我有一个名为HomeFragment.java的片段。这是我的应用程序打开时启动的第一个片段。在这个片段中，我有一个名为“onAsyncTaskDoInBackground”的方法，它使用JSON从服务器获取所有数据。
我要做的是使用“savedInstanceState”，这样每次重新打开“HomeFragment.java”时都不会重新下载所有数据。
示例：
用户打开应用程序并启动Homefragment.java，下载所有数据。用户转到about us页面并返回主页（Homefragment，java），再次下载所有数据。 （不应该在同一个应用程序启动时重新下载所有数据）
HomeFragment.java
public class HomeFragment extends Fragment implements OnItemClickListener, OnClickListener, MainActivity.OnLocationListener {
private View viewInflate;
DisplayImageOptions options;
ArrayList<Store> storeList;
ArrayList<News> newsList;
private ArrayList<News> arrayData;
MGAsyncTask task;
Queries q;
private Store store;
Random rand = new Random();
public HomeFragment() { }
@SuppressLint("InflateParams")
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
viewInflate = inflater.inflate(R.layout.fragment_home, null);
return viewInflate;
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
}
@Override
public void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
if(task != null)
task.cancel(true);
}
@Override
public void onViewCreated(View view, Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onViewCreated(view, savedInstanceState);
options = new DisplayImageOptions.Builder()
.showImageOnLoading(UIConfig.SLIDER_PLACEHOLDER)
.showImageForEmptyUri(UIConfig.SLIDER_PLACEHOLDER)
.showImageOnFail(UIConfig.SLIDER_PLACEHOLDER)
.cacheInMemory(true)
.cacheOnDisk(true)
.considerExifParams(true)
.bitmapConfig(Bitmap.Config.RGB_565)
.build();
storeList = new ArrayList<Store>();
newsList = new ArrayList<News>();
MainActivity main = (MainActivity) getActivity();
timer();
main.showSwipeProgress();
main.getDebugKey();
q = main.getQueries();
if(MGUtilities.isLocationEnabled(getActivity())) {
if(MainActivity.location == null) {
main.setOnLocationListener(this);
}
else {
Handler h = new Handler();
h.postDelayed(new Runnable() {
@Override
public void run() {
getData();
arrayData = q.getNews();
}
}, Config.DELAY_SHOW_ANIMATION);
}
}
else {
main.setOnLocationListener(this);
}
}
public void getData() {
task = new MGAsyncTask(getActivity());
task.setMGAsyncTaskListener(new OnMGAsyncTaskListener() {
@Override
public void onAsyncTaskProgressUpdate(MGAsyncTask asyncTask) {
}
@Override
public void onAsyncTaskPreExecute(MGAsyncTask asyncTask) {
asyncTask.dialog.hide();
}
@Override
public void onAsyncTaskPostExecute(MGAsyncTask asyncTask) {
// TODO Auto-generated method stub
arrayData = q.getNews();
if(!MGUtilities.hasConnection(getActivity())) {
ArrayList<Store> stores = q.getStoresFeatured();
ArrayList<News> news = q.getNews();
if (Config.HOME_STORE_FEATURED_COUNT != -1 && Config.RANK_STORES_ACCORDING_TO_NEARBY) {
Log.v("myApp", "STORE SLIDER THING - STORE SLIDER THING - STORE SLIDER THING - STORE SLIDER THING - STORE SLIDER THING - STORE SLIDER THING - " );
int storeCount = stores.size() < Config.HOME_STORE_FEATURED_COUNT ?
