学习使用鸿蒙基础控件，实现类似新闻类app顶部tab效果。
先上demo图：

image.png

image.png

实现步骤：

1、使用模板创建项目，自带开屏页；

2、修改main布局文件，添加tabList，pageSlider控件，tabList相关属性设置，也可在代码中实现；

<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
    xmlns:ohos="http://schemas.huawei.com/res/ohos"
    ohos:height="match_parent"
    ohos:width="match_parent"
    ohos:orientation="vertical">

    <TabList
        ohos:id="$+id:title_tabs"
        ohos:height="48vp"
        ohos:width="match_parent"
        ohos:background_element="$color:copyright_text_color"
        ohos:fixed_mode="false"
        ohos:normal_text_color="#ffffff"
        ohos:orientation="horizontal"
        ohos:selected_tab_indicator_color="#ff0000"
        ohos:selected_tab_indicator_height="2vp"
        ohos:selected_text_color="#ff0000"
        ohos:tab_margin="5vp"
        ohos:text_alignment="center"
        ohos:text_size="18fp"
        />

    <PageSlider
        ohos:id="$+id:pager"
        ohos:height="match_parent"
        ohos:width="match_parent"
        />

</DirectionalLayout>

3、鸿蒙支持各类数据xml定义，与安卓类似，数组资源文件定义（base/element/strarray.json）；

{
  "strarray": [
    {
      "name": "tab_title",
      "value": [
        {
          "value": "推荐"
        },
        {
          "value": "热点"
        },
        {
          "value": "NBA"
        },
        {
          "value": "美图"
        },
        {
          "value": "疫情"
        },
        {
          "value": "本地"
        },
        {
          "value": "军事"
        },
        {
          "value": "投资"
        },
        {
          "value": "金融"
        }
      ]
    }
  ]
}

4、开发实现，代码较为基础，不做多解释，如有疑问或想法可在评论区交流；

原本期望使用fraction+pageSlider实现整体页面切换，查阅官方资料，暂不支持。无奈用component代替fraction。

    @Override
    public void onStart(Intent intent) {
        super.onStart(intent);
        super.setUIContent(ResourceTable.Layout_ability_main);

        initView();
        initData();
    }

//初始化控件
 private void initView() {
        tabList = (TabList) findComponentById(ResourceTable.Id_title_tabs);
        pageSlider = (PageSlider) findComponentById(ResourceTable.Id_pager);

        tabList.addTabSelectedListener(this);
        pageSlider.addPageChangedListener(this);
    }

// tab与page数据初始化
private void initData() {
        try {
            String[] tabsTitle = getResourceManager().getElement(ResourceTable.Strarray_tab_title).getStringArray();
            for (String title: tabsTitle){
                TabList.Tab tab = tabList.new Tab(getContext()); 
                tab.setText(title);
                tabList.addTab(tab);
            }
            tabList.selectTabAt(0);  //选中0位置

            pageSlider.setProvider(new MainPagerAdapter(initPageSliderViewData())); 
            pageSlider.setCurrentPage(0);
            pageSlider.setReboundEffect(true);
            pageSlider.setCentralScrollMode(true);
        } catch (IOException | NotExistException | WrongTypeException e) {
            e.printStackTrace();
        }
    }

    private ArrayList<Component> initPageSliderViewData() {
        int pageSize = tabList.getTabCount();
        ArrayList<Component> pages = new ArrayList<>();
       ViewCreateHelper viewCreateHelper = new ViewCreateHelper(getContext());
        for (int i = 0; i < pageSize; i++) {
            pages.add(viewCreateHelper.createView(tabList.getTabAt(i).getText()));
        }
        return pages;
    }

①PageSlider适配器，使用方式与viewPager类似；

public class MainPagerAdapter extends PageSliderProvider {

    private List<Component> pages;


    public MainPagerAdapter(ArrayList<Component> pages) {
        this.pages = pages;
    }

    @Override
    public int getCount() {
        return pages == null ? 0 : pages.size();
    }


    @Override
    public Object createPageInContainer(ComponentContainer componentContainer, int i) {
        componentContainer.addComponent(pages.get(i));
        return componentContainer;
    }

    @Override
    public void destroyPageFromContainer(ComponentContainer componentContainer, int i, Object o) {
        componentContainer.removeComponent(pages.get(i));
    }

    @Override
    public boolean isPageMatchToObject(Component component, Object o) {
        return component == o;
    }
    
