关于多个fragment，多个网络请求优雅懒加载处理（每个fra

关于多个fragment+tabhost+viewpager，多个网络请求优雅懒加载处理（每个fragment第一次请求玩数据，后面默认不再加载，除非用户主动刷新）

解决问题：

1.ViewPager的懒加载模式为了让切换更加流畅，但是会多预加载的Fragment需要的数据进行网络请求，当多个Fragment都存在大量数据的时候，容易因为队列中请求较多导致卡顿，也浪费流量。

2.频繁切换ViewPager造成过多的网络请求。

3.在UI还没有渲染完成的时候请求数据，导致空指针异常。

解决方案：抽象基类的创建

public abstract class BasePageFragment extends Fragment {
protected boolean isViewInitiated;
protected boolean isVisibleToUser;
protected boolean isDataInitiated;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
}

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);
    isViewInitiated = true;
    prepareFetchData();
}

@Override
public void setUserVisibleHint(boolean isVisibleToUser) {
    super.setUserVisibleHint(isVisibleToUser);
    this.isVisibleToUser = isVisibleToUser;
    prepareFetchData();
}

public abstract void fetchData();

public boolean prepareFetchData() {
    return prepareFetchData(false);
}

public boolean prepareFetchData(boolean forceUpdate) {
    if (isVisibleToUser && isViewInitiated && (!isDataInitiated || forceUpdate)) {
        fetchData();
        isDataInitiated = true;
        return true;
    }
    return false;
}

}

public class Item1Fragment extends BasePageFragment {

private XRecyclerView xRecyclerView;
private ItemAdapter adapter = null;

private List<TaskDetail> lists;

public Item1Fragment() {
}


private void initView(View view) {

xRecyclerView = view.findViewById(R.id.recyclerview);
xRecyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
initData();
adapter = new ItemAdapter(getContext(),lists);
xRecyclerView.setAdapter(adapter);

    adapter.setOnClickItemListener(new ItemAdapter.OnClickItemListener() {
        @Override
        public void onClick(TaskDetail taskDetail) {
            Intent intent = new Intent(getActivity(), TaskDetailsActivity.class);
            switch (taskDetail.getType()){
                case "1"://待派件
                    break;
                case "2"://待回收
                    break;
                case "3"://代送回执包
                    break;
            }
            startActivity(intent);
        }
    });

}

@Override
public void fetchData() {
    initView(view)//初始化
    mPresenter.getSendNumDate();//网络请求
}

@Nullable
@Override
public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_item1,null);
    return view;
}

}
原文地址:https://blog.csdn.net/qq_20369621/article/details/91457606