Android Background Processing
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Next episode: 20. Communicate Using BroadcastReceivers
Notes: 19. Create Foreground Services
The student materials have been reviewed and are updated as of SEPTEMBER 2022.
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As you’ve learned so far, services in Android Oreo and higher are restricted.
const val NOTIFICATION_CHANNEL_NAME = "Synchronize service channel"
const val NOTIFICATION_CHANNEL_ID = "Synchronize ID"
class SynchronizeImagesService : Service() {
private val remoteApi by lazy { App.remoteApi }
override fun onBind(intent: Intent?): IBinder? = null
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
showNotification()
clearStorage()
fetchImages()
return START_NOT_STICKY
}
}
const val NOTIFICATION_CHANNEL_NAME = "Synchronize service channel"
const val NOTIFICATION_CHANNEL_ID = "Synchronize ID"
class SynchronizeImagesService : Service() {
...
private fun showNotification() {
createNotificationChannel()
val notificationIntent = Intent(this, MainActivity::class.java).apply {
flags = Intent.FLAG_ACTIVITY_SINGLE_TOP
}
val pendingIntent = PendingIntent.getActivity(this,
0, notificationIntent, 0)
val notification = NotificationCompat.Builder(this, NOTIFICATION_CHANNEL_ID)
.setContentTitle("Synchronization service")
.setContentText("Downloading images")
.setContentIntent(pendingIntent)
.build()
startForeground(1, notification)
}
...
}
const val NOTIFICATION_CHANNEL_NAME = "Synchronize service channel"
const val NOTIFICATION_CHANNEL_ID = "Synchronize ID"
class SynchronizeImagesService : Service() {
...
private fun createNotificationChannel() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
val serviceChannel = NotificationChannel(
NOTIFICATION_CHANNEL_ID,
NOTIFICATION_CHANNEL_NAME,
NotificationManager.IMPORTANCE_DEFAULT
)
val manager = getSystemService(NotificationManager::class.java)
manager?.createNotificationChannel(serviceChannel)
}
}
...
}
fun queueImagesForDownload(context: Context, images: Array<String>) {
if (images.isNotEmpty()) {
images.forEach { imageUrl ->
val file = File(context.externalMediaDirs.first(), imageUrl)
downloadImage(file, imageUrl)
}
}
}
private fun synchronizeImages() {
val intent = Intent(requireContext(), SynchronizeImagesService::class.java)
activity?.startService(intent)
}