Cómo migrar servicios en primer plano a tareas de transferencia de datos iniciados por el usuario

对于应用何时可以使用前台服务,Android 14 制定了严格的规则

此外,在 Android 14 中,我们还引入了一个新 API,用于指定作业必须是用户发起的数据传输作业。此 API 适用于需要由用户发起的持续时间较长的数据传输,例如从远程服务器下载文件。这些类型的任务应使用由用户发起的数据传输作业。

由用户发起的数据传输作业由用户启动。这些作业需要一个通知,会立即启动,并且可能在系统条件允许的情况下长时间运行。您可以同时运行多个由用户发起的数据传输作业。

必须在应用对用户可见的情况下(或在某个允许的条件下)安排由用户发起的作业。满足所有限制条件后,操作系统可以执行由用户发起的作业,具体取决于系统运行状况限制。系统还可以根据提供的估算载荷大小来确定作业的执行时长。

Permiso para tareas de transferencia de datos que inicia el usuario

Las tareas de transferencia de datos que inicia el usuario requieren un permiso nuevo para ejecutarse: RUN_USER_INITIATED_JOBS. El sistema otorga este permiso automáticamente. El sistema arroja una SecurityException si no declaras el permiso en el manifiesto de la app.

Proceso para programar tareas de transferencia de datos que inicia el usuario

To run a user initiated job, do the following:

  1. If this is your first time declaring an API with JobScheduler, declare the JobService and associated permissions in your manifest. Also, define a concrete subclass of JobService for your data transfer:

    <service android:name="com.example.app.CustomTransferService"
            android:permission="android.permission.BIND_JOB_SERVICE"
            android:exported="false">
            ...
    </service>
    
    class CustomTransferService : JobService() {
      ...
    }
    
  2. Declare the RUN_USER_INITIATED_JOBS permission in your manifest:

    <manifest ...>
        <uses-permission android:name="android.permission.RUN_USER_INITIATED_JOBS" />
        <application ...>
            ...
        </application>
    </manifest>
    
  3. Call the new setUserInitiated() method when building a JobInfo object. It is also recommended that you offer a payload size estimate by calling setEstimatedNetworkBytes() while creating your 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()
    
  4. Schedule the job before the transfer starts, while the application is visible or in the allowed conditions list:

    val jobScheduler: JobScheduler =
        context.getSystemService(Context.JOB_SCHEDULER_SERVICE) as JobScheduler
    jobScheduler.schedule(jobInfo)
    
  5. When the job is being executed, ensure you call setNotification() on the JobService object. This value is used to make the user aware that the job is running, both in the Task Manager and in the status bar notification area:

    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.
      }
    }
    
  6. Periodically update the notification to keep the user informed of the job's status and progress. If you cannot determine the transfer size ahead of scheduling the job, or need to update the estimated transfer size, use the new API, updateEstimatedNetworkBytes() to update the transfer size after it becomes known.

  7. When execution is complete, call jobFinished() to signal to the system that the job is complete, or that the job should be rescheduled.

Cómo detener las tareas de transferencia de datos que inicia el usuario

El usuario y el sistema pueden detener tareas de transferencia que inicia el usuario.

Por el usuario, desde el Administrador de tareas

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.

Por el 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.

Condiciones permitidas para programar tareas de transferencia de datos que inicia el usuario

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.

Restricciones permitidas para las tareas de transferencia de datos que inicia el usuario

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()

Pruebas

En la siguiente lista, se muestran algunos pasos para probar las tareas de tu app de forma manual:

  • Para obtener el ID de tarea, consigue el valor que se define en la tarea que se está compilando.
  • Para ejecutar una tarea de inmediato o volver a intentar una tarea detenida, ejecuta el siguiente comando en una ventana de terminal:

    adb shell cmd jobscheduler run -f APP_PACKAGE_NAME JOB_ID
    
  • Para simular que el sistema detiene, de manera forzosa, una tarea (debido al estado de este o a las condiciones de falta de cuota), ejecuta el siguiente comando en una ventana de terminal:

    adb shell cmd jobscheduler timeout TEST_APP_PACKAGE TEST_JOB_ID