投稿者: route83

import 'package:flutter/material.dart';
import 'package:url_launcher/url_launcher_string.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

void _openUrl() async {
  const url = 'https://messageexchanger-fa3e1.web.app';
  if (await canLaunchUrlString(url)) {
    await launchUrlString(url);
  } else {
    throw 'can not access this url.';
  }
}

class _MyHomePageState extends State<MyHomePage> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        width: double.infinity,
        height: double.infinity,
        alignment: Alignment.center,
        child: Column(
          children: <Widget>[
            Expanded(
              flex: 1,
              child: Container(
                alignment: Alignment.center,
                child:Image.asset('images/sample.jpg'),),),
            Expanded(
              flex :1,
              child: Container(
                alignment: Alignment.center,
                child: ElevatedButton(
                  onPressed: () async {
                    _openUrl();
                  },
                  style: ElevatedButton.styleFrom(
                    shape: RoundedRectangleBorder(
                      borderRadius: BorderRadius.circular(5),
                    ),
                  ),
                  child: const Text('Web'),
                  ),))
          ],
        ),
      ),
    );
  } 
}

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.sample">

    <queries>
        <intent>
            <action android:name="android.intent.action.VIEW" />
            <data android:scheme="https" />
        </intent>
    </queries>

   <application
        android:label="sample"
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher">

　　・・・

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

class SubPage extends StatelessWidget  {
  const SubPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body:WebViewWidget(
            controller: WebViewController()
              ..setJavaScriptMode(JavaScriptMode.unrestricted)
              ..loadRequest(Uri.parse("https://messageexchanger-fa3e1.web.app"))
          ),
    );
  }
}