flutter tabbar 切换到某一个index 的时候，把

flutter tabbar 切换到某一个index 的时候，把index 重置到指定的位置，

举例 切换到1 重置到 0
代码如下
如果不需要动画 可以用 jumpToPage

   TabController _tabController;
   PageController _pageController;

  @override
  void initState() {
    super.initState();
    _tabController = TabController(length: 2, vsync: this);
    _pageController = PageController(initialPage: 1);
  }

  @override
  void dispose() {
    _tabController.dispose();
    _pageController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('My Tab Bar'),
        bottom: TabBar(
          controller: _tabController,
          onTap: (index) {
            if(index==1){
              // index = 0;
              _tabController.index = 0;
              _pageController.animateToPage(
                0,
                duration: Duration(milliseconds: 30),
                curve: Curves.easeInOut,
              );
              return;
            }
            _pageController.animateToPage(
              index,
              duration: Duration(milliseconds: 300),
              curve: Curves.easeInOut,
            );
          },
          tabs: [
            Tab(
              text: 'Tab 1',
            ),
            Tab(
              text: 'Tab 2',
            ),
          ],
        ),
      ),
      body: PageView(
        controller: _pageController,
        onPageChanged: (index) {
          print('当前页面: $index');
          if(index==1){
            // index = 0;
            _tabController.index = 0;
            _pageController.animateToPage(
              0,
              duration: Duration(milliseconds: 30),
              curve: Curves.easeInOut,
            );
            return;

          }
          _tabController.animateTo(index);
          _pageController.animateToPage(
            index,
            duration: Duration(milliseconds: 300),
            curve: Curves.easeInOut,
          );
        },
        children: [
          // 第一个页面的内容
          // ...
          Center(child: Text("1"),),
          Center(child: Text("2"),)
        ],
      ),
      bottomNavigationBar: TabBar(
        controller: _tabController,
        onTap: (index) {
          _pageController.animateToPage(
            index,
            duration: Duration(milliseconds: 300),
            curve: Curves.easeInOut,
          );
        },
        tabs: [
          Tab(
            text: 'Tab 1',
          ),
          Tab(
            text: 'Tab 2',
          ),
        ],
      ),
    );