Flutter -如何用前置摄像头扫描二维码？

dependencies:
  qr_code_scanner: ^0.4.0

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

class QRScanPage extends StatefulWidget {
  @override
  _QRScanPageState createState() => _QRScanPageState();
}

class _QRScanPageState extends State<QRScanPage> {
  final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
  QRViewController? controller;
  bool scanStarted = false;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('QR Scanner'),
      ),
      body: Column(
        children: [
          Expanded(
            flex: 5,
            child: QRView(
              key: qrKey,
              onQRViewCreated: _onQRViewCreated,
            ),
          ),
          Expanded(
            flex: 1,
            child: Center(
              child: ElevatedButton(
                onPressed: () {
                  setState(() {
                    scanStarted = !scanStarted;
                  });
                },
                child: Text(scanStarted ? 'Stop Scan' : 'Start Scan'),
              ),
            ),
          ),
        ],
      ),
    );
  }

  void _onQRViewCreated(QRViewController controller) {
    this.controller = controller;
    controller.scannedDataStream.listen((scanData) {
      // 处理扫描到的二维码数据
      print(scanData.code);
    });
  }

  @override
  void dispose() {
    controller?.dispose();
    super.dispose();
  }
}

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'QR Scanner',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Center(
        child: ElevatedButton(
          onPressed: () {
            Navigator.push(
              context,
              MaterialPageRoute(builder: (context) => QRScanPage()),
            );
          },
          child: Text('Scan QR Code'),
        ),
      ),
    );
  }
}