如何处理屏幕更改上的颤振WebviewScaffold？

Question

我有一个主屏幕，显示标题图像和按钮路由到第二个屏幕，和一个webview(脚手架)在它下面的容器。当我切换到第二个屏幕时，webview仍然存在。这似乎是一个类似于这个(Flutter: to close a webview when you left the page)的问题，但我不知道如何实现dispose事件。有人能帮忙吗？我正在使用flutter_webview_plugin包。这是我的代码：

import 'package:flutter/material.dart';

import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

import 'dart:async';

import './SecondScreen.dart';

String selectedUrl = 'https://flutter.io';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  final flutterWebViewPlugin = FlutterWebviewPlugin();

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Generated App',
      theme: new ThemeData(
        primarySwatch: Colors.purple,
        primaryColor: const Color(0xFF8e80a8),
        accentColor: const Color(0xFF8e80a8),
        canvasColor: const Color(0xFF8e80a8),
      ),
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {


  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(color: Color(0xFF8e80a8)),
      child: new Column(
          mainAxisAlignment: MainAxisAlignment.start,
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Padding(
              padding: const EdgeInsets.fromLTRB(10, 30, 10, 5),
              child: new Image.asset(
                'lib/assets/newoldralogo1.png',
              ),
            ),
            Container(
              constraints: BoxConstraints.expand(
                height:
                    Theme.of(context).textTheme.display1.fontSize * 1.1 + 10.0,
              ),
              child: new Stack(fit: StackFit.expand,
                  children: <Widget>[
                Container(
                  decoration: BoxDecoration(color: Color(0xFF8e80a8)),
                  child: Padding(
                    padding: const EdgeInsets.fromLTRB(10, 10, 10, 10),
                    child: Image.asset(
                      "lib/assets/newoldralogo1.png",
                      alignment: Alignment.topCenter,
                      fit: BoxFit.fitWidth,
                    ),
                  ),
                ),
                Container(
                  child: RaisedButton(
                    onPressed: () {
                      Navigator.push(
                        context,
                        MaterialPageRoute(builder: (context) => SecondScreen()),
                      );
                    },
                    color: Color(0xFFFFFF),
                  ),
                ),
              ]),
            ),

            Container(
              constraints: BoxConstraints.expand(
                height:
                    Theme.of(context).textTheme.display1.fontSize * 1.1 + 300.0,
              ),
              padding: const EdgeInsets.fromLTRB(10, 15, 10, 5),
              color: Color(0xFF8e80a8),
              alignment: Alignment.center,
              child: Container(
                child: WebviewScaffold(
                  url:
                      ('https://flutter.io/'),
                ),
              ),
            )
          ]),
    );
  }
}

/*
@override
void dispose() {
  super.dispose();
  _MyHomePageState();

}
*/

Answer 1

一个解决方案是将"Navigator.push“更改为”Navigator.pushRemove“。这将意味着第一个屏幕不会再次出现，所以按后退按钮(至少在Android设备上)就会退出应用程序。这不完全是我想要做的，但会暂时奏效的。

