android懒加载fragment实现

偶遇一个不错的懒加载fragment实现，仅记录。

public abstract class LazyFragment extends BaseFragment {

    protected boolean isViewInitiated; //控件是否初始化完成
    protected boolean isVisibleToUser; //页面是否可见
    protected boolean isDataInitiated; //数据是否加载


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

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

    public abstract void loadData();


    protected void prepareFetchData(boolean forceUpdate) {
        if (isVisibleToUser && isViewInitiated && (!isDataInitiated || forceUpdate)) {
            loadData();
            isDataInitiated = true;
        }
    }
}