为什么预定的通知没有在固定时间出现，而是应用程序返回到 Android Java 中的主 Activity？

Question

我想在特定日期前一天的固定时间在我的 Android 应用程序中推送通知。我已经在主要活动中创建了一个频道。

以下是第三个 Activity 中负责调度通知的方法的代码：

private void scheduleNotification(LocalDate date, String doctorName) {
    try {
        if (date != null) {
            LocalDate notificationDate = date.minusDays(1);
            Calendar calendar = Calendar.getInstance();
        
            calendar.set(notificationDate.getYear(), notificationDate.getMonthValue() - 1, notificationDate.getDayOfMonth(), 2, 2, 0);
            AlarmManager alarmManager = (AlarmManager) getSystemService(Context.ALARM_SERVICE);
            Intent intent = new Intent(getBaseContext(), AppointmentNotificationReceiver.class);
intent.putExtra("doctor_name", doctorName);
            PendingIntent pendingIntent = PendingIntent.getBroadcast(getBaseContext(), 0, intent, PendingIntent.FLAG_IMMUTABLE);
  
            alarmManager.setExact(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
            Toast.makeText(getBaseContext(), "Notification scheduled for " + notificationDate.format(DateTimeFormatter.ofPattern("dd.MM.yyyy")) + " at 13:00.", Toast.LENGTH_LONG).show();        
       }
    } catch (Exception e) {
            Toast.makeText(getBaseContext(), "Error scheduling notification: " + e.getMessage() + ".", Toast.LENGTH_LONG).show();
    }
}

这是通知接收器类的代码。

public class AppointmentNotificationReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String doctorName = intent.getStringExtra("doctor_name");
        NotificationCompat.Builder builder = new NotificationCompat.Builder(context, "ID12345678FFRREE")
                .setContentTitle("Remainder")
                .setContentText("Tomorrow.")
                .setPriority(NotificationCompat.PRIORITY_DEFAULT);
        NotificationManagerCompat notificationManager = NotificationManagerCompat.from(context);
        if (ActivityCompat.checkSelfPermission(context, android.Manifest.permission.POST_NOTIFICATIONS) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling            //    ActivityCompat#requestPermissions            // here to request the missing permissions, and then overriding            //   public void onRequestPermissionsResult(int requestCode, String[] permissions,            //                                          int[] grantResults)            // to handle the case where the user grants the permission. See the documentation            // for ActivityCompat#requestPermissions for more details.
           return;
        }
        notificationManager.notify(200, builder.build());    
     }
}

这是主活动中用于创建通道的代码部分：

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
    NotificationChannel channel = new NotificationChannel("ID12345678FFRREE", "Channel",  NotificationManager.IMPORTANCE_DEFAULT);
    channel.setDescription("desc");
    NotificationManager notificationManager = getSystemService(NotificationManager.class);
    notificationManager.createNotificationChannel(channel);
}

一切正常，但根本不出现通知。相反，在通知的固定时间，如果我当前处于不同的活动，应用程序将返回到第一个活动（主活动）。

Answer 1

这样做就可以了：

public class AppointmentNotificationReceiver extends BroadcastReceiver {
    @Override
    public void onReceive(Context context, Intent intent) {
        String doctorName = intent.getStringExtra("doctor_name");
        NotificationCompat.Builder builder = new NotificationCompat.Builder(context, "ID12345678FFRREE")
                .setContentTitle("Remainder")
                .setContentText("Tomorrow.")
                .setPriority(NotificationCompat.PRIORITY_DEFAULT);
        NotificationManagerCompat notificationManager = NotificationManagerCompat.from(context);
        NotificationChannel channel = new NotificationChannel("ID12345678FFRREE", "Channel",  NotificationManager.IMPORTANCE_DEFAULT);
        channel.setDescription("desc");
        NotificationManager notificationManager = context.getSystemService(NotificationManager.class);
        notificationManager.createNotificationChannel(channel);
        if (ActivityCompat.checkSelfPermission(context, android.Manifest.permission.POST_NOTIFICATIONS) != PackageManager.PERMISSION_GRANTED) {
            // TODO: Consider calling
           return;
        }
        notificationManager.notify(200, builder.build());    
     }
}