用户关闭应用程序时如何保持AsyncTask

Question

This is in my main activity:

   @Override
public void onBackPressed() {

    super.onBackPressed();
    finish();
    moveTaskToBack(true);
    System.exit(0);
}

I want the AsyncTask to continue put data in my server in the background after the user closes the app.

Answer 1

I want the AsyncTask to continue put data in my server in the background after the user closes the app.

The purpose of AsyncTask is NOT to perform background tasks that's beyond the scope of an Activity 's lifecycle. When a background thread is assigned from a thread pool, it expects to return it once the task is over. ie you cannot use an AsyncTask for which the required time is indefinite.

What you are looking for is Services in Android .

Why even use AsyncTask if we have services?

Well, say for instance you require to download an image/song from an Activity on click of a Button or you need to perform a task that would take some time to finish its execution. Performing these tasks from the Main thread(aka UI thread) is a bad approach and would make your app sluggish and eventually can lead to an ANR . So these tasks are to be processed asynchronously from a separate thread to keep the app butter smooth.

Answer 2

Services is one part of a solution, but note that a service runs on the foreground thread. You would want to run your AsyncTask from the service to ensure that it continues to run on a background thread.

Personally, I would recommend against using a service in favor of the JobScheduler or if you need to support devices below API 21, Evernote's JobManager (which is also a bit easier to use). These will help you schedule your background operations at appropriate times, to minimize battery use or when the device is idle. It's important to be a good citizen when using the device's resource.

Answer 3

您必须检查服务或/和IntentServices