我正在把 url_launcher 集成到我基于Flutter的支付SDK中：

import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:webview_flutter/webview_flutter.dart';
import 'package:url_launcher/url_launcher.dart';

class _PGPaymentModalState extends State<ArtoPaymentModal> {
  late final WebViewController _controller;
  bool _isLoading = true;

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

    _controller = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setBackgroundColor(Colors.white)
      ..addJavaScriptChannel(
        'PGSdkChannel',
        onMessageReceived: (JavaScriptMessage message) {
          _handleMessage(message.message);
        },
      )
      ..setNavigationDelegate(
        NavigationDelegate(
          onNavigationRequest: (NavigationRequest request) async {
            final theUrl = request.url;
            if (await canLaunchUrl(uri)) {
              await launchUrl(uri, mode: LaunchMode.externalApplication);
            } else {
              debugPrint('Cannot open URL: $url');
            }
            return NavigationDecision.prevent; // Cegah WebView load
          },
        ),
      )
      ..loadRequest(Uri.parse(url));
  }

VSCode提供了这个错误：

Target of URI doesn't exist: 'package:url_launcher/url_launcher.dart'.
Try creating the file referenced by the URI, or try using a URI for a file that does exist.darturi_does_not_exist

我已经在pubspec.yaml中添加了url_launcher，并重新运行 flutter pub get：

dependencies:
  flutter:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^1.0.8
  webview_flutter: ^4.13.1
  url_launcher: ^6.3.2

删除 pubspec.lock 和 .dart_tool 目录后再运行 flutter pub get 仍然无法解决问题。该如何修复？我正在使用Flutter 3.41.9

解决方案

在上面的代码中你使用了：

final theUrl = request.url;
if (await canLaunchUrl(uri)) {
  await launchUrl(uri, mode: LaunchMode.externalApplication);
} else {
  debugPrint('Cannot open URL: $url');
}

但变量 "uri" 不存在。应该改为：

final theUrl = request.url;
final uri = Uri.parse(theUrl) // This might change depending upon the type of response
if (await canLaunchUrl(uri)) {
  await launchUrl(uri, mode: LaunchMode.externalApplication);
} else {
  debugPrint('Cannot open URL: $url');
}

此外你还应该运行以下这些命令：

flutter pub add url_launcher
flutter clean
flutter pub get