Я работаю / пытаюсь загрузить файл с паузой и возобновить работу с помощью WorkManager с MVVM.
Здесь я ищу паузу / резюме и обновление прогресса загрузки в процентах с использованием WorkManager. Итак, я делюсь своими уроками здесь.
MainActivity.kt
class MainActivity : AppCompatActivity() {
lateinit var downloadViewModel : DownloaderViewModel
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
//setContentView(R.layout.activity_main)
val binding = DataBindingUtil.setContentView<ActivityMainBinding>(this,R.layout.activity_main)
downloadViewModel = ViewModelProviders.of(this).get(DownloaderViewModel::class.java)
binding.viewmodel = downloadViewModel
download_button.setOnClickListener({
startDownload()
})
cancel_button.setOnClickListener({
downloadViewModel.cancelDownloadWork(Constants.TAG_OUTPUT)
WorkUtils.deleteFile(WorkUtils.getIsbn(Constants.TAG_OUTPUT))
})
downloadViewModel.mSavedWorkStatus.observe(this, Observer {
it?.let {
}
if(it?.size!! > 0){
val workStatus = it.first()
val workState = workStatus?.state
downloadViewModel.updateDownloadWorkState(workState.toString())
WorkUtils.makeStatusNotification(workState.toString(),this.applicationContext)
}
})
pause_button.setOnClickListener({
downloadViewModel.cancelDownloadWork(Constants.TAG_OUTPUT)
val pausedAt = WorkUtils.getFileSize(WorkUtils.getIsbn(DOWNLOAD_URL))
Log.d("paused at","paused at $pausedAt")
})
resume_button.setOnClickListener({
val resumeFrom = WorkUtils.getFileSize(WorkUtils.getIsbn(DOWNLOAD_URL))
Log.d("paused at","resumed at ${resumeFrom+1}")
startDownload()
})
}
fun startDownload() {
downloadViewModel.downloadUrl = DOWNLOAD_URL
downloadViewModel.makeDownloadRequest()
}
fun isFileExists(url : String) : Boolean {
return File(WorkUtils.getAbsolutePath(WorkUtils.getIsbn(url))).exists()
}
}
Constants.kt
class Constants {
companion object {
val DOWNLOAD_URL = "download_url"
// Notification Channel constants
// Name of Notification Channel for verbose notifications of background work
val VERBOSE_NOTIFICATION_CHANNEL_NAME: CharSequence = "Verbose WorkManager Notifications"
var VERBOSE_NOTIFICATION_CHANNEL_DESCRIPTION = "Shows notifications whenever work starts"
val NOTIFICATION_TITLE: CharSequence = "WorkRequest Starting"
val CHANNEL_ID = "VERBOSE_NOTIFICATION"
val NOTIFICATION_ID = 1
// The name of the image manipulation work
internal val IMAGE_MANIPULATION_WORK_NAME = "image_manipulation_work"
// Other keys
val OUTPUT_PATH = "blur_filter_outputs"
val KEY_DOWNLOAD_URL = "KEY_DOWNLOAD_URL"
internal val TAG_OUTPUT = "OUTPUT"
val DELAY_TIME_MILLIS: Long = 3000
// Ensures this class is never instantiated
private fun Constants() {}
}
}
DownloaderViewModel.kt
Чтобы сделать запрос на загрузку и уведомить пользовательский интерфейс с помощью привязки. Отмена загрузки (работы) с использованием экземпляра WorkManager.
