20、Scaffold属性 BottomNavigationBar 自定义底部导航

class MyFlutter1 extends StatefulWidget {
  const MyFlutter1({super.key});

  @override
  State<MyFlutter1> createState() => _MyFlutter1State();
}

class _MyFlutter1State extends State<MyFlutter1> {
  int _currentIndex =0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text("这是导航栏")),
      bottomNavigationBar: BottomNavigationBar(
       currentIndex: _currentIndex,  //默认选中第几个
       iconSize: 35,
       type:BottomNavigationBarType.fixed, //如果底部有4个或者4个以上的进行选择

       fixedColor: const Color.fromARGB(255, 54, 244, 171), //选中的颜色
       onTap: (index){   //选中变化回调函数
         print("监听$index");
         setState(() {
            _currentIndex = index;
         });
       },
       items: const [
        BottomNavigationBarItem(icon: Icon(Icons.home), label: "首页"),
        BottomNavigationBarItem(icon: Icon(Icons.timeline), label: "时间"),
        BottomNavigationBarItem(icon: Icon(Icons.my_library_add), label: "我的"),
      ]),
      body: const Center(
          child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [],
      )),
    );
  }
}