}

②ViewCreaterHelper用于创建page页；

public final class ViewCreateHelper {

    private Context slice;
    private HashMap<String, ListAdapter> cache;

    public ViewCreateHelper(Context abilitySlice) {
        this.slice = abilitySlice;
        cache = new HashMap<>();
    }

    public Component createView(String title) {
        Component mainComponent =
                LayoutScatter.getInstance(slice).parse(ResourceTable.Layout_pager_item, null, false);
        if (!(mainComponent instanceof ComponentContainer)) {
            return null;
        }
        ComponentContainer rootLayout = (ComponentContainer) mainComponent;
        initView(mainComponent,title);
        return rootLayout;
    }

    public void initView(Component mainComponent,String title) {
        // 列表
        ListContainer  listContainer = (ListContainer) mainComponent.findComponentById(ResourceTable.Id_list_main);
        ListAdapter<NewsInfo> listAdapter = new ListAdapter<NewsInfo>(slice, ResourceTable.Layout_item_news_layout, getData(0, title)) {
            @Override
            public void convert(ViewHolder viewHolder, NewsInfo item, int position) {
                viewHolder.setText(ResourceTable.Id_item_news_title, item.getTitle());
                viewHolder.setText(ResourceTable.Id_item_news_desc, item.getDescription());

            }
        };
        listContainer.setItemProvider(listAdapter);
        listContainer.setItemClickedListener((list, component, i, l) -> {
//            Intent in = new Intent();
//            in.setElementName("", component.getContext().getBundleName(), DetailAbility.class.getName());
//            slice.startAbility(in, 0);
        });

        cache.put(title, listAdapter);
    }


    public List<NewsInfo> getData(int tab, String title) {
        List<NewsInfo> curData = new ArrayList<>();
        for (int i = 0; i < 20; i++) {
            NewsInfo info = new NewsInfo();
            info.setTitle("标题：" + title + i);
            info.setDescription("我是描述啦" + title + Math.random());
            curData.add(info);
        }
        return curData;
    }

}

③list适配器；

public abstract class ListAdapter<T> extends BaseItemProvider {

    private List<T> data;
    private Context ct;
    private int itemId;

    public ListAdapter(Context ct, int itemId, List<T> data) {
        this.data = data;
        this.ct = ct;
        this.itemId = itemId;
    }

    public abstract void convert(ViewHolder viewHolder, T item, int position);

    @Override
    public int getCount() {
        return data == null ? 0 : data.size();
    }

    @Override
    public T getItem(int i) {
        return data.get(i);
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    @Override
    public Component getComponent(int i, Component component, ComponentContainer componentContainer) {
        ViewHolder viewHolder = null;
        if (component == null) {
            Component itemView = LayoutScatter.getInstance(ct).parse(itemId, componentContainer, false);
            viewHolder = new ViewHolder(ct, itemView, componentContainer, i);
            viewHolder.layoutId = itemId;
        } else {
            Object object = component.getTag();
            if (object instanceof ViewHolder) {
                viewHolder = (ViewHolder) object;
                viewHolder.position = i;
            }
        }
        convert(viewHolder, getItem(i), i);
        return viewHolder == null ? null : viewHolder.getComponentView();
    }
}

④ViewHolder，可自行添加其他逻辑；

public class ViewHolder {
    int position;
    int layoutId;
    private Component component;
    private Context context;
    private HashMap<Integer, Component> views;

    ViewHolder(Context context, Component itemView, ComponentContainer parent, int position) {
        this.context = context;
        this.component = itemView;
        this.position = position;
        views = new HashMap<>(0);
        component.setTag(this);
    }

    @SuppressWarnings("unchecked")
    public <T extends Component> T getView(int viewId) {
        Component view = views.get(viewId);
        if (view == null) {
            view = component.findComponentById(viewId);
            views.put(viewId, view);
        }
        return (T) view;
    }

    Component getComponentView() {
        return component;
    }

    public void setText(int viewId, String text) {
        Text tv = getView(viewId);
        tv.setText(text);
    }

    public void setImageResource(int viewId, int resId) {
        Image image = getView(viewId);
        image.setPixelMap(resId);
        image.setScaleMode(Image.ScaleMode.STRETCH);
    }

}

End

其他资源文件未列举出，请参考完整demo。
github Demo源码

遗留问题思考

1、当点击tab切换时，若tab未完全显示，最好可以自动滑动展示完整tab；
2、未做下拉刷新与加载更多，涉及到滑动事件冲突；