Flutter底部导航栏

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

import 'home_page.dart';
import 'product_page.dart';
import 'market_page.dart';
import 'member_page.dart';

class IndexPage extends StatefulWidget {
  @override
  _IndexPageState createState() => _IndexPageState();
}

class _IndexPageState extends State {
  final List bottomTabs = [
    BottomNavigationBarItem(
      icon: Icon(Icons.home),
      title: Text('首页'),
    ),
    BottomNavigationBarItem(
      icon: Icon(Icons.store),
      title: Text('市场')
    ),
    BottomNavigationBarItem(
        icon: Icon(CupertinoIcons.tag),
        title: Text('产品')
    ),
    BottomNavigationBarItem(
      icon: Icon(Icons.person),
      title: Text('中心'),
    )
  ];

  final List tabBodies = [
    HomePage(),
    MarketPage(),
    ProductPage(),
    MemberPage(),
  ];

  int currentIndex = 0;
  var currentPage;
  @override
  void initState() {
    currentPage = tabBodies[currentIndex];
    super.initState();
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Color.fromRGBO(244, 245, 245, 1.0),
      bottomNavigationBar: new Container(
        child: BottomNavigationBar(
          items: bottomTabs,
          type: BottomNavigationBarType.fixed,
          currentIndex: currentIndex,
          selectedFontSize: 14,
          unselectedFontSize: 12,
          iconSize: 20,
          selectedItemColor: Colors.blue,
          unselectedItemColor: Colors.black54,
          onTap: (index){
            setState(() {
              currentIndex = index;
              currentPage = tabBodies[currentIndex];
            });
          },
        ),
      ),
      body: currentPage
    );
  }
}