Loader framework and activity lifecycle

问题

I really like loaders and their benefits. But i meet a problem which i don't know how to solve. In my activity i use AsyncTaskLoader to load some data from database and provide cursor to the onLoadFinished(Loader<Cursor> loader, Cursor cursor) method which is implemented by activity. Problem is that onLoadFinished() does not called when activity is in onStop() state (not finishing()) e.g. incomming call occure.

    @Override
protected void onCreate(Bundle bundle) {
    super.onCreate(bundle);

    mActionBar.setDisplayShowTitleEnabled(false);
    mActionBar.setDisplayHomeAsUpEnabled(true);

    if (bundle != null) {
        mFilter = FilterParameters.restoreFromBundle(bundle);
    } else {
        mFilter = new FilterParameters();
    }
    setupNavigationMode();
    loadData();
}


private void loadData() {
     getSupportLoaderManager().initLoader(0, null, this).forceLoad();
}

In loadInBackground() i just simulate some work in background

    private static class GisObjectDatabaseLoader extends AsyncTaskLoader<Cursor> {
    public GisObjectDatabaseLoader(Context context) {
        super(context);
    }

    @Override
    public Cursor loadInBackground() {
        int i = 10;
        while (i > 0) {
            Log.d(GisObjectDatabaseLoader.class.getSimpleName(), "TICK #" + (10 - i));
            try {
                Thread.sleep(1000);
                i--;
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
        return null;
    }
}
@Override
public Loader<Cursor> onCreateLoader(int arg0, Bundle arg1) {
    Fragment f = getSupportFragmentManager().findFragmentByTag(ProgressDialogFragment.TAG);
    if (f == null)
        new ProgressDialogFragment().show(getSupportFragmentManager(), ProgressDialogFragment.TAG);
    Log.d(GeneralMapActivity.class.getSimpleName(), "SHOW PROGR");
    return new GisObjectDatabaseLoader(this);
}

@Override
public void onLoadFinished(Loader<Cursor> arg0, Cursor arg1) {
    Fragment f = getSupportFragmentManager().findFragmentByTag(ProgressDialogFragment.TAG);
    if (f != null) {
        ((ProgressDialogFragment) f).dismissAllowingStateLoss();
    }
    Log.d(GeneralMapActivity.class.getSimpleName(), "CANCEL PROGR");
}

Loader still working while activity is stopped and 'ticks' to the LogCat. I have looked in to AsyncTaskLoader source

  void dispatchOnLoadComplete(LoadTask task, D data) {
    if (mTask != task) {
        if (DEBUG) Slog.v(TAG, "Load complete of old task, trying to cancel");
        dispatchOnCancelled(task, data);
    } else {
        if (isAbandoned()) {
            // This cursor has been abandoned; just cancel the new data.
            onCanceled(data);
        } else {
            mLastLoadCompleteTime = SystemClock.uptimeMillis();
            mTask = null;
            if (DEBUG) Slog.v(TAG, "Delivering result");
            deliverResult(data);
        }
    }
}

Does it mean that I should manually track the loader state when an activity comes to foreground and restart it: if the loader is cancelled and data is still not published (i.e. do the same work one more time)? Is there any way around this problem?

来源：https://stackoverflow.com/questions/17588511/loader-framework-and-activity-lifecycle

标签

android

android-activity

android-loader