我正在开发一个智能手机/平板电脑应用程序，仅使用一个APK，并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。
到目前为止，此应用程序一直运行良好，仅基于活动。这是一个模拟类，它说明了我如何处理“活动”中的AsyncTasks和ProgressDialogs以便即使在屏幕旋转或通信过程中发生配置更改时也能正常工作的情况。
我不会更改清单以避免活动的重演，我有很多理由不愿意这样做，但主要是因为官方文档说不建议这样做，而且到目前为止，我已经设法不使用它了，所以请不要建议路线。
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
}
}
}
}
这段代码可以正常工作，我有大约10.000个用户，没有任何抱怨，因此仅将逻辑复制到新的基于片段的设计中似乎很合逻辑，但是，当然这是行不通的。
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
}
}
}
}
}
我不能使用，onRetainNonConfigurationInstance()因为它必须从Activity而不是Fragment中调用，这与相同getLastNonConfigurationInstance()。我在这里读了一些类似的问题，没有答案。
我知道，可能需要一些工作才能使这些内容正确地组织成碎片，也就是说，我想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，则显示一个progressDialog，同时考虑到AsyncTask是Fragment的内部类，而调用AsyncTask.execute的是Fragment本身。 （）？