如何在flutter webview中启用文本选择模式(复制/粘贴/选择)？

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

class WebViewPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('WebView'),
      ),
      body: WebView(
        initialUrl: 'https://example.com',
      ),
    );
  }
}

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

class WebViewPage extends StatelessWidget {
  final Set<JavascriptChannel> javascriptChannels = [
    JavascriptChannel(
      name: 'TextSelection',
      onMessageReceived: (JavascriptMessage message) {
        // 处理来自WebView的消息
        // 在这里可以执行复制、粘贴、选择等操作
      },
    ),
  ].toSet();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('WebView'),
      ),
      body: WebView(
        initialUrl: 'https://example.com',
        javascriptMode: JavascriptMode.unrestricted,
        javascriptChannels: javascriptChannels,
        onPageFinished: (String url) {
          // WebView加载完成后执行JavaScript代码
          // 启用文本选择模式
          webView.evaluateJavascript('''
            document.body.style.webkitUserSelect='text';
            document.body.style.webkitTouchCallout='default';
          ''');
        },
      ),
    );
  }
}