anchor.diff:  
     @override
     Widget build(BuildContext context) {
  -    if (widget.type == GSYTabBarWidget.TOP_TAB) {
  +    if (this._type == GSYTabBarWidget.TOP_TAB) {
         ///顶部tab bar
         return new Scaffold(
  -        floatingActionButton: widget.floatingActionButton,
  -        persistentFooterButtons: widget.tarWidgetControl == null ? [] : widget.tarWidgetControl.footerButton,
  +        floatingActionButton: _floatingActionButton,
  +        persistentFooterButtons: _tarWidgetControl == null ? [] : _tarWidgetControl.footerButton,
           appBar: new AppBar(
             backgroundColor: Theme.of(context).primaryColor,
  -          title: widget.title,
  +          title: _title,
             bottom: new TabBar(
               controller: _tabController,
               tabs: widget.tabItems,
  -            indicatorColor: widget.indicatorColor,
  +            indicatorColor: _indicatorColor,
             ),
           ),
           body: new PageView(
  -          controller: widget.topPageControl,
  -          children: widget.tabViews,
  +          controller: _pageController,
  +          children: _tabViews,
             onPageChanged: (index) {
               _tabController.animateTo(index);
  -            widget.onPageChanged?.call(index);
  +            _onPageChanged?.call(index);
             },
           ),
         );
  
positive.code:             //TabBar导航标签，底部导航放到Scaffold的bottomNavigationBar中
              controller: _tabController, //配置控制器
              tabs: widget.tabItems,
              indicatorColor: widget.indicatorColor, //tab标签的下划线颜色
            ),
          ));
    }
  
negative.code:   }) : super(key: key);
  
    @override
    _GSYTabBarState createState() => new _GSYTabBarState(
      type,
      tabViews,
      indicatorColor,
      title,
      drawer,
      floatingActionButton,
      tarWidgetControl,
      topPageControl,
      onPageChanged,
    );
  }
  
  // ignore: mixin_inherits_from_not_object
  class _GSYTabBarState extends State<GSYTabBarWidget> with SingleTickerProviderStateMixin {
    final int _type;
  
    final List<Widget> _tabViews;
  
    final Color _indicatorColor;
  
    final Widget _title;
  
    final Widget _drawer;
  
    final Widget _floatingActionButton;
  
    final TarWidgetControl _tarWidgetControl;
  
    final PageController _pageController;
  
    final ValueChanged<int> _onPageChanged;
  
    _GSYTabBarState(
        this._type,
        this._tabViews,
        this._indicatorColor,
        this._title,
        this._drawer,
        this._floatingActionButton,
        this._tarWidgetControl,
        this._pageController,
        this._onPageChanged,
        ) : super();
  
    TabController _tabController;
  
  