class DownloaderViewModel : ObservableViewModel() {
var mWorkManager : WorkManager = WorkManager.getInstance()
var mSavedWorkStatus: LiveData<List<WorkStatus>>
@Bindable
var currentDownloadState : MutableLiveData<String> = MutableLiveData()
init {
mSavedWorkStatus = mWorkManager.getStatusesByTagLiveData(Constants.TAG_OUTPUT)
}
lateinit var downloadUrl: String
/**
* Creates the input data bundle which includes the Uri to operate on
* @return Data which contains the Image Uri as a String
*/
private fun createInputData(): Data {
val builder = Data.Builder()
if (downloadUrl != null) {
builder.putString(KEY_DOWNLOAD_URL, downloadUrl)
}
return builder.build()
}
fun makeDownloadRequest() {
// Create charging constraint
val constraints = Constraints.Builder()
.setRequiredNetworkType(NetworkType.CONNECTED)
.setRequiresCharging(true)
.build()
// Add WorkRequest to download the epub to the filesystem
val save = OneTimeWorkRequest.Builder(DownloadWorker::class.java)
.setConstraints(constraints)
.setInputData(createInputData())
.addTag(TAG_OUTPUT)
.build()
mWorkManager.enqueue(save)
}
fun cancelDownloadWork(tag : String) {
mWorkManager.cancelAllWorkByTag(tag)
}
fun getDownloadWorkState() {
getOutputStatus()
}
fun updateDownloadWorkState(state: String){
currentDownloadState.value = state
notifyPropertyChanged(BR.currentDownloadState)
}
internal fun getOutputStatus(): LiveData<List<WorkStatus>> {
return mWorkManager.getStatusesByTagLiveData(TAG_OUTPUT)
}
}
Рабочий класс: DownloadWorker.kt
Этот класс использовался для начала загрузки. Поскольку сервер поддерживает запрос диапазона, каждый OneTimeWorkRequest запускается с этим рабочим диапазоном для загрузки файла.
class DownloadWorker(context : Context,workerParameters: WorkerParameters) : Worker(context,workerParameters) {
override fun doWork(): Result {
val applicationContext = applicationContext
// Makes a notification when the work starts and slows down the work so that it's easier to
// see each WorkRequest start, even on emulated devices
lateinit var result : Result
val inputData : String? = inputData.getString(KEY_DOWNLOAD_URL)
inputData?.let {
result = downloadFile(inputData)
}
return result
}
fun downloadFile(url : String) : Result {
var input: InputStream? = null
var output: OutputStream? = null
var connection: HttpURLConnection? = null
lateinit var result : Result
val isbnFileName = WorkUtils.getIsbn(url);
val filePathToWrite = WorkUtils.getAbsolutePath(isbnFileName)
//val path = "${Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES).path}${File.separator}${"file.zip"}"
Log.d("Download file path :","Download file path :"+filePathToWrite)
val targetFile = File(filePathToWrite)
if(!targetFile?.exists()){
targetFile.createNewFile()
}
try {
val urlConnection = URL(url)
connection = urlConnection.openConnection() as HttpURLConnection
val range = WorkUtils.getFileSize(isbnFileName)+1
connection.setRequestProperty("Range","bytes=${range}-")
Log.d("Range","Request header Range is $range")
connection.connect()
// expect HTTP 200 OK, so we don't mistakenly save error report
// instead of the file
if (connection.responseCode != HttpURLConnection.HTTP_OK) {
Log.e("","Server returned HTTP ${connection.responseCode} ${connection.responseMessage}")
result = Result.FAILURE
}
// download the file
input = connection.inputStream
input?.let {
output = FileOutputStream(targetFile, false)
val data = ByteArray(1024 * 4)
var count: Int
do {
count = input.read(data)
if (count != 1) {
output!!.write(data, 0, count)
} else {
break
}
} while (count != -1)
}
result = Result.SUCCESS
} catch (e: Exception) {
Log.e("Exception occured:",e.message)
result = Result.FAILURE
} finally {
try {
output?.close()
input?.close()
connection?.disconnect()
} catch (e: IOException) {
Log.e("Exception occured:",e.message)
}
}
return result
}
}
Утилиты, использованные в этом примере
Utils.kt
class WorkUtils {
companion object {
private val TAG = WorkUtils::class.java.getSimpleName()
fun makeStatusNotification(message: String, context: Context) {
// Make a channel if necessary
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
// Create the NotificationChannel, but only on API 26+ because
// the NotificationChannel class is new and not in the support library
val name = Constants.VERBOSE_NOTIFICATION_CHANNEL_NAME
