fragment懒加载

/**
 * 懒加载Fragment，其子类都具有懒加载的能力
 */
public abstract class BaseFragment extends Fragment {

    protected View rootView;
    private boolean isInitView = false;
    private boolean isVisible = false;

    @Nullable
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        rootView = inflater.inflate(setContentView(), container, false);
        init();
        isInitView = true;
        isCanLoadData();
        return rootView;
    }

    @Override
    public void setUserVisibleHint(boolean isVisibleToUser) {
        super.setUserVisibleHint(isVisibleToUser);

        //isVisibleToUser这个boolean值表示:该Fragment的UI 用户是否可见，获取该标志记录下来
        if(isVisibleToUser){
            isVisible = true;
            isCanLoadData();
        }else{
            isVisible = false;
        }
    }

    private void isCanLoadData(){
        //所以条件是view初始化完成并且对用户可见
        if(isInitView && isVisible ){
            lazyLoad();

            //防止重复加载数据
            isInitView = false;
            isVisible = false;
        }
    }

    /**
     * 加载页面布局文件
     * @return
     */
    protected abstract int setContentView();

    /**
     * 让布局中的view与fragment中的变量建立起映射
     */
    protected abstract void init();

    /**
     * 加载要显示的数据
     */
    protected abstract void lazyLoad();

}

boolean netWork = NetWordUtils.isNetWork(this);
        if (!netWork){
            QueryBuilder<UserEntity> userEntityQueryBuilder = App.getDaoSession().getUserEntityDao().queryBuilder();
            UserAdapter adapter=new UserAdapter(this,userEntityQueryBuilder.list());
            recycle.setLayoutManager(new LinearLayoutManager(this));
            recycle.setAdapter(adapter);
        }