我正在开发智能手机/平板电脑应用程序，仅使用一个 APK，并根据屏幕大小按需加载资源，最佳设计选择似乎是通过 ACL 使用片段。
该应用程序一直运行良好，直到现在仅基于活动。这是我如何在活动中处理 AsyncTasks 和 ProgressDialogs 的模拟类，以使它们即使在屏幕旋转或在通信中发生配置更改时也能正常工作。
我不会更改清单以避免重新创建活动，我不想这样做的原因有很多，但主要是因为官方文档说它不推荐并且我到目前为止没有它，所以请不要推荐路线。
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
}
}
}
}
这段代码运行良好，我有大约 10.000 个用户没有抱怨，所以将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，它不起作用。
这是登录片段：
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 Activity 而不是从 Fragment 调用，与getLastNonConfigurationInstance(). 我在这里读过一些类似的问题，但没有答案。
我知道可能需要一些工作才能将这些东西正确组织成碎片，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，考虑到 AsyncTask 是 Fragment 的内部类，并且调用 AsyncTask.execute 的是 Fragment 本身()?