flutter 之BottomNavigationBar属性

参考：jianshu.com/p/22d8974c5e04

 return Scaffold(
      backgroundColor: Color(0xfff6f6f6),
      bottomNavigationBar: BottomNavigationBar(
        type: BottomNavigationBarType.fixed,
        onTap: _onTap,

        selectedItemColor: Theme.of(context).primaryColor, // 选中的item颜色
        unselectedItemColor: Color(0xff666666),　　　　　　　　// 未选中的item颜色
        selectedIconTheme: IconThemeData(color: Colors.blue, size: AppConfig.screenUtil(val: 50, val2: 20)), // 选中的icon样式
        unselectedIconTheme: IconThemeData(color: Colors.black, size: AppConfig.screenUtil(val: 50, val2: 20)), // 未选择的icon样式
        selectedFontSize: AppConfig.screenUtil(val: 25, val2: 20), // 选择的item文字大小
        unselectedFontSize: AppConfig.screenUtil(val: 25, val2: 20), // 未选择的item文字大小
        currentIndex: _currentIndex,


        //被选择item的颜色
        items: <BottomNavigationBarItem>[
          BottomNavigationBarItem(title: Text('首页', ),  icon: Icon( Icons.home,)),
          BottomNavigationBarItem(title: Text('全部产品', ), icon: Icon( IconData(0xe7f9, fontFamily: 'iconfont'),)),
          BottomNavigationBarItem(
              title: Text('产品分类'),  icon: Icon( IconData(0xe7f9, fontFamily: 'iconfont'),)),
        ],
      ),