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Esegui la migrazione dei servizi in primo piano a job di trasferimento di dati avviati dall'utente

Android 14 applies strict rules on when apps are allowed to use foreground services.

Also in Android 14 we are introducing a new API to specify that a job must be a user-initiated data transfer job. This API is helpful for use cases that require longer-duration, user-initiated transferring of data, such as downloading a file from a remote server. These types of tasks should use a user-initiated data transfer job.

User-initiated data transfer jobs are started by the user. These jobs require a notification, start immediately, and may be able to run for an extended period of time as system conditions allow. You can run several user-initiated data transfer jobs concurrently.

User initiated jobs must be scheduled while the application is visible to the user (or in one of the allowed conditions). After all constraints are met, user initiated jobs can be executed by the OS, subject to system health restrictions. The system may also use the provided estimated payload size to determine how long the job executes.

Autorizzazione per job di trasferimento di dati avviati dall'utente

I job di trasferimento di dati avviati dall'utente richiedono una nuova autorizzazione per essere eseguiti: RUN_USER_INITIATED_JOBS. Il sistema concede automaticamente questa autorizzazione. Il sistema genera un SecurityException se non dichiari l'autorizzazione nel file manifest dell'app.

Processo per la pianificazione di job di trasferimento di dati avviati dall'utente

Per eseguire un job avviato dall'utente:

Se è la prima volta che dichiari un'API con JobScheduler, dichiara JobService e le autorizzazioni associate nel manifest. Inoltre, definisci una sottoclasse concreta di JobService per il trasferimento di dati:

<service android:name="com.example.app.CustomTransferService"
        android:permission="android.permission.BIND_JOB_SERVICE"
        android:exported="false">
        ...
</service>

class CustomTransferService : JobService() {
  ...
}

Dichiara l'autorizzazione RUN_USER_INITIATED_JOBS nel file manifest:

<manifest ...>
    <uses-permission android:name="android.permission.RUN_USER_INITIATED_JOBS" />
    <application ...>
        ...
    </application>
</manifest>

Chiama il nuovo metodo setUserInitiated() durante la creazione di un oggetto JobInfo. Ti consigliamo inoltre di offrire una stima delle dimensioni del payload chiamando setEstimatedNetworkBytes() durante la creazione del job:

val networkRequestBuilder = NetworkRequest.Builder()
        .addCapability(NET_CAPABILITY_INTERNET)
        .addCapability(NET_CAPABILITY_NOT_METERED)
        // Add or remove capabilities based on your requirements
        .build()

val jobInfo = JobInfo.Builder()
        // ...
        .setUserInitiated(true)
        .setRequiredNetwork(networkRequestBuilder.build())
        .setEstimatedNetworkBytes(1024 * 1024 * 1024)
        // ...
        .build()

Pianifica il job prima che inizi il trasferimento, quando l'applicazione è visibile o nell'elenco delle condizioni consentite:

val jobScheduler: JobScheduler =
    context.getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobScheduler
jobScheduler.schedule(jobInfo)

Durante l'esecuzione del job, assicurati di chiamare setNotification() sull'oggetto JobService. Questo valore viene utilizzato per comunicare all'utente che il job è in esecuzione, sia in Task Manager sia nell'area di notifica della barra di stato:

class CustomTransferService : JobService() {
  override fun onStartJob(params: JobParameters?): Boolean {
      val notification = Notification.Builder(applicationContext, NOTIFICATION_CHANNEL_ID)
              .setContentTitle("My user-initiated data transfer job")
              .setSmallIcon(android.R.mipmap.myicon)
              .setContentText("Job is running")
              .build()

      setNotification(params, notification.id, notification,
              JobService.JOB_END_NOTIFICATION_POLICY_DETACH)
      // Do the job execution.
  }
}

Aggiorna periodicamente la notifica per tenere l'utente informato sullo stato e sull'avanzamento del job. Se non riesci a determinare le dimensioni di trasferimento prima di pianificare il job o devi aggiornare la dimensione di trasferimento stimata, utilizza la nuova API updateEstimatedNetworkBytes() per aggiornare le dimensioni di trasferimento quando diventano note.
Al termine dell'esecuzione, chiama jobFinished() per segnalare al sistema che il job è stato completato o che deve essere ripianificato.

