如何在Flutter WebView中将数据发布到URL

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

class MyWebView extends StatefulWidget {
  @override
  _MyWebViewState createState() => _MyWebViewState();
}

class _MyWebViewState extends State<MyWebView> {
  WebViewController _webViewController;
  TextEditingController _textEditingController;

  @override
  void initState() {
    super.initState();
    _textEditingController = TextEditingController();
  }

  @override
  void dispose() {
    _textEditingController.dispose();
    super.dispose();
  }

  void _publishDataToUrl() async {
    String data = _textEditingController.text;
    String javascriptCode = 'publishData("$data");';
    await _webViewController.evaluateJavascript(javascriptCode);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter WebView'),
      ),
      body: Column(
        children: [
          TextField(
            controller: _textEditingController,
            decoration: InputDecoration(
              labelText: 'Data',
            ),
          ),
          RaisedButton(
            onPressed: _publishDataToUrl,
            child: Text('Publish Data'),
          ),
          Expanded(
            child: WebView(
              initialUrl: 'https://example.com',
              javascriptMode: JavascriptMode.unrestricted,
              onWebViewCreated: (WebViewController controller) {
                _webViewController = controller;
              },
            ),
          ),
        ],
      ),
    );
  }
}