我将尝试首先解释BLOC组件应该做的越短越好（并且越琐碎）。

• UI屏幕-显然向用户显示数据
• BLOC（或ViewModel）-决定如何向用户显示数据，是否使文本加粗，是否显示错误，是否转到下一个屏幕。
• 回购-决定向用户显示什么数据（我们是否从db中显示内容，是否从API中获取内容，是否显示红色产品？）

您还可以根据您的应用程序执行其他操作，例如：

• 联网-执行API请求并转换对模型的响应，这只能从回购协议访问，并且该组件唯一要做的就是从回购协议（标头，正文，URL）接收数据，并以形式将数据返回回回购协议模型（您可以查看下面的代码）。
• 数据库-对数据库执行CRUD操作，只能从仓库访问。
• 传感器-从本地传感器读取数据，只能从回购中访问。

现在，我建议也将BLOC模式与Dependency
Injection一起使用，没有它是没有用的。使用DI，您可以模拟所有组件直到UI，并且对所有代码进行单元测试非常容易。

另外，我认为没有必要将RxDart（library）与Streams / Future（相当于RxDart
lib的dat）混合使用。首先，我建议仅使用其中之一，并根据您的代码片段，建议您更好地了解如何整体使用Rx。

因此，下面有一个关于如何使用块模式进行登录的小代码片段（也可以检查代码注释:)）。

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;

class TheUIScreen extends StatefulWidget {
  @override
  _TheUIScreenState createState() => _TheUIScreenState();
}

class _TheUIScreenState extends State<TheUIScreen> {
  //TODO: for repo, block, networking, we used dependecy injection, here we have to create and init all the dependecies;

  TheAuthBlock _block;

  @override
  void initState() {
    super.initState();
    TheAuthAPI api = TheAuthAPI();
    TheAuthRepo repo =
        TheAuthRepo(theAuthAPI: api); // we could also do repo = TheAuthRepo();
    _block =
        TheAuthBlock(repo: repo); // we could also do _block = TheAuthBlock();
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      child: RaisedButton(onPressed: () {
        _block.loginUser("test", "test").then((actualUser) {
          Navigator.of(context).push(MaterialPageRoute(builder: (context) {
            return TestRoute(); // or do whatever action you need, the user is logged in
          }));
        }).catchError((error) {
          //show error, something went wrong at login;
        });
      }),
    );
  }
}

class TheAuthBlock {
  final TheAuthRepo repo;

  TheAuthBlock({this.repo = const TheAuthRepo()});

  Future<UserModel> loginUser(String email, String password) {
    return repo.login(email, password).then((userModel) {
      //TODO: here we decide HOW to display the user, you might want to transfor the UserModel into a model that's used only for UI.
      //In any way, here you should do all the processing, the UI only should only display the data, not manipulate it.
    });
  }
}

class TheAuthRepo {
  final TheAuthAPI theAuthAPI;

  const TheAuthRepo(
      {this.theAuthAPI =
          const TheAuthAPI()}); // THIS would be the default constructor but it will alow us to test it using unit tests.

  Future<UserModel> login(String email, String password) {
    //TODO: here you could also check if the user is already logged in and send the current user as a response
    if (email.isNotEmpty && password.isNotEmpty) {
      return theAuthAPI.login(email, password).then((userModel) {
        //TODO: you can do extra processing here before returning the data to the block;
      });
    } else {
      return Future.error(
          "Well you can't login with empty ddata"); // TODO: you can return differetn errors for email or pwd;
    }
  }
}

class TheAuthAPI {
  final String url;

  const TheAuthAPI({this.url = "https://my.cool.api/login"});

  Future<UserModel> login(String email, String pwd) {
    // TODO: note you return a future from this method since the login will return only once (like almost all http calls)
    Map<String, String> headers = Map(); // TODO: set any headers you need here
    Map<String, String> body = {
      "email": email,
      "pwd": pwd
    }; // TODO: change the body acordingly
    return http.post("THE URL", headers: headers, body: body).then((response) {
      //TODO: parse response here and return it
      return UserModel("test",
          "test"); // this should be generated from the response not like this
    });
  }
}

class UserModel {
  final String email;

  UserModel(this.email, this.pass);

  final String pass;
}