Flutter-BottomNavigationBar切换页面 保存状态

效果图

Jul-22-2019 15-38-50.gif

1. 创建主页面

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State {
  int _currentIndex = 0;
  final List _pages = List();
  PageController _controller;

  @override
  void initState() {
    super.initState();
    _pages..add(MainPage())..add(MinePage());
    _controller = PageController(initialPage: 0);
  }

  @override
  void dispose() {
    super.dispose();
    _controller.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      bottomNavigationBar: _buildBottomNavigationBarWidget(),
      body: _buildBodyWidget(),
    );
  }

  Widget _buildBodyWidget() {
    return PageView.builder(
      controller: _controller,
      itemCount: _pages.length,
      physics: NeverScrollableScrollPhysics(),
      itemBuilder: (context, index) {
        return _pages[index];
      },
      onPageChanged: (index) {
        if (index != _controller) {
          setState(() {
            _currentIndex = index;
          });
        }
      },
    );
  }

  Widget _buildBottomNavigationBarWidget() {
    return BottomNavigationBar(
      type: BottomNavigationBarType.fixed,
      currentIndex: _currentIndex,
      fixedColor: Colors.amber,
      items: [
        BottomNavigationBarItem(title: Text("首页"), icon: Icon(Icons.home)),
        BottomNavigationBarItem(title: Text("我的"), icon: Icon(Icons.person))
      ],
      onTap: (index) {
        _controller.jumpToPage(index);
      },
    );
  }
}

2.创建2个子页面

class MainPage extends StatefulWidget {
  @override
  _MainPageState createState() => _MainPageState();
}

class _MainPageState extends State
    with AutomaticKeepAliveClientMixin {
  @protected
  bool get wantKeepAlive => true;
  int _count = 0;

  @override
  Widget build(BuildContext context) {
    super.build(context);
    return Scaffold(
      appBar: AppBar(
        title: Text("首页"),
      ),
      body: Center(
        child: Text("状态$_count"),
      ),
      floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {
            setState(() {
              _count++;
            });
          }),
    );
  }
}

class MinePage extends StatefulWidget {
  @override
  _MinePageState createState() => _MinePageState();
}

class _MinePageState extends State
    with AutomaticKeepAliveClientMixin {
  @protected
  bool get wantKeepAlive => true;
  int _count = 0;

  @override
  Widget build(BuildContext context) {
    super.build(context);
    return Scaffold(
      appBar: AppBar(
        title: Text("我的"),
      ),
      body: Center(
        child: Text("状态$_count"),
      ),
      floatingActionButton: FloatingActionButton(
          child: Icon(Icons.add),
          onPressed: () {
            setState(() {
              _count++;
            });
          }),
    );
  }
}