Provider

共享数据类的写法：

示例：

class Bloc {
  final StreamController<String> _streamController = StreamController();
  Stream<String> stream;

  Bloc() {
  stream = _streamController.stream.asBroadcastStream();
  }

  void dispose() {
    _streamController.close();
  }
}

在构造方法里面写赋值语句，在类里面写变量声明。可以声明数据流。

记得要dispose。

如果引用provider的话，一定要把方法里面的builder和dispose属性补齐；就这么写就可以了；

Provider<Bloc>(
  builder: (_) => Bloc(),
  dispose: (_, value) => value.dispose(),
  child: Example(),
);

引用Provider数据：

Provider.of<Bloc>(context)._streamController.add(‘caolegequde‘);
这个里面的<Bloc>不可以忽略掉。

完整示例：

import ‘dart:async‘;
import ‘package:flutter/material.dart‘;
import ‘package:flutter/widgets.dart‘;
import ‘package:provider/provider.dart‘;

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

class Bloc {
  final StreamController<String> _streamController = StreamController();
  Stream<String> stream;

  Bloc() {
  stream = _streamController.stream.asBroadcastStream();
  }

  void dispose() {
    _streamController.close();
  }
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Provider<Bloc>(
      builder: (_) => Bloc(),
      dispose: (_, value) => value.dispose(),
      child: Example(),
    );
  }
}

class Example extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        floatingActionButton: FloatingActionButton(
          child: Icon(Icons.send),
          onPressed: (){
            Provider.of<Bloc>(context)._streamController.add(‘caolegequde‘);
          },
        ),
        appBar: AppBar(title: Text(‘ProviderDemo‘),),
        body: StreamBuilder<String>(
          stream: Provider.of<Bloc>(context).stream,
          builder: (context, snapshot) {
            return Text(snapshot.data?.toString() ?? ‘dashazinigeerhuo‘);
          },
        ),
      ),
    );
  }
}

Provider

原文：https://www.cnblogs.com/braveheart007/p/10837557.html