val description = Constants.VERBOSE_NOTIFICATION_CHANNEL_DESCRIPTION
val importance = NotificationManager.IMPORTANCE_HIGH
val channel = NotificationChannel(Constants.CHANNEL_ID, name, importance)
channel.description = description
// Add the channel
val notificationManager = context.getSystemService(Context.NOTIFICATION_SERVICE) as NotificationManager
notificationManager?.createNotificationChannel(channel)
}
// Create the notification
val builder = NotificationCompat.Builder(context, Constants.CHANNEL_ID)
.setSmallIcon(R.mipmap.ic_launcher)
.setContentTitle(Constants.NOTIFICATION_TITLE)
.setContentText(message)
.setPriority(NotificationCompat.PRIORITY_HIGH)
.setVibrate(LongArray(0))
// Show the notification
NotificationManagerCompat.from(context).notify(Constants.NOTIFICATION_ID, builder.build())
}
/**
* Method for sleeping for a fixed about of time to emulate slower work
*/
fun sleep() {
try {
Thread.sleep(Constants.DELAY_TIME_MILLIS, 0)
} catch (e: InterruptedException) {
Log.d(TAG, e.message)
}
}
fun getIsbn(url: String) : String {
return url.substring(url.lastIndexOf("/")+1)
}
fun getAbsolutePath(isbnFileName: String): String {
return Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS).toString()+"/"+isbnFileName+".zip";
}
fun getFileSize(isbn:String) : Long {
val file: File = File(getAbsolutePath(isbn))
if(!file?.exists())
{
return 0
}else{
return file?.length()
}
}
fun deleteFile(isbn: String) {
val file = File(getAbsolutePath(isbn))
if(file.exists() && file.isFile) {
file.delete()
}
}
}
}
Для части пользовательского интерфейса с привязкой данных
<?xml version="1.0" encoding="utf-8"?>
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
>
<data>
<import type="com.pkonf.downloadebook.viewmodels.DownloaderViewModel" />
<variable
name="viewmodel"
type="com.pkonf.downloadebook.viewmodels.DownloaderViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<TextView
android:id="@+id/download_status"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:text="@{viewmodel.currentDownloadState}"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<LinearLayout
android:id="@+id/linearLayout"
android:layout_width="368dp"
android:layout_height="50dp"
android:layout_marginStart="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:orientation="horizontal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent">
<Button
android:id="@+id/pause_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="pause_button"
tools:text="Pause" />
<Button
android:id="@+id/resume_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="resume_button"
tools:text="Resume" />
</LinearLayout>
<LinearLayout
android:id="@+id/linearLayout2"
android:layout_width="377dp"
android:layout_height="157dp"
android:layout_marginStart="8dp"
android:layout_marginTop="28dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:gravity="center_horizontal|center_vertical"
android:orientation="vertical"
app:layout_constraintBottom_toTopOf="@+id/linearLayout"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="1.0"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/download_status"
app:layout_constraintVertical_bias="0.95">
<Button
android:id="@+id/download_button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="-1dp"
android:text="Download"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="@id/linearLayout2"
app:layout_constraintTop_toTopOf="@+id/linearLayout2" />
<Button
android:id="@+id/cancel_button"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginBottom="8dp"
android:text="Cancel"
app:layout_constraintBottom_toBottomOf="@+id/linearLayout2"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/download_button" />
</LinearLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
Я попытался - начать загрузку - приостановить загрузку (здесь приостановка означает отмену текущего OneTimeWorkRequest) и возобновить, создав новый OneTimeWorkRequest и запустить / возобновить с длиной загруженного файла + 1, как диапазон байтов в заголовке запроса.
Но отмена не работает в моем случае. Не знаю, что я делаю не так.
И мои вопросы
1. Можем ли мы сделать паузу и возобновить загрузку с помощью WorkManager?
2. Можем ли мы обновить индикатор выполнения с помощью WorkManager?
3. Ссылка: ссылка это единственный способ обновить индикатор выполнения?