Android WorkManager PeriodicWorkRequest不'；应用程序关闭时无法工作

我需要在应用程序关闭时创建通知，我尝试执行以下方法：

通知员：

class NotificationWorker(context: Context, params: WorkerParameters) :
    CoroutineWorker(context, params) {

    private lateinit var notificationManager: NotificationManager


    override suspend fun doWork(): Result {
        initNotifications()
        notificationManager.notify(0, createNotification())
        return Result.success()
    }

    private fun initNotifications() {
        notificationManager = getSystemService(
            applicationContext,
            NotificationManager::class.java
        ) as NotificationManager

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            val importance = NotificationManager.IMPORTANCE_LOW
            val channel =
                NotificationChannel(NOTIFICATION_CHANNEL, NOTIFICATION_CHANNEL, importance)
            notificationManager.createNotificationChannel(channel)
        }
    }

    private fun createNotification(): Notification {
        val builder = if (Build.VERSION.SDK_INT < Build.VERSION_CODES.O)
            Notification.Builder(applicationContext) else
            Notification.Builder(applicationContext, NOTIFICATION_CHANNEL)

        builder.apply {
            setContentTitle("Current time")
            setContentText("${Calendar.getInstance()}")
            setSmallIcon(R.drawable.ic_launcher_foreground)
        }
        return builder.build()
    }

    companion object {
        private const val NOTIFICATION_CHANNEL = "syncended.news"

        private fun getWorkerRequest(): PeriodicWorkRequest =
            PeriodicWorkRequestBuilder<NotificationWorker>(15, TimeUnit.MINUTES).build()


        fun enqueueSelf(context: Context) {
            WorkManager.getInstance(context).enqueueUniquePeriodicWork(
                NotificationWorker::class.java.name,
                ExistingPeriodicWorkPolicy.KEEP,
                getWorkerRequest()
            )
        }
    }
}

我在清单中创建了接收者和提供者：

<provider
    android:name="androidx.work.impl.WorkManagerInitializer"
    android:authorities="${applicationId}.workmanager-init"
    android:exported="false"
    tools:node="remove" />
<receiver
    android:name=".notifications.NotificationsStartReceiver"
    android:process=":newsBgNotify" />

---

一些中国OEM手机（如Oppo）在用户从“最近使用的应用”选项卡中刷下应用后，会关闭应用（停止后台服务）。这是主要原因。要防止这些设备这样做，请转到设置->应用程序设置->“YourApp”和“启用后台服务”

一些中国OEM手机（如Oppo）在用户从“最近使用的应用程序”选项卡中刷下应用程序后关闭应用程序（停止后台服务）。这是主要原因。要阻止这些设备这样做，请转到设置->应用程序设置->“YourApp”和“启用后台服务”

<provider
    android:name="androidx.work.impl.WorkManagerInitializer"
    android:authorities="${applicationId}.workmanager-init"
    android:exported="false"
    tools:node="remove" />
<receiver
    android:name=".notifications.NotificationsStartReceiver"
    android:process=":newsBgNotify" />

2020-05-04 15:06:26.678 2046-2159/system_process W/InputDispatcher: channel '68c8279 ru.syncended.news/ru.syncended.news.main.MainActivity (server)' ~ Consumer closed input channel or an error occurred.  events=0x9
2020-05-04 15:06:26.679 2046-2159/system_process E/InputDispatcher: channel '68c8279 ru.syncended.news/ru.syncended.news.main.MainActivity (server)' ~ Channel is unrecoverably broken and will be disposed!