stores.size() : Config.HOME_STORE_FEATURED_COUNT;
if (MainActivity.location != null) {
for (Store store : stores) {
Location locStore = new Location("Store");
locStore.setLatitude(store.getLat());
locStore.setLongitude(store.getLon());
double userDistanceFromStore = MainActivity.location.distanceTo(locStore) / 1000;
store.setDistance(userDistanceFromStore);
}
Collections.sort(stores, new Comparator<Store>() {
@Override
public int compare(Store store, Store t1) {
if (store.getDistance() < t1.getDistance())
return -1;
if (store.getDistance() > t1.getDistance())
return 1;
return 0;
}
});
}
storeList = new ArrayList<Store>();
for (int x = 0; x < storeCount; x++) {
storeList.add(stores.get(x));
}
} else {
storeList = stores;
}
if (Config.HOME_NEWS_COUNT != -1 && Config.RANK_STORES_ACCORDING_TO_NEARBY) {
Log.v("myApp", "NEWS SLIDER THING - NEWS SLIDER THING - NEWS SLIDER THING - NEWS SLIDER THING - NEWS SLIDER THING - NEWS SLIDER THING - " );
int newsCount = news.size() < Config.HOME_NEWS_COUNT ? news.size() : Config.HOME_NEWS_COUNT;
newsList = new ArrayList<News>();
for (int x = 0; x < newsCount; x++) {
newsList.add(news.get(x));
}
} else {
newsList = news;
}
}
MainActivity main = (MainActivity) getActivity();
main.hideSwipeProgress();
}
@Override
public void onAsyncTaskDoInBackground(MGAsyncTask asyncTask) {
// TODO Auto-generated method stub
if( MGUtilities.hasConnection(getActivity()) && MainActivity.location != null) {
try {
UserAccessSession accessSession = UserAccessSession.getInstance(getActivity());
String strUrl = "";
if(accessSession.getFilterDistance() == 0) {
Log.v("myApp", "STRURL - STRURL - STRURL - STRURL - STRURL - STRURL - STRURL - STRURL - STRURL - STRURL - " );
if(MGUtilities.hasConnection(getActivity())) {
try {
strUrl = String.format("%s?api_key=%s",
Config.GET_CATEGORIES_JSON_URL,
Config.API_KEY);
DataParser parser = new DataParser();
Data data = parser.getData(strUrl);
MainActivity main = (MainActivity) getActivity();
if (main == null)
return;
Queries q = main.getQueries();
if (data == null)
return;
q.deleteTable("categories");
if (data.getCategories() != null && data.getCategories().size() > 0) {
Log.v("myApp", "CATEGORYS - CATEGORYS - CATEGORYS - CATEGORYS - CATEGORYS - CATEGORYS - CATEGORYS - CATEGORYS - " );
for (Category cat : data.getCategories()) {
q.insertCategory(cat);
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
strUrl = String.format("%s?api_key=%s&lat=%f&lon=%f&radius=%f&news_count=%d&featured_count=%d&default_store_count_to_find_distance=%d",
Config.GET_HOME_STORES_NEWS_JSON_URL,
Config.API_KEY,
MainActivity.location.getLatitude(),
MainActivity.location.getLongitude(),
accessSession.getFilterDistance(),
Config.HOME_NEWS_COUNT,
Config.HOME_FEATURED_COUNT,
Config.DEFAULT_STORE_COUNT_TO_FIND_DISTANCE);
}
else {
strUrl = String.format("%s?api_key=%s&lat=%f&lon=%f&radius=%f&news_count=%d&default_store_count_to_find_distance=%d",
Config.GET_HOME_STORES_NEWS_JSON_URL,
Config.API_KEY,
MainActivity.location.getLatitude(),
MainActivity.location.getLongitude(),
accessSession.getFilterDistance(),
Config.HOME_NEWS_COUNT,
Config.DEFAULT_STORE_COUNT_TO_FIND_DISTANCE);
}
DataParser parser = new DataParser();
Data data = parser.getData(strUrl);
MainActivity main = (MainActivity) getActivity();
if (main == null)
return;
Queries q = main.getQueries();
if (data == null)
return;
if(Config.AUTO_ADJUST_DISTANCE) {
if(data.getMax_distance() > 0) {
UserAccessSession.getInstance(getActivity()).setFilterDistanceMax(data.getMax_distance());
}
if(UserAccessSession.getInstance(getActivity()).getFilterDistance() == 0) {
UserAccessSession.getInstance(getActivity()).setFilterDistance(data.getDefault_distance());
}
}
if (data.getStores() != null && data.getStores().size() > 0) {
Log.v("myApp", "ENTERED THE IF - ENTERED THE IF - ENTERED THE IF - ENTERED THE IF - ENTERED THE IF" );
int storeCount = data.getStores().size() < Config.HOME_STORE_FEATURED_COUNT ?
