flutter webview url重定向时无法返回

Question

我正在构建一个颤振应用程序。该应用程序的用途是在 webview 中显示网页。在此应用程序中有一个按钮。单击按钮时，需要打开 webview 并加载 url。 但有些网址有重定向。所以在应用中我们不能回头。例如一个网址。 http://sample.com/firstpage.html。在普通浏览器中输入网址时。它将自动重定向到 http://sample.com/secondpage.html 。在浏览器中，当单击 secondarypage.html 中的后退按钮时。它不会返回到firstpage.html。但在我的网络视图中它正在循环。 当我在网页视图中加载 http://sample.com/firstpage.html 时。首先它会加载firstpage.html，然后它会自动重定向到secondpage.html。之后当我点击后退按钮时。它再次加载firstpagehtml并再次自动加载secondpage.html。 如何在不进入firstpage.html的情况下返回。它在普通浏览器中工作正常，但在网络视图中不起作用。怎么解决？

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


        void main() => runApp(const MaterialApp(home: WebViewExample()));

        class WebViewExample extends StatefulWidget {
          const WebViewExample({super.key});

          @override
          State<WebViewExample> createState() => _WebViewExampleState();
        }

        class _WebViewExampleState extends State<WebViewExample> {
          @override
          Widget build(BuildContext context) {
            return Scaffold(
              backgroundColor: Colors.green,

              body: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: [
                  ElevatedButton(onPressed: (){
                    Navigator.push(context, MaterialPageRoute(builder: (context){ return WebViewExample1();}));
                  }, child: Text("open web view"))
                ],
              ),
            );
          }
        }


        class WebViewExample1 extends StatefulWidget {
          const WebViewExample1({super.key});

          @override
          State<WebViewExample1> createState() => _WebViewExample1State();
        }

        class _WebViewExample1State extends State<WebViewExample1> {
          late final WebViewController _controller;

          @override
          void initState() {
            super.initState();


          _loadPageFn2();
          }

          void _loadPageFn2(){
            final WebViewController controller =WebViewController();

            controller
              ..setJavaScriptMode(JavaScriptMode.unrestricted)
              ..setNavigationDelegate(
                NavigationDelegate(
                  onProgress: (int progress) {
                    debugPrint('WebView is loading (progress : $progress%)');
                  },
                  onPageStarted: (String url) {
                    debugPrint('Page started loading: $url');
                  },
                  onPageFinished: (String url) {
                    debugPrint('Page finished loading: $url');
                  },
                  onNavigationRequest: (NavigationRequest request) {
                    if (request.url.startsWith('https://www.youtube.com/')) {
                      debugPrint('blocking navigation to ${request.url}');
                      return NavigationDecision.prevent;
                    }
                    debugPrint('allowing navigation to ${request.url}');
                    return NavigationDecision.navigate;
                  },
                  onUrlChange: (UrlChange change) {
                    debugPrint('url change to ${change.url}');
                  },
                ),
              )

              ..setNavigationDelegate(
                NavigationDelegate(
                  onProgress: (int progress) {
                    debugPrint('WebView is loading (progress : $progress%)');
                  },
                  onPageStarted: (String url) {
                    debugPrint('Page started loading: $url');
                  },
                  onPageFinished: (String url) {
                    debugPrint('Page finished loading: $url');
                  },
                  onWebResourceError: (WebResourceError error) {
                    debugPrint('''
        Page resource error:
          code: ${error.errorCode}
          description: ${error.description}
          errorType: ${error.errorType}
          isForMainFrame: ${error.isForMainFrame}
                  ''');
                  },
                  onNavigationRequest: (NavigationRequest request)async {

                     debugPrint('allowing navigation to ${request.url}');
                     return NavigationDecision.navigate;

                  },
                  onUrlChange: (UrlChange change) {
                    debugPrint('url change to ${change.url}');
                  },
                ),
              )

              ..loadRequest(Uri.parse('http://sample.com/firstpage.html'));

            _controller = controller;

          }



          @override
          Widget build(BuildContext context) {
            return Scaffold(
              backgroundColor: Colors.green,

              body: WillPopScope(
                onWillPop: ()async{
                  
        if(await _controller.canGoBack()){
            _controller.goBack();
            return false;
          } else{
            return true;
          }

                },
                child: WebViewWidget(controller: _controller),
              ),
            );
          }

        }

Answer 1

这不是一个令人满意的答案：如果您根本不实现 onNavigationRequest 回调，则返回行为应该如您所期望的那样。

我认为这是 webview 库中的一个错误。