在viewpager中禁用片段重新加载数据

Question

我在我的 Android 项目中使用 ViewPager，我使用FragmentStatePagerAdapter来设置页面。

class MyPageAdapter extends FragmentStatePagerAdapter {
    List<Fragment> mList = new ArrayList<>();

    public MyPageAdapter(FragmentManager fm) {
        super(fm);
        this.init();
    }

    private void init() {
        mList.add(new FragmentOne());
        mList.add(new FragmentTwo());
        mList.add(new FragmentThree());
            ....
    }

    @Override
    public Fragment getItem(int position) {
        return mList.get(position);
    }
}

并且对于每个Fragment数据将在创建视图后从服务器加载，如下所示：

public  class FragmentOne extends Fragment {
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View v = inflater.inflate(getViewResourceId(), container, false);
        ButterKnife.bind(this, v);
        setRetainInstance(true);

        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(getContext());
        mRecycleView.setLayotManager(linearLayoutManager);

        endlessRecyclerViewScrollListener = new EndlessRecyclerViewScrollListener((LinearLayoutManager) mRecycleView.getLayoutManager()) {
            @Override
            public void onLoadMore(int page, int totalItemsCount, RecyclerView view) {
                loadByPage(page);
            }
        };
        mRecycleView.addOnScrollListener(endlessRecyclerViewScrollListener);
        return v;
    }
    @Override
    public void onActivityCreated(@Nullable Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);

        mAdapter = createAdapter();
        mRecycleView.setAdapter(mAdapter);
        loadByPage(1); // load data from server
    }
}

如图所示， Fragment包含一个无尽的回收器视图。

到现在为止还挺好。 但是一旦我更改了选定的视图页面，我发现每次都会重新加载数据。 例如，我在FragmentOne滚动了 3 页，然后更改为FragmentTwo ，当我更改为FragmentOne ， FragmentOne将尝试加载第 1 页的数据。

有没有可能避免这种情况？

Answer 1

你可以做这样的事情：

private boolean isDataCalled = true;
private List<ItemModel> itemModelList;

进而

 if (isDataCalled){
        loadByPage(1); //  Initialize itemModelList in this method
        setItemAdapter(itemModelList);      
        isDataCalled = false;
    }else {
        setItemAdapter(itemModelList);
    }

setItemAdapter 方法

private void setItemAdapter(List<ItemModel> itemModelList){
    mAdapter = createAdapter(itemModelList);
    mRecycleView.setAdapter(mAdapter);
}