I processi di trasferimento di dati avviati dall'utente possono essere interrotti

Sia l'utente che il sistema possono interrompere i job di trasferimento avviati dall'utente.

Dall'utente, da Task Manager

The user can stop a user-initiated data transfer job that appears in the Task Manager.

At the moment that the user presses Stop, the system does the following:

Terminates your app's process immediately, including all other jobs or foreground services running.
Doesn't call onStopJob() for any running jobs.
Prevets user-visible jobs from being rescheduled.

For these reasons, it's recommended to provide controls in the notification posted for the job to allow gracefully stopping and rescheduling the job.

Note that, under special circumstances, the Stop button doesn't appear next to the job in the Task Manager, or the job isn't shown in the Task Manager at all.

Dal sistema

Unlike regular jobs, user-initiated data transfer jobs are unaffected by App Standby Buckets quotas. However, the system still stops the job if any of the following conditions occur:

A developer-defined constraint is no longer met.
The system determines that the job has run for longer than necessary to complete the data transfer task.
The system needs to prioritize system health and stop jobs due to increased thermal state.
The app process is killed due to low device memory.

When the job is stopped by the system (not by the low-memory case), the system calls onStopJob(), and the system retries the job at a time that the system deems to be optimal. Check that your app can persist data transfer state, even if onStopJob() isn't called, and that your app can restore this state when onStartJob() is called again.

Condizioni consentite per la pianificazione di job di trasferimento di dati avviati dall'utente

Apps can only start a user-initiated data transfer job if the app is in the visible window, or if the certain conditions are met. To determine when a user-initiated data transfer job can be scheduled, the system applies the same list of conditions that allow apps to start an activity from the background in special cases. Notably, this list of conditions are not the same as the set of exemptions for background-started foreground service restrictions.

The exceptions to the previous statement are the following:

If an app can launch activities from the background, they can also launch user-initiated data transfer jobs from the background.
If an app has an activity in the back stack of an existing task on the Recents screen, that alone doesn't allow a user-initiated data transfer job to run.

If the job is scheduled at some other time not listed in the allowed conditions list, the job fails and returns a RESULT_FAILURE error code.

Vincoli consentiti per i job di trasferimento di dati avviati dall'utente

To support jobs running at optimal points, Android offers the ability to assign constraints to each job type. These constraints are already available as of Android 13.

Note: The following table only compares the constraints that vary between each job type. See JobScheduler developer page or work constraints for all constraints.

The following table shows the different job types that support a given job constraint, as well as the set of job constraints that WorkManager supports. Use the search bar before the table to filter the table by the name of a job constraint method.

These are the constraints allowed with user-initiated data transfer jobs:

setBackoffCriteria(JobInfo.BACKOFF_POLICY_EXPONENTIAL)
setClipData()
setEstimatedNetworkBytes()
setMinimumNetworkChunkBytes()
setPersisted()
setNamespace()
setRequiredNetwork()
setRequiredNetworkType()
setRequiresBatteryNotLow()
setRequiresCharging()
setRequiresStorageNotLow()

Test

The following list shows some steps on how to test your app's jobs manually:

To get the job ID, get the value that is defined upon the job being built.
To run a job immediately, or to retry a stopped job, run the following command in a terminal window:
```
adb shell cmd jobscheduler run -f APP_PACKAGE_NAME JOB_ID
```
To simulate the system force-stopping a job (due to system health or out-of-quota conditions), run the following command in a terminal window:
```
adb shell cmd jobscheduler timeout TEST_APP_PACKAGE TEST_JOB_ID
```