Xamarin 警报管理器 Android

Posted 2023-04-13

【中文标题】Xamarin 警报管理器 Android

【英文标题】：Xamarin AlarmManager Android

【发布时间】：2016-07-27 09:55:20

【问题描述】：

我创建了一个快速的 xamarin android 项目。最终我会想把下面的学习应用到一个在 android 和 ios 之间共享的 xamarin forms 项目中。现在我只关注 Android 方面的事情。

我一直在尝试了解如何安排本地通知在未来某个时间出现。做了一个快速扔掉的应用程序，下面是我写的AlarmReceiver类，以及下面的MainActivity.cs。

class AlarmReceiver : BroadcastReceiver

    public override void OnReceive(Context context, Intent intent)
    
        var message = intent.GetStringExtra("message");
        var title = intent.GetStringExtra("title");

        var notIntent = new Intent(context, typeof(MainActivity));
        var contentIntent = PendingIntent.GetActivity(context, 0, notIntent, PendingIntentFlags.CancelCurrent);
        var manager = NotificationManager.FromContext(context);

        //Generate a notification with just short text and small icon
        var builder = new Notification.Builder(context)
                        .SetContentIntent(contentIntent)
                        .SetContentTitle(title)
                        .SetContentText(message)
                        .SetWhen(Java.Lang.JavaSystem.CurrentTimeMillis())
                        .SetAutoCancel(true);

        var notification = builder.Build();
        manager.Notify(0, notification);
    


public class MainActivity : Activity

    // Unique ID for our notification: 
    private static readonly int ButtonClickNotificationId = 1000;

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

    protected override void OnCreate(Bundle bundle)
    
        base.OnCreate(bundle);
        SetContentView(Resource.Layout.Main);

        // Display the "Hello World, Click Me!" button and register its event handler:
        Button button = FindViewById<Button>(Resource.Id.MyButton);
        button.Click += ButtonOnClick;
    

    // Handler for button click events.
    private void ButtonOnClick(object sender, EventArgs eventArgs)
    
        Intent alarmIntent = new Intent(Application.Context, typeof(AlarmReceiver));
        alarmIntent.PutExtra("message", "This is my test message!");
        alarmIntent.PutExtra("title", "This is my test title!");

        PendingIntent pendingIntent = PendingIntent.GetBroadcast(Application.Context, 0, alarmIntent, PendingIntentFlags.UpdateCurrent);
        AlarmManager alarmManager = (AlarmManager)Application.Context.GetSystemService(Context.AlarmService);            
        alarmManager.Set(AlarmType.ElapsedRealtime, SystemClock.ElapsedRealtime() + 1 * 1000, pendingIntent);           
    

当我逐步调试它时，我的 OnReceive 方法似乎没有被调用。

我一直在关注这篇文章，因为我很难通过谷歌搜索来研究如何正确地做到这一点。这里：Scheduled Notifications

如果有人能分享一些智慧，将不胜感激。

【参考方案1】：

问题是您的BroadcastReceiver 没有[BroadcastReceiver] 属性。

此代码有效：

AlarmReceiver.cs

[BroadcastReceiver]
public class AlarmReceiver : BroadcastReceiver

    public override void OnReceive(Context context, Intent intent)
    
        var message = intent.GetStringExtra("message");
        var title = intent.GetStringExtra("title");

        var resultIntent = new Intent(context, typeof(MainActivity));
        resultIntent.SetFlags(ActivityFlags.NewTask | ActivityFlags.ClearTask);

        var pending = PendingIntent.GetActivity(context, 0,
            resultIntent,
            PendingIntentFlags.CancelCurrent);

        var builder =
            new Notification.Builder(context)
                .SetContentTitle(title)
                .SetContentText(message)
                .SetSmallIcon(Resource.Drawable.Icon)
                .SetDefaults(NotificationDefaults.All);

        builder.SetContentIntent(pending);

        var notification = builder.Build();

        var manager = NotificationManager.FromContext(context);
        manager.Notify(1337, notification);
    

MainActivity.cs

[Activity(Label = "App3", MainLauncher = true, Icon = "@drawable/icon")]
public class MainActivity : Activity

    protected override void OnCreate(Bundle bundle)
    
        base.OnCreate(bundle);

        SetContentView(Resource.Layout.Main);

        var button = FindViewById<Button>(Resource.Id.MyButton);

        button.Click += delegate
        
            var alarmIntent = new Intent(this, typeof(AlarmReceiver));
            alarmIntent.PutExtra("title", "Hello");
            alarmIntent.PutExtra("message", "World!");

            var pending = PendingIntent.GetBroadcast(this, 0, alarmIntent, PendingIntentFlags.UpdateCurrent);

            var alarmManager = GetSystemService(AlarmService).JavaCast<AlarmManager>();
            alarmManager.Set(AlarmType.ElapsedRealtime, SystemClock.ElapsedRealtime() + 5*1000, pending);
        ;
    

【讨论】：

好的，我们正在取得进展。是的，在添加 [BroadcastReceiver] 之后，我看到调试器在 OnReceive 方法中达到了我的断点。但是通知本身仍未出现在我的测试中。我们现在大约完成了一半。

似乎没有为它设置任何图标时它不会显示出来。让我更新我的答案。

如何以特定分钟的时间间隔重复警报

@sudharsanchandrasekaran 创建一个新问题来描述您的问题。