接收有关Flutter中新数据输入的通知

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('StreamBuilder Example')),
        body: StreamBuilderExample(),
      ),
    );
  }
}

class StreamBuilderExample extends StatefulWidget {
  @override
  _StreamBuilderExampleState createState() => _StreamBuilderExampleState();
}

class _StreamBuilderExampleState extends State<StreamBuilderExample> {
  final _controller = TextEditingController();
  final _streamController = StreamController<String>.broadcast();

  @override
  void initState() {
    super.initState();
    _controller.addListener(_onTextChanged);
  }

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

  void _onTextChanged() {
    _streamController.add(_controller.text);
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        StreamBuilder<String>(
          stream: _streamController.stream,
          builder: (context, snapshot) {
            return Text('You entered: ${snapshot.data}');
          },
        ),
        TextField(
          controller: _controller,
        ),
      ],
    );
  }
}