在屏幕旋转或配置更改期间保留一个 AsyncTask
我正在开发一个 Smartphone/Tablet 应用程序，只使用一个 APK，根据屏幕大小加载所需的资源，最好的设计选择似乎是通过 ACL 使用片段。
这个应用程序一直运行良好，直到现在只是基于活动。这是一个模拟类，模拟我如何处理活动中的 AsyncTasks 和 ProgressDialogs，以便在屏幕旋转或配置更改发生时仍能正常工作。
我不会为了避免重现活动而更改舱单，我不想这么做的原因有很多，但主要是因为官方文件说不推荐这么做，而且到目前为止我还没有这么做，所以请不要推荐这条路线。
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
}
}
}
}
这段代码工作得很好，我有大约10.000个用户没有抱怨，所以把这个逻辑复制到新的基于片段的设计中似乎是合乎逻辑的，但是，当然，它不工作。
以下是登录片段:
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
}
}
}
}
}
我不能使用 onRetainNonConfigurationInstance()，因为它必须从活动而不是片段中调用，getLastNonConfigurationInstance()也是如此。我在这里读到过一些类似的问题，但是没有答案。
我明白，它可能需要一些工作周围，以获得这些东西组织在片段正确，这就是说，我想维护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，显示一个 Progress sDialog，同时考虑到 AsyncTask 是片段的内部类，并且是片段本身调用 AsyncTask.execute () ？
最佳答案