Android Oreo - BroadcastReceiver JobIntentService无法正常工作（GCM通知）

我有一个带有GCM推送通知的应用程序 . 通知从CMS发送 .
我的appTargetSdkVersion = 27 .
一切正常，除了两个事实：

• app在Android ver低于Oreo的设备上被杀死时不会收到通知 .

• 在奥利奥上我必须打开设备屏幕才能接收通知 .

我不知道为什么它会像那样 .
*在BroadcastReceiver的onReceive方法中，我将enqueueWork和启动JobIntentService onHandleWork方法发布通知 .
*在我使用WakefulBroadcastReceiver startWakefulService IntentService之前它运行良好 . 但是我改变了这个实现，因为在将targetSdk升级到27个通知后停止在Oreo上工作（我知道它是由后台服务限制引起的） .

EDIT:
I fixed this issue by changing notification channel parameter IMPORTANCE from IMPORTANCE_DEFAULT to IMPORTANCE_HIGH!

我的GcmReceiver类：

public class GcmReceiver extends BroadcastReceiver {

@Override
public void onReceive(Context context, Intent intent) {
    ComponentName comp = new ComponentName(context.getPackageName(),
            GcmNotificationService.class.getName());
    GcmNotificationService.enqueueWork(context, (intent.setComponent(comp)));
    setResultCode(Activity.RESULT_OK);
}

}

我的JobIntentService类：

public class GcmNotificationService extends JobIntentService {

private static final String TAG = "GcmNotificationService";
private Random random = new Random();

static final int JOB_ID = 1000;

static void enqueueWork(Context context, Intent work) {
    enqueueWork(context, GcmNotificationService.class, JOB_ID, work);
}
@Override
protected void onHandleWork(Intent intent) {
    Bundle extras = intent.getExtras();
    GoogleCloudMessaging gcm = GoogleCloudMessaging.getInstance(this);

    String messageType = gcm.getMessageType(intent);

    if (!extras.isEmpty()) {
        if (GoogleCloudMessaging.MESSAGE_TYPE_SEND_ERROR.equals(messageType)) {
            Log.e(TAG, "Send error: " + extras.toString());
        } else if (GoogleCloudMessaging.MESSAGE_TYPE_DELETED.equals(messageType)) {
            Log.e(TAG, "Deleted messages on server: " + extras.toString());
        } else if (GoogleCloudMessaging.MESSAGE_TYPE_MESSAGE.equals(messageType)) {
            String title = (String) extras.get(Config.MESSAGE_TITLE);
            String description = (String) extras.get(Config.MESSAGE_TEXT);
            boolean isUpdate = false;
            try {
                isUpdate = 1 == Integer.parseInt((String) extras.get(Config.MESSAGE_UPDATE));
            } catch (NullPointerException | NumberFormatException e) {
                e.printStackTrace();
            }

            if (new Preferences(this).getBool(Constant.PREFS_NOTIFICATIONS_ENABLED, true)) {
                sendNotification(title, description, isUpdate);
            }
        }
    }
}