在viewpager FragmentStatePagerAdapter中恢复片段

Question

我正在使用带有FragmentStatePagerAdapter（有很多页面）的ViewPager导致内存问题。

这很有效，但是我希望能够在重新创建片段时将页面（ListFragments）恢复到原始位置。这似乎很简单，但我没有太多运气实现它。

有没有人有任何提示？

@Override
public Fragment getItem(int position) {
    // TODO Auto-generated method stub

    Fragment fragment = new PostListFragment();
    Bundle args = new Bundle();
    Map<String, String> categoryitem=categoryList.get(position);
    args.putString("slug", categoryitem.get("slug"));
    fragment.setArguments(args);
    return fragment;
}

在PostListFragment中，我调用Web服务来获取基于＆＃34; slug＆＃34;的帖子。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    Bundle bundle=this.getArguments();
    slug=bundle.getString("slug");

    Log.v("PostList Fragment of"+slug,"onCreateView");

    getPosts(slug);

    View view=inflater.inflate(R.layout.fragment_post_list, container, false);
    progressDialog = (ProgressBar)view.findViewById(R.id.progressBar);
    postRecyclerView=(RecyclerView) view.findViewById(R.id.postRecyclerview);
    postRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    postRecyclerView.removeAllViews();
    return view;
}

每次调用webservice时都在这里。我想仅针对特定的slug调用webservice一次，然后存储该slug的帖子并重新使用这些帖子而不再调用webservice。

public class MainFragment extends Fragment {

HomePagerAdapter pagerAdapter;
SlidingTabLayout slidingTabs;
ViewPager viewPager;
MyDb db;
public MainFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setRetainInstance(true);
    pagerAdapter=new HomePagerAdapter(getChildFragmentManager() ,getActivity());
}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    View view=inflater.inflate(R.layout.fragment_main, container,false);

    slidingTabs=(SlidingTabLayout) view.findViewById(R.id.sliding_tabs);
    viewPager=(ViewPager) view.findViewById(R.id.vpPager);

    viewPager.setAdapter(pagerAdapter);
    viewPager.setCurrentItem(0);
    slidingTabs.setCustomTabView(R.layout.custom_tab, R.id.title);

    db=new MyDb(getActivity());
    slidingTabs.setCustomTabColorizer(new SlidingTabLayout.TabColorizer() {

        @Override
        public int getIndicatorColor(int position) {
            // TODO Auto-generated method stub
            return getResources().getColor(R.color.red);
        }
    });

    slidingTabs.setViewPager(viewPager);
    return view;
}

}

我的FragmentPagerAdapter类

public class HomePagerAdapter extends FragmentStatePagerAdapter {

Context context;
private SharedPreferences mySharedpref;
String userId;
MyDb db;
FragmentManager mFragmentManager;

ArrayList<Map<String, String>> categoryList = new ArrayList<Map<String, String>>();

public HomePagerAdapter(FragmentManager fm, Context context) {
    super(fm);
    this.context=context;
    this.mFragmentManager = fm;
    mySharedpref = PreferenceManager.getDefaultSharedPreferences(context);
    userId=mySharedpref.getString("userId", "0");
    db=new MyDb(context);
    categoryList = db.getCategoryFromDb("30");
}

@Override
public Fragment getItem(int position) {
    // TODO Auto-generated method stub

    Fragment fragment = new PostListFragment();
    Bundle args = new Bundle();
    Map<String, String> categoryitem=categoryList.get(position);
    args.putString("slug", categoryitem.get("slug"));
    fragment.setArguments(args);
    return fragment;
}

@Override
public int getCount() {
    // TODO Auto-generated method stub
    return categoryList.size();
}

@Override
public CharSequence getPageTitle(int position) {
    // TODO Auto-generated method stub

    //  return super.getPageTitle(position);
    Map<String, String> categoryTitle=categoryList.get(position);
    return categoryTitle.get("title");

    //  return title[position];

}

}