Android碎片。在屏幕旋转或配置更改期间保留AsyncTask

我正在开发一款智能手机/平板电脑应用程序，使用一个APK，在需要时根据屏幕大小加载资源，最佳设计选择似乎是通过ACL使用Fragment。

这个应用程序一直运行良好，只基于活动。以下是我在活动中处理AsyncTasks和ProgressDialogs的模拟类，以便在通信过程中屏幕旋转或配置更改时仍能工作。

我不会更改清单以避免重新创建活动，有很多原因我不想这样做，但主要是因为官方文档说这不被推荐，并且我到目前为止已经成功地管理了它，所以请不要推荐这种方法。

public class Login extends Activity {

    static ProgressDialog pd;
    AsyncTask<String, Void, Boolean> asyncLoginThread;

    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.login);
        //SETUP UI OBJECTS
        restoreAsyncTask();
    }

    @Override
    public Object onRetainNonConfigurationInstance() {
        if (pd != null) pd.dismiss();
        if (asyncLoginThread != null) return (asyncLoginThread);
        return super.onRetainNonConfigurationInstance();
    }

    private void restoreAsyncTask();() {
        pd = new ProgressDialog(Login.this);
        if (getLastNonConfigurationInstance() != null) {
            asyncLoginThread = (AsyncTask<String, Void, Boolean>) getLastNonConfigurationInstance();
            if (asyncLoginThread != null) {
                if (!(asyncLoginThread.getStatus()
                        .equals(AsyncTask.Status.FINISHED))) {
                    showProgressDialog();
                }
            }
        }
    }

    public class LoginThread extends AsyncTask<String, Void, Boolean> {
        @Override
        protected Boolean doInBackground(String... args) {
            try {
                //Connect to WS, recieve a JSON/XML Response
                //Place it somewhere I can use it.
            } catch (Exception e) {
                return true;
            }
            return true;
        }

        protected void onPostExecute(Boolean result) {
            if (result) {
                pd.dismiss();
                //Handle the response. Either deny entry or launch new Login Succesful Activity
            }
        }
    }
}

这段代码很好用，在大约1万个用户中没有出现任何问题，所以直接将此逻辑复制到新的基于碎片的设计中似乎是合理的，但是，当然，它不起作用了。

这是LoginFragment:

public class LoginFragment extends Fragment {

    FragmentActivity parentActivity;
    static ProgressDialog pd;
    AsyncTask<String, Void, Boolean> asyncLoginThread;

    public interface OnLoginSuccessfulListener {
        public void onLoginSuccessful(GlobalContainer globalContainer);
    }

    public void onSaveInstanceState(Bundle outState){
        super.onSaveInstanceState(outState);
        //Save some stuff for the UI State
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setRetainInstance(true);
        //If I setRetainInstance(true), savedInstanceState is always null. Besides that, when loading UI State, a NPE is thrown when looking for UI Objects.
        parentActivity = getActivity();
    }

    @Override
    public void onAttach(Activity activity) {
        super.onAttach(activity);
        try {
            loginSuccessfulListener = (OnLoginSuccessfulListener) activity;
        } catch (ClassCastException e) {
            throw new ClassCastException(activity.toString() + " must implement OnLoginSuccessfulListener");
        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        RelativeLayout loginLayout = (RelativeLayout) inflater.inflate(R.layout.login, container, false);
        return loginLayout;
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        //SETUP UI OBJECTS
        if(savedInstanceState != null){
            //Reload UI state. Im doing this properly, keeping the content of the UI objects, not the object it self to avoid memory leaks.
        }
    }

    public class LoginThread extends AsyncTask<String, Void, Boolean> {
            @Override
            protected Boolean doInBackground(String... args) {
                try {
                    //Connect to WS, recieve a JSON/XML Response
                    //Place it somewhere I can use it.
                } catch (Exception e) {
                    return true;
                }
                return true;
            }

            protected void onPostExecute(Boolean result) {
                if (result) {
                    pd.dismiss();
                    //Handle the response. Either deny entry or launch new Login Succesful Activity
                }
            }
        }
    }
}

由于必须从Activity而不是Fragment中调用onRetainNonConfigurationInstance()和getLastNonConfigurationInstance()，因此我无法使用它们。我已经阅读了一些类似的问题，但没有答案。

我理解在片段中正确组织这些内容可能需要一些解决方法，但是，我希望保持相同的基本设计逻辑。

在配置更改期间保留AsyncTask的正确方法是什么？如果它仍在运行，则显示进度对话框，考虑到AsyncTask是片段的内部类，而且是片段本身调用AsyncTask.execute()的呢？