5

I want webview not reload when I switch appbar in my flutter app, but I don't know how should I do, and I am sorry that I am a beginner.

This is my recorded gif:

I searched on Google, but I didn't find an answer related to this.

//index.dart
import 'package:flutter/material.dart';
import 'navigation_tab.dart';
import '../home/home_page.dart';
import '../market/market_page.dart';
import '../my/my_page.dart';

class Index extends StatefulWidget {

  @override
  _IndexState createState() => new _IndexState();

}


class _IndexState extends State<Index> with TickerProviderStateMixin {

  int _currentIndex = 0;
  List<NavigationTab> _navigationTabs;
  List<StatefulWidget> _pageList;
  StatefulWidget _currentPage;

  @override
  void initState() {
    super.initState();
    _navigationTabs = <NavigationTab>[
      new NavigationTab(icon: new Icon(Icons.account_balance), title: new Text("home"), vsync: this),
      new NavigationTab(icon: new Icon(Icons.local_mall), title: new Text("market"), vsync: this),
      new NavigationTab(icon: new Icon(Icons.account_box), title: new Text("my"), vsync: this),
    ];

    _pageList = <StatefulWidget>[
      new HomePage(),
      new MarketPage(),
      new MyPage(),
    ];
    _currentPage = _pageList[_currentIndex];
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: _currentPage,
      bottomNavigationBar: new BottomNavigationBar(
        items: _navigationTabs.map((tab) => tab.item).toList(),
        currentIndex: _currentIndex,
        fixedColor: Colors.blue,
        type: BottomNavigationBarType.fixed,
        onTap: (int index) {
          setState(() {
            _currentIndex = index;
            _currentPage = _pageList[index];
          });
        },
      ),
    );
  }

}

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

class HomePage extends StatefulWidget {

  @override
  _HomePageState createState() => new _HomePageState();

}

class _HomePageState extends State<HomePage> {


  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: PreferredSize(
          child: new AppBar(
            title: new Text("home"),
            centerTitle: true,
          ), 
          preferredSize: Size.fromHeight(40)
      ),
      body: new Center(
        child: new Text("this is home page", style: TextStyle(fontSize: 36)),
      ),
    );
  }

}
//market_page.dart
import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

class MarketPage extends StatefulWidget {

  @override
  _MarketPageState createState() => new _MarketPageState();

}

class _MarketPageState extends State<MarketPage> {


  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: PreferredSize(
          child: new AppBar(
            title: new Text("market"),
            centerTitle: true,
          ),
          preferredSize: Size.fromHeight(40)
      ),
      body: new WebviewScaffold(
          url: "https://flutter.dev/",
          withLocalStorage: true,
          withJavascript: true
      ),
    );
  }

}

I want webview page keepalive, like vue, How should I do it?

1

1 Answer 1

6

Basically, your MarketPage widget is re-building whenever you open it. You can use keep alive to attain your required behaviour.

//market_page.dart
import 'package:flutter/material.dart';
import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

class MarketPage extends StatefulWidget {

  @override
  _MarketPageState createState() => new _MarketPageState();

}

class _MarketPageState extends State<MarketPage> with AutomaticKeepAliveClientMixin{


  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: PreferredSize(
          child: new AppBar(
            title: new Text("market"),
            centerTitle: true,
          ),
          preferredSize: Size.fromHeight(40)
      ),
      body: new WebviewScaffold(
          url: "https://flutter.dev/",
          withLocalStorage: true,
          withJavascript: true
      ),
    );
  }

 @override
 bool get wantKeepAlive => true;

}

Update - Here is an example of how you can do it using AutomaticKeepAliveClientMixin. This is working fine for me. I'm using Pageview and webview_flutter instead of flutter_webview_plugin.

main.dart

import 'package:flutter/material.dart';
import 'package:webview_project/pag1.dart';
import 'package:webview_project/page2.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _currentIndex = 0;
  var controller = PageController();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: PageView(
        physics: NeverScrollableScrollPhysics(),
        controller: controller,
        children: <Widget>[
          Page1(),
          Page2(),
        ],
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), title: Text('Home')),
          BottomNavigationBarItem(icon: Icon(Icons.web), title: Text('Web')),
        ],
        currentIndex: _currentIndex,
        onTap: (index) {
          setState(() {
            _currentIndex = index;
            controller.jumpToPage(index);
          });
        },
      ),
    );
  }
}

page1.dart

import 'package:flutter/material.dart';

class Page1 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Text('Page1'),
    );
  }
}

page2.dart

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

class Page2 extends StatefulWidget {
  @override
  _Page2State createState() => _Page2State();
}

class _Page2State extends State<Page2>
    with AutomaticKeepAliveClientMixin<Page2> {
  @override
  Widget build(BuildContext context) {
    return WebView(
      initialUrl: 'https://www.flutter.dev/',
    );
  }

  @override
  bool get wantKeepAlive => true;
}

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5 Comments

First of all, thank you for your answer. then I added the code the way you want it, but the page will still reload, I want the status and scrollbar position of the second page to be the same as before the switch
I should add, the reload I am discussing here refers to the re-rendering of ui.
I have updated the answer. Please check it. Let me know if this works for you.
thanks for your answer, but is not working for my flutter application.
but your answer gives me ideas, I found information about AutomaticKeepAliveClientMixin. this answer helped me: stackoverflow.com/a/54999503/11768649

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