未使用ExistingPeriodicWorkPolicy.REPLACE替换WorkManager

Question

调用ExistingPeriodicWorkPolicy.REPLACE只是启动另一个workManager，它不会替换另一个，触发时多个workManagers正在运行，而不是替换

val constraints = Constraints.Builder()
        .setRequiredNetworkType(NetworkType.CONNECTED)
        .build()

    val workRequest = PeriodicWorkRequestBuilder<SongsWorker>(1, TimeUnit.DAYS)
            .addTag(TAG)
            .setConstraints(constraints)
            .build()

    WorkManager.getInstance(mContext).enqueueUniquePeriodicWork(
        TAG, ExistingPeriodicWorkPolicy.REPLACE, workRequest)

日志显示，作业管理器至少要求取消，但执行仍在继续

I/WM-WorkerWrapper: Work [ id=6ed5487e-5d7b-4db5-a4c5-c22c562567e5, tags={ 
workerManagers.songs.SongsWorkerManager$SongsWorker } ] was cancelled
java.util.concurrent.CancellationException: Task was cancelled.
    at androidx.work.impl.utils.futures.AbstractFuture.cancellationExceptionWithCause(AbstractFuture.java:1184)
    at androidx.work.impl.utils.futures.AbstractFuture.getDoneValue(AbstractFuture.java:514)
    at androidx.work.impl.utils.futures.AbstractFuture.get(AbstractFuture.java:475)
    at androidx.work.impl.WorkerWrapper$2.run(WorkerWrapper.java:300)
    at androidx.work.impl.utils.SerialExecutor$Task.run(SerialExecutor.java:91)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
    at java.lang.Thread.run(Thread.java:923)

我已经将一个监听器附加到工作管理器，日志是

2021-04-30 20:40:54.318 17868-17868 Fragment: ID = 9f8b3165-fc75-4f9a-ba39-41c2dc6a17b3
2021-04-30 20:40:54.408 17868-17868 Fragment: ID = 9f8b3165-fc75-4f9a-ba39-41c2dc6a17b3
2021-04-30 20:40:54.427 17868-17868 Fragment: ID = 9f8b3165-fc75-4f9a-ba39-41c2dc6a17b3

监听程序是：

val instance = WorkManager.getInstance(requireContext())
  instance.getWorkInfosForUniqueWorkLiveData(SongsWorkerManager.TAG)
        .observe(viewLifecycleOwner) { workInfo ->
            workInfo.forEach {
                Log.d(TAG, "ID = ${it.id}")
            }
        }

触发工作管理器3次后，3个相同的工作管理器正在运行，而不是被替换。

Answer 1

如果其他任何人在使用ExistingPeriodicWorkPolicy.REPLACE阻止工作管理器时遇到问题，请调用

if (isStopped) return Result.success()

在doWork()中，你会得到你所期望的行为。

感谢

WorkManager.getInstance().cancelAllWorkByTag() not stopping the periodic job

“”要做到这一点，一种方法是通过调用isStopped()在doWork方法中添加一些检查，以检查工作进程是否已被取消。如果isStopped为true，则从该方法返回一个结果，而不是继续其余的工作。“”

和

How to make sure that WorkManager cancels my Worker?

Answer 2

上面的日志并不能证明老工人没有被取消。您可以添加以下观察者，通过WorkInfo查看所有工作进程的当前状态

WorkManager.getInstance(context).getWorkInfosByTagLiveData(TAG)
            .observe(lifecycleOwner, { workInfo ->
                workInfo.forEach { 
                    println("Worker Info -> $it")
                }
            })