flutter 不规则底部工具栏实现

import 'package:flutter/material.dart';
import 'each_view.dart';

class BottomAppBarDemo extends StatefulWidget {
  _BottomAppBarDemoState createState() => _BottomAppBarDemoState();
}

class _BottomAppBarDemoState extends State<BottomAppBarDemo> {
  List<Widget> _eachView; //创建视图数组
  int _index = 0; //数组索引，通过改变索引值改变视图

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
    _eachView = List();
    _eachView
      ..add(EachView('Home'))
      ..add(EachView('Home1'))
      ..add(EachView('Home2'))
      ..add(EachView('Home3'))
      ..add(EachView('Home4'));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: _eachView[_index],
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.of(context)
              .push(MaterialPageRoute(builder: (BuildContext context) {
            return EachView('New Page');
          }));
        },
        tooltip: 'Increment',
        child: Icon(
          Icons.add,
          color: Colors.white,
        ),
        backgroundColor: Colors.green,
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
      bottomNavigationBar: BottomAppBar(
        color: Colors.white,
        shape: CircularNotchedRectangle(),
        child: Row(
          mainAxisSize: MainAxisSize.max,
          mainAxisAlignment: MainAxisAlignment.spaceAround,
          children: <Widget>[

            IconButton(
                icon: Icon(Icons.accessible_forward),
//                color: Colors.white,
                onPressed: () {
                  setState(() {
                    _index = 0;
                  });
                }),

                IconButton(
                    icon: Icon(Icons.access_alarm),
//                color:Colors.white,
                    onPressed: () {
                      setState(() {
                        _index = 1;
                      });
                    }),
            IconButton(
                icon: Icon(Icons.accessible_forward),
                color: Colors.transparent,
                onPressed: () {
                  setState(() {
                    _index = 2;
                  });
                }),
            IconButton(
                icon: Icon(Icons.account_balance_wallet),

//                color:Colors.white,
                onPressed: () {
                  setState(() {
                    _index = 3;
                  });
                }),
            IconButton(
                icon: Icon(Icons.airport_shuttle),
//                color:Colors.white,
                onPressed: () {
                  setState(() {
                    _index = 4;
                  });
                }),
          ],
        ),
      ),
    );
  }
}

import 'package:flutter/material.dart';

class EachView extends StatefulWidget {
  String _title;
  EachView(this._title);
  @override
  _EachViewState createState() => _EachViewState();
}

class _EachViewState extends State<EachView> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar:AppBar(title:Text(widget._title)),
      body: Center(child:Text(widget._title)),
    );
  }
}

效果：