How to schedule notifications using WorkManager?

问题

I want to schedule a notification everytime the user add a note in the database for a specific time. While there are multiple ways to do it using AlarmManager, BroadcastReceiver etc. How can it be done using WorkManager?

回答1:

WorkManager isn't appropriate for work that needs to happen at a particular time.

You should use AlarmManager, and specifically AlarmManagerCompat.setExactAndAllowWhileIdle(), to get a callback at a specific time.

回答2:

You can show notification with the help of workmanager. Workmanger can be used for scheduling single occurrence task or periodic occurrence task as well as we can schedule task at a particular time.

OneTimeWorkRequest request= new OneTimeWorkRequest.Builder(CustomWorkerClass.class)
.setInitialDelay(delayedTime, TimeUnit.MILLISECONDS)
.addTag("TAG")
.build();

'delayedTime' -> calculate time when to trigger notification

for more implementation details click here. To read more regarding workmanager click here

回答3:

According to the Android official documentation about worker manager: "These APIs let you create a task and hand it off to WorkManager to run immediately or at an appropriate time". In my app, I set a work to be activated 20 seconds after:

 // Schedule the time
 val request= OneTimeWorkRequestBuilder<YourWork>().setInitialDelay(20, TimeUnit.SECONDS).build()
    WorkManager.getInstance().enqueue(request)

回答4:

As ianhanniballake stated

WorkManager isn't appropriate for work that needs to happen at a particular time.

But this can be set in near future of the exact time, depending on the state of the battery optimization.

An workaround will be like:

// Time to show notification at
LocalDateTime timeAt = LocalDate.now().atTime(20, 0);
LocalDateTime timeNow = LocalDateTime.now();

OneTimeWorkRequest.Builder workBuilder = new OneTimeWorkRequest.Builder(NotificationWorker.class);
// I just need to set an delay here
workBuilder.setInitialDelay(Duration.between(timeNow, timeAt));

// This is just to complete the example
WorkManager.getInstance().enqueueUniqueWork(UNIQUE_WORK_SHOW_NOTIFICATION,
                                    ExistingWorkPolicy.REPLACE,
                                    workBuilder.build());

来源：https://stackoverflow.com/questions/50299814/how-to-schedule-notifications-using-workmanager