如果有人能告诉我把“处置”的东西放在哪里，我还是很想知道！在此期间，我会继续努力。感谢那些在网上分享了这么多有用信息的人！

顺便提一下，这是新代码，稍微清理了一下：

导入‘WebView /Material.DAT’；ImportScreen.DAT‘；类WebView扩展StatefulWidget {@重写_WebViewState createState() => _WebViewState()；}类_WebViewState扩展状态{ TextEditingController控制器=TextEditingController；FlutterWebviewPlugin flutterWebviewPlugin = FlutterWebviewPlugin()；var urlString = "https://stackoverflow.com/questions/43692923/flutter-container-onpressed"；launchUrl() { setState(() )；()；}；}@重载initState() { super.initState()；super.initState(){ print(wvs.type)；} //这部分没有工作@重写super.dispose(){ _WebViewState()；//关闭这里的super.dispose()；} @override (BuildContext上下文){返回容器(装饰:BoxDecoration(颜色:颜色(0xFF8e80a8)，子列( mainAxisAlignment: MainAxisAlignment.start，mainAxisSize: MainAxisSize.min，crossAxisAlignment: CrossAxisAlignment.center，子代:新GestureDetector( onTap：() ){ Navigator.pushReplacement(上下文)，MaterialPageRoute(构建器：(上下文) => SecondScreen() )；}，子:填充(填充: const EdgeInsets.fromLTRB(10，40，10，10)，子容器:新容器(约束: BoxConstraints.expand(高度:Theme.of(上下文).textTheme.display1.fontSize* 1.1 + 40.0，)，子:新Image.asset(‘lib/assets/newoldralogo1menuBuon3.png’，对齐: Alignment.topCenter，fit: BoxFit.fitWidth，)，)，填充(填充: const EdgeInsets.all(10.0)，容器(约束条件: BoxConstraints.expand(高度:Theme.of(上下文).textTheme.display1.fontSize* 1.1 + 250.0，)，子容器: WebviewScaffold( url: urlString，withZoom: false，)，)，) )；}}

Answer 2

当用户导航到第二个屏幕时隐藏web视图

flutterWebViewPlugin.hide();

并在用户返回时再次显示。

flutterWebViewPlugin.show();

应该解决这个问题。通过这种方式，用户可以在导航到第二屏幕后导航回第一屏幕。

记住等待Navigator.push()到第二个屏幕。

import 'package:flutter/material.dart';

import 'package:flutter_webview_plugin/flutter_webview_plugin.dart';

import 'dart:async';

import './SecondScreen.dart';

String selectedUrl = 'https://flutter.io';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  final flutterWebViewPlugin = FlutterWebviewPlugin();

  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Generated App',
      theme: new ThemeData(
        primarySwatch: Colors.purple,
        primaryColor: const Color(0xFF8e80a8),
        accentColor: const Color(0xFF8e80a8),
        canvasColor: const Color(0xFF8e80a8),
      ),
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key}) : super(key: key);

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

class _MyHomePageState extends State<MyHomePage> {


  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(color: Color(0xFF8e80a8)),
      child: new Column(
          mainAxisAlignment: MainAxisAlignment.start,
          mainAxisSize: MainAxisSize.min,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Padding(
              padding: const EdgeInsets.fromLTRB(10, 30, 10, 5),
              child: new Image.asset(
                'lib/assets/newoldralogo1.png',
              ),
            ),
            Container(
              constraints: BoxConstraints.expand(
                height:
                    Theme.of(context).textTheme.display1.fontSize * 1.1 + 10.0,
              ),
              child: new Stack(fit: StackFit.expand,
                  children: <Widget>[
                Container(
                  decoration: BoxDecoration(color: Color(0xFF8e80a8)),
                  child: Padding(
                    padding: const EdgeInsets.fromLTRB(10, 10, 10, 10),
                    child: Image.asset(
                      "lib/assets/newoldralogo1.png",
                      alignment: Alignment.topCenter,
                      fit: BoxFit.fitWidth,
                    ),
                  ),
                ),
                Container(
                  child: RaisedButton(
                    onPressed: () async {
                      flutterWebViewPlugin.hide();
                      await Navigator.push(
                        context,
                        MaterialPageRoute(builder: (context) => SecondScreen()),
                      );
                      flutterWebViewPlugin.show();
                    },
                    color: Color(0xFFFFFF),
                  ),
                ),
              ]),
            ),

            Container(
              constraints: BoxConstraints.expand(
                height:
                    Theme.of(context).textTheme.display1.fontSize * 1.1 + 300.0,
              ),
              padding: const EdgeInsets.fromLTRB(10, 15, 10, 5),
              color: Color(0xFF8e80a8),
              alignment: Alignment.center,
              child: Container(
                child: WebviewScaffold(
                  url:
                      ('https://flutter.io/'),
                ),
              ),
            )
          ]),
    );
  }
}