如何在dart/flutter中收听流值

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

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

class MyApp extends StatelessWidget {
  final StreamController<String> _streamController = StreamController<String>();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Stream Example'),
        ),
        body: Center(
          child: StreamBuilder<String>(
            stream: _streamController.stream,
            builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
              if (snapshot.hasData) {
                return Text('Received data: ${snapshot.data}');
              } else {
                return Text('Waiting for data...');
              }
            },
          ),
        ),
        floatingActionButton: FloatingActionButton(
          onPressed: () {
            _streamController.sink.add('Hello, World!');
          },
          child: Icon(Icons.send),
        ),
      ),
    );
  }

  @override
  void dispose() {
    _streamController.close();
    super.dispose();
  }
}