플러터로 웹뷰 세팅하기

Flutter 앱에 WebView 추가 를 읽으면서 정리한 글입니다.

pubspec.yaml에 의존성 추가

아래 명령어로 플러그인을 추가합니다.

flutter pub add webview_flutter
flutter pub get

main.dart 에 웹뷰 추가

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
void main() {
  runApp(
    const MaterialApp(
      home: WebViewApp(),
    ),
  );
}
 
class WebViewApp extends StatefulWidget {
  const WebViewApp({Key? key}) : super(key: key);
 
  @override
  State<WebViewApp> createState() => _WebViewAppState();
}
 
class _WebViewAppState extends State<WebViewApp> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter WebView'),
      ),
      body: const WebView(
        initialUrl: 'https://flutter.dev',
      ),
    );
  }
}

하이브리드 컴포지션 설정

import 'dart:io';                            // Add this import.
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
void main() {
  runApp(
    const MaterialApp(
      home: WebViewApp(),
    ),
  );
}
 
class WebViewApp extends StatefulWidget {
  const WebViewApp({Key? key}) : super(key: key);
 
  @override
  State<WebViewApp> createState() => _WebViewAppState();
}
 
class _WebViewAppState extends State<WebViewApp> {
  // Add from here ...
  @override
  void initState() {
    if (Platform.isAndroid) {
      WebView.platform = SurfaceAndroidWebView();
    }
    super.initState();
  }
  // ... to here.
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter WebView'),
      ),
      body: const WebView(
        initialUrl: 'https://flutter.dev',
      ),
    );
  }
}

하이브리드 컴포지션이란 네이티브 웹뷰를 플러터 위젯 안에서 보여주는 것을 의미합니다.

페이지 로드 이벤트 수신 대기

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
class WebViewStack extends StatefulWidget {
  const WebViewStack({Key? key}) : super(key: key);
 
  @override
  State<WebViewStack> createState() => _WebViewStackState();
}
 
class _WebViewStackState extends State<WebViewStack> {
  var loadingPercentage = 0;
 
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        WebView(
          initialUrl: 'https://flutter.dev',
          onPageStarted: (url) {
            setState(() {
              loadingPercentage = 0;
            });
          },
          onProgress: (progress) {
            setState(() {
              loadingPercentage = progress;
            });
          },
          onPageFinished: (url) {
            setState(() {
              loadingPercentage = 100;
            });
          },
        ),
        if (loadingPercentage < 100)
          LinearProgressIndicator(
            value: loadingPercentage / 100.0,
          ),
      ],
    );
  }
}

위 코드처럼 웹뷰를 웹뷰스택이라는 Stateful 컴포넌트로 감싸줄 수 있습니다. 그리고 웹뷰스택의 로딩 상태값을 웹뷰의 로딩이벤트에서 조작하는 방식으로 설정하면 웹뷰 가 로드되는 동안 linearProgressIndicator가 움직이는 것을 보여줄 수 있습니다.

WebViewController를 사용하여 작업하기

WebViewStack을 아래와 같이 업데이트합니다.

import 'dart:async';     // Add this import for Completer
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
class WebViewStack extends StatefulWidget {
  const WebViewStack({required this.controller, Key? key}) : super(key: key); // Modify
 
  final Completer<WebViewController> controller;   // Add this attribute
 
  @override
  State<WebViewStack> createState() => _WebViewStackState();
}
 
class _WebViewStackState extends State<WebViewStack> {
  var loadingPercentage = 0;
 
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        WebView(
          initialUrl: 'https://flutter.dev',
          // Add from here ...
          onWebViewCreated: (webViewController) {
            widget.controller.complete(webViewController);
          },
          // ... to here.
          onPageStarted: (url) {
            setState(() {
              loadingPercentage = 0;
            });
          },
          onProgress: (progress) {
            setState(() {
              loadingPercentage = progress;
            });
          },
          onPageFinished: (url) {
            setState(() {
              loadingPercentage = 100;
            });
          },
        ),
        if (loadingPercentage < 100)
          LinearProgressIndicator(
            value: loadingPercentage / 100.0,
          ),
      ],
    );
  }
}

컨트롤러를 추가합니다. 컨트롤러는 Completer로, 콜백을 Future(Promise) 로 만듭니다.

