如何在flutter中将语音传递到文本域？

import 'package:flutter/material.dart';
import 'package:speech_to_text/speech_to_text.dart' as stt;

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

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  stt.SpeechToText _speech;
  bool _isListening = false;
  String _text = '';

  @override
  void initState() {
    super.initState();
    _speech = stt.SpeechToText();
  }

  void _listen() async {
    if (!_isListening) {
      bool available = await _speech.initialize();
      if (available) {
        setState(() => _isListening = true);
        _speech.listen(
          onResult: (result) => setState(() {
            _text = result.recognizedWords;
          }),
        );
      }
    } else {
      setState(() => _isListening = false);
      _speech.stop();
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Speech to Text Demo'),
        ),
        body: Center(
          child: Column(
            children: [
              Text(_text),
              RaisedButton(
                child: Text(_isListening ? 'Stop' : 'Start'),
                onPressed: _listen,
              ),
            ],
          ),
        ),
      ),
    );
  }
}