Android Background Processing

Sep 23 2022 · Kotlin 1.6, Android 12, Android Studio Chipmunk 2021.2.1

Part 2: Use WorkManager in Complex Apps

11. Challenge - WorkManager

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Previous episode: 10. Chain Work Next episode: 12. Use DownloadManager

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Notes: 11. Challenge - WorkManager

The student materials have been reviewed and are updated as of SEPTEMBER 2022.

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Nice job repeating the concepts from the first part of the course, and reaching your first challenge in this part! :] In this challenge, you have to implement a few things! You need to create not one, but two new workers!

class ClearLocalStorageWorker(context: Context, workerParameters: WorkerParameters) :
    Worker(context, workerParameters) {

  override fun doWork(): Result {
    val rootFolder = applicationContext.externalMediaDirs.first()

    rootFolder?.listFiles()?.forEach {
      if (it.isDirectory) {
        it.deleteRecursively()
      } else {
        it.delete()
      }
    }

    return Result.success()
  }
}
class SynchronizeImagesWorker(context: Context, workerParameters: WorkerParameters) :
    Worker(context, workerParameters) {

  override fun doWork(): Result {
    val images = inputData.getStringArray("images") ?: return Result.failure()

    images.forEach { imagePath ->
      val file = File(applicationContext.externalMediaDirs.first(), imagePath)
      FileUtils.downloadImage(file, imagePath)
    }

    return Result.success()
  }
}
  fun downloadImage(file: File, imageDownloadPath: String) {
    val imageUrl = URL("$BASE_URL/files/$imageDownloadPath")

    val connection = imageUrl.openConnection() as HttpURLConnection
    connection.doInput = true
    connection.connect()

    val inputStream = connection.inputStream

    val outputStream = FileOutputStream(file)
    outputStream.use { output ->
      val buffer = ByteArray(4 * 1024)

      var byteCount = inputStream.read(buffer)
      while (byteCount > 0) {
        output.write(buffer, 0, byteCount)

        byteCount = inputStream.read(buffer)
      }

      output.flush()
    }
  }
val imagePath = parts.last()
val file = File(applicationContext.externalMediaDirs.first(), imagePath)

FileUtils.downloadImage(file, imagePath)
  private val remoteApi = App.remoteApi
  private val networkStatusChecker by lazy {
    NetworkStatusChecker(activity?.getSystemService(ConnectivityManager::class.java))
  }
    syncImages.setOnClickListener {
      networkStatusChecker.performIfConnectedToInternet {
        GlobalScope.launch(Dispatchers.Main) {
          val result = remoteApi.getImages()

          if (result is Success) {
            val images = result.data.map { it.imagePath }
            synchronizeImages(images)
          }
        }
      }
    }
  }
  private fun synchronizeImages(images: List<String>) {
    val clearStorageWorker = OneTimeWorkRequestBuilder<ClearLocalStorageWorker>()
        .build()

    val synchronizeImagesWorker = OneTimeWorkRequestBuilder<SynchronizeImagesWorker>()
        .setInputData(workDataOf("images" to images.toTypedArray()))
        .build()

    val workManager = WorkManager.getInstance(requireActivity())

    workManager.beginWith(clearStorageWorker)
        .then(synchronizeImagesWorker)
        .enqueue()

    workManager.getWorkInfoByIdLiveData(synchronizeImagesWorker.id).observe(this, Observer {
      if (it.state.isFinished) {
        activity?.toast("Synchronized images!")
      }
    })
  }