification from the notification area when the user clicks on it
                          .SetContentIntent(resultPendingIntent) // Start up this activity when the user clicks the intent.
                          .SetContentTitle("Button Notification Channel_1") // Set the title
                          .SetNumber(count) // Display the count in the Content Info
                          .SetSmallIcon(Resource.Drawable.z) // This is the icon to display
                          .SetLargeIcon(BitmapFactory.DecodeResource(Resources, Resource.Drawable.Icon))
                          .SetContentText($"The button has been clicked {count} times."); // the message to display.
            builder.SetVisibility(NotificationCompat.VisibilityPublic);


            // Finally, publish the notification:
            var notificationManager = NotificationManagerCompat.From(this);
            notificationManager.Notify(NOTIFICATION_ID_1, builder.Build());

            // Increment the button press count:
            count++;
        };

        
      

      
    }

    void CreateNotificationChannel1()
    {
        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 alarmAttributes = new AudioAttributes.Builder()
               .SetContentType(AudioContentType.Sonification)
               .SetUsage(AudioUsageKind.Notification).Build();

        var path = Android.Net.Uri.Parse("android.resource://com.companyname.NotificationChannelsDemo/" + Resource.Raw.Hello);//Android.Net.Uri.Parse("ContentResolver.SchemeAndroidResource:" + "//com.companyname.NotificationChannelsDemo/" + Resource.Raw.Hello)
        var name = Resources.GetString(Resource.String.channel_name);
        var description = GetString(Resource.String.channel_description);
        var channel = new NotificationChannel(CHANNEL_ID1, name, NotificationImportance.Max)
        {
            Description = description
        };
        //channel.SetSound(path, alarmAttributes);
        var notificationManager = (NotificationManager)GetSystemService(NotificationService);
        notificationManager.CreateNotificationChannel(channel);
    }
 

    public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
    {
        Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions, grantResults);

        base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
    }
}