這是一個星期我試圖解決這個問題成功.請幫我.
我使用帶有viewpager的標簽導航.這是我放置標簽和FragmentPagerAdapter類的類：
public class Detail extends SherlockFragmentActivity { ViewPager mViewPager; TabsAdapter mTabsAdapter; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); ... ActionBar bar = getSupportActionBar(); bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); bar.setDisplayOptions(0, ActionBar.DISPLAY_SHOW_TITLE); mViewPager = (ViewPager)findViewById(R.id.pager); // Add the tabs mTabsAdapter = new TabsAdapter(this, bar, mViewPager); mTabsAdapter.addTab(bar.newTab().setText(R.string.filmtab), FragmentFilm.class, null); mTabsAdapter.addTab(bar.newTab().setText(R.string.cinematab), FragmentCinema.class, null); mTabsAdapter.addTab(bar.newTab().setText(R.string.dintornitab), FragmentPdi.class, null); if (savedInstanceState != null) { bar.setSelectedNavigationItem(savedInstanceState.getInt("tab")); } } @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); outState.putInt("tab", getSupportActionBar().getSelectedNavigationIndex()); } public static class TabsAdapter extends FragmentPagerAdapter implements ViewPager.OnPageChangeListener, ActionBar.TabListener { private final Context mContext; private final ActionBar mBar; private final ViewPager mViewPager; private final ArrayList<TabInfo> mTabs = new ArrayList<TabInfo>(); static final class TabInfo { private final Class<?> clss; private final Bundle args; TabInfo(Class<?> _class, Bundle _args) { clss = _class; args = _args; } } public TabsAdapter(Detail activity, ActionBar bar, ViewPager pager) { super(activity.getSupportFragmentManager()); mContext = activity; mBar = bar; mViewPager = pager; mViewPager.setAdapter(this); mViewPager.setOnPageChangeListener(this); } public void addTab(ActionBar.Tab tab, Class<? extends Fragment> clss, Bundle args) { TabInfo info = new TabInfo(clss, args); tab.setTag(info); tab.setTabListener(this); mTabs.add(info); mBar.addTab(tab); notifyDataSetChanged(); } @Override public int getCount() { return mTabs.size(); } @Override public Fragment getItem(int position) { TabInfo info = mTabs.get(position); return Fragment.instantiate(mContext, info.clss.getName(), info.args); } @Override public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) { } @Override public void onPageSelected(int position) { mBar.setSelectedNavigationItem(position); } @Override public void onPageScrollStateChanged(int state) { } @Override public void onTabSelected(Tab tab, FragmentTransaction ft) { Object tag = tab.getTag(); for (int i=0; i<mTabs.size(); i ) { if (mTabs.get(i) == tag) { mViewPager.setCurrentItem(i); } } } @Override public void onTabUnselected(Tab tab, FragmentTransaction ft) { } @Override public void onTabReselected(Tab tab, FragmentTransaction ft) { } }}3個片段類都是一樣的,我這里只復制一個;
在片段類中我使用異步任務來下載我需要放在視圖中的數(shù)據(jù),我在onActivityCreated方法中執(zhí)行此操作：
public class FragmentFilm extends SherlockFragment{ private Detail act; private DetailedRec detail_film; private View view; private String a; @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { setRetainInstance(true); view = inflater.inflate(R.layout.tab_film_info, container, false); return view; } /* @Override public void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); }*/ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); act = (Detail) getActivity(); } @Override public void onActivityCreated(Bundle savedInstanceState) { super.onActivityCreated(savedInstanceState); new DownloadFilmDetailAsyncTask().execute(); } private class DownloadFilmDetailAsyncTask extends AsyncTask<Void, DetailedRec, Void> { @Override protected void onPreExecute() { super.onPreExecute(); } @Override protected void onPostExecute(Void result) { super.onPostExecute(result); ProgressBar prBar = (ProgressBar)getView().findViewById(R.id.progressbar_film); prBar.setVisibility(View.GONE); ScrollView lay = (ScrollView)getView().findViewById(R.id.tab_filmsummary); lay.setVisibility(View.VISIBLE); } @Override protected Void doInBackground(Void... params) { try { String locale = getResources().getConfiguration().locale.getDisplayName(); JSONObject objSend = new JSONObject(); objSend.put("idFilm", act.getIdFilm()); objSend.put("cinemaId",act.getIdCinema()); int ind = locale.indexOf("("); String locale_send = locale.substring(0, ind-1); objSend.put("locale", locale_send); ArrayList<String> otherCin = new ArrayList<String>(Arrays.asList(act.getOtherCinemas())); JSONArray othCin = new JSONArray(otherCin); objSend.put("otherCinemas", othCin ); JSONObject jsonObject = sendAndGetJSONObject(JSON_SERVER "JsonServer?op=getFilmbyId",objSend); DetailedRec detail_rec = new DetailedRec(); //FILM