data.getStores().size() : Config.HOME_STORE_FEATURED_COUNT;
int x = 0;
for (Store store : data.getStores()) {
Location locStore = new Location("Store");
locStore.setLatitude(store.getLat());
locStore.setLongitude(store.getLon());
double userDistanceFromStore = MainActivity.location.distanceTo(locStore) / 1000;
store.setDistance(userDistanceFromStore);
if (userDistanceFromStore < 50){
Log.v("myApp", "STORE - STORE - STORE - STORE - STORE - STORE - STORE - STORE - STORE - STORE - STORE- STORE" );
q.deleteStore(store.getStore_id());
q.insertStore(store);
if(x < storeCount) {
Log.v("myApp", "if(x < storeCount) - if(x < storeCount)- if(x < storeCount)- if(x < storeCount)- if(x < storeCount)- if(x < storeCount)" );
if (store.getFeatured() == 3 ) {
storeList.add(store);
x += 1;
}
}
if (store.getPhotos() != null && store.getPhotos().size() > 0) {
Log.v("myApp", "PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS - PHOTOS" );
for (Photo photo : store.getPhotos()) {
q.deletePhoto(photo.getPhoto_id());
q.insertPhoto(photo);
}
}
}}
if (data.getNews() != null && data.getNews().size() > 0) {
Log.v("myApp", "NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS - NEWS" );
int newsCount = data.getNews().size() < Config.HOME_NEWS_COUNT
? data.getNews().size() : Config.HOME_NEWS_COUNT;
x = 0;
for (News news : data.getNews()) {
q.deleteNews(news.getNews_id());
q.insertNews(news);
if(x < newsCount) {
newsList.add(news);
x += 1;
}
}
}}
try {
strUrl = "";
strUrl = String.format("%s?api_key=%s",
Config.GET_NEWS_JSON_URL,
Config.API_KEY);
Log.v("myApp", "NEWS UPDATE - NEWS UPDATE - NEWS UPDATE - NEWS UPDATE - NEWS UPDATE - NEWS UPDATE - NEWS UPDATE " );
parser = new DataParser();
data = parser.getData(strUrl);
main = (MainActivity) getActivity();
if (main == null)
return;
if (data == null)
return;
q.deleteTable("news");
if (data.getNews() != null && data.getNews().size() > 0) {
for (News news : data.getNews()) {
q.insertNews(news);
}
}
} catch (Exception e) {
e.printStackTrace();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
});
task.execute();
}
@Override
public void onDestroyView() {
super.onDestroyView();
if (viewInflate != null) {
ViewGroup parentViewGroup = (ViewGroup) viewInflate.getParent();
if (parentViewGroup != null) {
MGSlider slider = (MGSlider) viewInflate.findViewById(R.id.slider);
slider.pauseSliderAnimation();
parentViewGroup.removeAllViews();
}
}
handler.removeCallbacks(runnable);
if(task != null)
task.cancel(true);
}
Handler handler = new Handler();
int apple = 0;
Runnable runnable = new Runnable() {
public void run() {
if(apple < 5) {
timer();
}
}
};
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
MGSlider slider = (MGSlider) viewInflate.findViewById(R.id.slider);
slider.stopSliderAnimation();
switch(v.getId()) { }
}
@Override
public void onResume() {
// TODO Auto-generated method stub
super.onResume();
MGSlider slider = (MGSlider) viewInflate.findViewById(R.id.slider);
slider.resumeSliderAnimation();
}
@Override
public void onPause() {
// TODO Auto-generated method stub
super.onPause();
MGSlider slider = (MGSlider) viewInflate.findViewById(R.id.slider);
slider.pauseSliderAnimation();
}
@Override
public void onLocationChanged(Location prevLoc, Location currentLoc) {
MainActivity main = (MainActivity) getActivity();
main.setOnLocationListener(null);
getData();
}
}
答案 0 :(得分：0)
你可以这样做。
private View viewFragment;
private ArrayList<MyClass> list = new ArrayList<>();
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
viewFragment = inflater.inflate(R.layout.fragment_layout, container, false);
initIds();
if (savedInstanceState == null) {
// get all data and saved in list.
} else {
// use saved list or other data here...
list = savedInstanceState.getParcelableArrayList("arraylist");
setListAdapter(list);
}
return viewFragment;
}
@Override
public void onSaveInstanceState(Bundle outState) {
super.onSaveInstanceState(outState);
outState.putParcelableArrayList("arraylist", list);
}