虽然之前在 Stack Overflow 上可能有人问过这个问题，但我仍然没有找到明确的答案。

例如，我想在每天中午 12 点显示通知，即使应用已关闭。我从这些链接中引用了:Notifications in specific time every day android , Android daily repeating notification at specific time of a day using AlarmManager , Android BroadcastReceiver on startup - keep running when Activity is in Background还有更多……我对 Service 和 BroadcastReceiver 之间的区别感到困惑。我应该使用哪一个？还是我应该同时使用它们？

到目前为止，我知道如何显示通知，但我不知道如何每天自动显示一次，即使应用已关闭也是如此。

我的代码:

public class NotifyService extends Service {

    @Override
    public IBinder onBind(Intent intent) {
        return null;
    }

    @Override
    public void onCreate() {
        super.onCreate();
        Toast.makeText(this, "Service created", Toast.LENGTH_LONG).show();

        Intent resultIntent = new Intent(this, HomeScreen.class).setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        PendingIntent resultPendingIntent = PendingIntent.getActivity(this, 0, resultIntent, 0);

        Notification.Builder notification = new Notification.Builder(this)
                .setSmallIcon(R.mipmap.ic_launcher)
                .setContentTitle("App Title")
                .setContentText("Some Text...")
                .setContentIntent(resultPendingIntent);

        NotificationManager notificationManager = (NotificationManager) getSystemService(Context.NOTIFICATION_SERVICE);
        if (Build.VERSION.SDK_INT < 16) {
            notificationManager.notify(1, notification.getNotification());
        } else {
            notificationManager.notify(1, notification.build());
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        Toast.makeText(this, "Service destroyed", Toast.LENGTH_LONG).show();
    }
}

AppManifest.xml:

<service android:name=".NotifyService" />

我应该如何编写代码来完成我想要的？我可以从中理解的任何建议或任何好的链接？

最佳答案

这是更新的解决方案，适用于 Android Oreo

第 1 步:在您的 MainActivity 中创建一个方法，并使用 AlarmManager 在指定时间设置闹钟。

public void myAlarm() {
  
    Calendar calendar = Calendar.getInstance();
    calendar.set(Calendar.HOUR_OF_DAY, 21);
    calendar.set(Calendar.MINUTE, 47);
    calendar.set(Calendar.SECOND, 0);
    
    if (calendar.getTime().compareTo(new Date()) < 0) 
        calendar.add(Calendar.DAY_OF_MONTH, 1);

    Intent intent = new Intent(getApplicationContext(), NotificationReceiver.class);
    PendingIntent pendingIntent = PendingIntent.getBroadcast(getApplicationContext(), 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
    AlarmManager alarmManager = (AlarmManager) getSystemService(ALARM_SERVICE);
    
    if (alarmManager != null) {
        alarmManager.setRepeating(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), AlarmManager.INTERVAL_DAY, pendingIntent);

  }
  
}

我将闹钟设置在 09:47 PM

第 2 步: 创建 BroadcastReceiver 以在警报发生时监听

public class NotificationReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {

    NotificationHelper notificationHelper = new NotificationHelper(context);
    notificationHelper.createNotification();

   }
}

我正在创建名为 NotificationReceiver 的类并扩展 BroadcastReceiver，在 onReceive 中有一个名为 NotificationHelper 的类，不要混淆我会在接下来的步骤中解释这个类。

第 3 步:创建通知类

class NotificationHelper {

private Context mContext;
private static final String NOTIFICATION_CHANNEL_ID = "10001";

NotificationHelper(Context context) {
    mContext = context;
}

void createNotification()
{
   
    Intent intent = new Intent(mContext , NotificationActivity.class);
   
    intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);

    PendingIntent resultPendingIntent = PendingIntent.getActivity(mContext,
            0 /* Request code */, intent,
            PendingIntent.FLAG_UPDATE_CURRENT);


    NotificationCompat.Builder mBuilder = new NotificationCompat.Builder(mContext, NOTIFICATION_CHANNEL_ID);
    mBuilder.setSmallIcon(R.mipmap.ic_launcher);
    mBuilder.setContentTitle("Title")
            .setContentText("Content")
            .setAutoCancel(false)
            .setSound(Settings.System.DEFAULT_NOTIFICATION_URI)
            .setContentIntent(resultPendingIntent);

    NotificationManager mNotificationManager = (NotificationManager) mContext.getSystemService(Context.NOTIFICATION_SERVICE);

    if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O)
    {
        int importance = NotificationManager.IMPORTANCE_HIGH;
        NotificationChannel notificationChannel = new NotificationChannel(NOTIFICATION_CHANNEL_ID, "NOTIFICATION_CHANNEL_NAME", importance);
        notificationChannel.enableLights(true);
        notificationChannel.setLightColor(Color.RED);
        notificationChannel.enableVibration(true);
        notificationChannel.setVibrationPattern(new long[]{100, 200, 300, 400, 500, 400, 300, 200, 400});
        assert mNotificationManager != null;
        mBuilder.setChannelId(NOTIFICATION_CHANNEL_ID);
        mNotificationManager.createNotificationChannel(notificationChannel);
    }
    assert mNotificationManager != null;
    mNotificationManager.notify(0 /* Request Code */, mBuilder.build());
       }
     }

这个类处理通知

第 4 步:回到第 2 步:并调用通知类

 NotificationHelper notificationHelper = new NotificationHelper(context);
 notificationHelper.createNotification();

注册广播接收器 转到您的 Androidmanifest 文件并注册您的广播接收器

<receiver
    android:name=".NotificationReceiver"></receiver>

有关更多信息，请参阅 this来自谷歌的指南

希望对你有帮助。

关于android - 即使应用程序已关闭，如何每天在特定时间显示通知？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/33055129/