detail_rec.setFilmId(jsonObject.getString("filmId")); detail_rec.setName(jsonObject.getString("name")); detail_rec.setImageUrl(jsonObject.getString("imageUrl").replace("640", "80")); detail_rec.setActors(jsonObject.getString("actors")); detail_rec.setGenre(jsonObject.getString("genre")); detail_rec.setDirector(jsonObject.getString("director")); detail_rec.setPlot(jsonObject.getString("plot")); detail_rec.setYear(jsonObject.getString("year")); detail_rec.setDuration(jsonObject.getString("duration")); detail_rec.setTrailer(jsonObject.getString("trailer")); detail_rec.setRating(jsonObject.getString("rating")); detail_film = detail_rec; publishProgress(detail_rec); } catch (IOException ignored) { } catch (JSONException ignored) { } return null; } @Override protected void onProgressUpdate(DetailedRec... values) { for (final DetailedRec detail_rec : values) { updateViews(detail_rec); } } private JSONObject getJSONObject(String url) throws IOException, MalformedURLException, JSONException { HttpURLConnection conn = (HttpURLConnection) new URL(url).openConnection(); InputStream in = conn.getInputStream(); try { StringBuilder sb = new StringBuilder(); BufferedReader r = new BufferedReader(new InputStreamReader(new DoneHandlerInputStream(in),"WINDOWS_1252")); for (String line = r.readLine(); line != null; line = r.readLine()) { sb.append(line); } return new JSONObject(sb.toString()); } finally { in.close(); } } private JSONObject sendAndGetJSONObject(String url,JSONObject request) throws IOException, MalformedURLException, JSONException { HttpClient client = new DefaultHttpClient(); HttpConnectionParams.setConnectionTimeout(client.getParams(), 10000); //Timeout Limit InputStream in=null; try{ HttpPost post = new HttpPost(url); StringEntity se = new StringEntity(request.toString()); se.setContentType((Header) new BasicHeader(HTTP.CONTENT_TYPE, "application/json")); post.setEntity(se); HttpResponse response = client.execute(post); HttpEntity entity = response.getEntity(); in = entity.getContent(); StringBuilder sb = new StringBuilder(); BufferedReader r = new BufferedReader(new InputStreamReader(new DoneHandlerInputStream(in),"WINDOWS_1252")); for (String line = r.readLine(); line != null; line = r.readLine()) { sb.append(line); } return new JSONObject(sb.toString()); }catch(Exception e){ } finally { in.close(); } return null; } } private void updateViews(final DetailedRec detail_rec){ //FILM TextView filmName = (TextView) getView().findViewById(R.id.movieTitle); filmName.setText(detail_rec.getName().trim()); TextView actors = (TextView) getView().findViewById(R.id.movieActor); actors.setText(detail_rec.getActors().trim()); TextView genre = (TextView) getView().findViewById(R.id.movieGenre); genre.setText(detail_rec.getGenre().trim()); TextView director = (TextView) getView().findViewById(R.id.movieDirector); director.setText(detail_rec.getDirector().trim()); TextView plot = (TextView) getView().findViewById(R.id.moviePlot); plot.setText(detail_rec.getPlot().trim()); TextView year = (TextView) getView().findViewById(R.id.movieYear); year.setText(detail_rec.getYear().trim()); TextView duration = (TextView) getView().findViewById(R.id.movieDuration); duration.setText(detail_rec.getDuration().trim()); ImageView image = (ImageView) getView().findViewById(R.id.moviePoster); new DownloadImagesTask(detail_rec.getImageUrl().trim().replace("80", "100")).execute(image); //image.setImageBitmap(downloadBitmap(detail_rec.getImageUrl().trim().replace("80", "100"))); //Rating if(detail_rec.getRating().compareTo("N/A")!=0){ RatingBar rateBar = (RatingBar)getView().findViewById(R.id.MovieRatingBar); rateBar.setRating(Float.parseFloat(detail_rec.getRating())); } //Trailer Button trailer = (Button)getView().findViewById(R.id.trailer); if(detail_rec.getTrailer().compareTo("")!=0){ trailer.setVisibility(View.VISIBLE); trailer.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { int index = detail_rec.getTrailer().indexOf("v="); String videoId=""; if(index!=-1){ videoId = detail_rec.getTrailer().substring(index 2); //"Fee5vbFLYM4"; Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse("vnd.youtube:" videoId)); intent.putExtra("VIDEO_ID", videoId); startActivity(intent); } } }); } }}好的,在我的應用程序中,我希望片段加載一次.我解釋得這么好：
當我啟動Detail類時,片段類是istantiate并且所有3個片段中的AsyncTask開始,現(xiàn)在當用戶從一個選項卡切換到另一個選項卡時我希望未選中選項卡中的片段不會丟失數(shù)據(jù)和視圖,因為現(xiàn)在當我從一個選項卡切換到另一個選項卡,然后返回第一個重新創(chuàng)建的選項卡,再次調(diào)用onActivityCreated方法！
請幫助我,我在所有地方搜索,但我沒有找到解決方案！
附：我使用SherlockActionBar,我不知道id是否相關(guān).對不起,我的英語不好
謝謝
解決方法:
在實例化ViewPager之后,添加它
mViewPager = (ViewPager)findViewById(R.id.pager);mViewPager.setOffscreenPageLimit(3);應該這樣做！
來源：https://www.icode9.com/content-4-355651.html