탐색 컨트롤 만들기

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
class NavigationControls extends StatelessWidget {
  const NavigationControls({required this.controller, Key? key})
      : super(key: key);
 
  final Completer<WebViewController> controller;
 
  @override
  Widget build(BuildContext context) {
    return FutureBuilder<WebViewController>(
      future: controller.future,
      builder: (context, snapshot) {
        final WebViewController? controller = snapshot.data;
        if (snapshot.connectionState != ConnectionState.done ||
            controller == null) {
          return Row(
            children: const <Widget>[
              Icon(Icons.arrow_back_ios),
              Icon(Icons.arrow_forward_ios),
              Icon(Icons.replay),
            ],
          );
        }
 
        return Row(
          children: <Widget>[
            IconButton(
              icon: const Icon(Icons.arrow_back_ios),
              onPressed: () async {
                if (await controller.canGoBack()) {
                  await controller.goBack();
                } else {
                  ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('No back history item')),
                  );
                  return;
                }
              },
            ),
            IconButton(
              icon: const Icon(Icons.arrow_forward_ios),
              onPressed: () async {
                if (await controller.canGoForward()) {
                  await controller.goForward();
                } else {
                  ScaffoldMessenger.of(context).showSnackBar(
                    const SnackBar(content: Text('No forward history item')),
                  );
                  return;
                }
              },
            ),
            IconButton(
              icon: const Icon(Icons.replay),
              onPressed: () {
                controller.reload();
              },
            ),
          ],
        );
      },
    );
  }
}

위 코드로 네비게이션 바를 만들 수 있습니다. 컨트롤러를 상속받아서 뒤로/앞으로/새로고침 등을 수행합니다.

import 'dart:async';                                    // Add this import
 
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';  // Add this import back
 
import 'src/navigation_controls.dart';                  // Add this import
import 'src/web_view_stack.dart';
 
void main() {
  runApp(
    const MaterialApp(
      home: WebViewApp(),
    ),
  );
}
 
class WebViewApp extends StatefulWidget {
  const WebViewApp({Key? key}) : super(key: key);
 
  @override
  State<WebViewApp> createState() => _WebViewAppState();
}
 
class _WebViewAppState extends State<WebViewApp> {
  final controller = Completer<WebViewController>();    // Instantiate the controller
 
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter WebView'),
        // Add from here ...
        actions: [
          NavigationControls(controller: controller),
        ],
        // ... to here. 
      ),
      body: WebViewStack(controller: controller),       // Add the controller argument
    );
  }
}

위 코드처럼 메인에서 컨트롤러를 만들고 아래로 전달해줄 수 있습니다.

NavigationDelegate로 탐색 추적

import 'dart:async';
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
 
class WebViewStack extends StatefulWidget {
  const WebViewStack({required this.controller, Key? key}) : super(key: key);
 
  final Completer<WebViewController> controller;
 
  @override
  State<WebViewStack> createState() => _WebViewStackState();
}
 
class _WebViewStackState extends State<WebViewStack> {
  var loadingPercentage = 0;
 
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: [
        WebView(
          initialUrl: 'https://flutter.dev',
          onWebViewCreated: (webViewController) {
            widget.controller.complete(webViewController);
          },
          onPageStarted: (url) {
            setState(() {
              loadingPercentage = 0;
            });
          },
          onProgress: (progress) {
            setState(() {
              loadingPercentage = progress;
            });
          },
          onPageFinished: (url) {
            setState(() {
              loadingPercentage = 100;
            });
          },
          // Add from here ...
          navigationDelegate: (navigation) {
            final host = Uri.parse(navigation.url).host;
            if (host.contains('youtube.com')) {
              ScaffoldMessenger.of(context).showSnackBar(
                SnackBar(
                  content: Text(
                    'Blocking navigation to $host',
                  ),
                ),
              );
              return NavigationDecision.prevent;
            }
            return NavigationDecision.navigate;
          },
          // ... to here.
        ),
        if (loadingPercentage < 100)
          LinearProgressIndicator(
            value: loadingPercentage / 100.0,
          ),
      ],
    );
  }
}

NavigationDelegate를 이용하여 탐색을 추적하고 차단할 수 있습니다.