Android 为什么Flatter导入提供程序包不工作？

因此，请遵循本教程，在Flatter中创建一个简单的登录UI

很明显，这个颤振包装没有正确进口。不起作用的特定行是这3行代码

import 'package:provider/provider.dart';
ChangeNotifierProvider<AuthService>( //TODO: authservices and provider pages
future: Provider.of<AuthService>(context).getUser(),

导入“包：provider/provider.dart”； ChangeNotifierProvider（//TODO:authservices和提供程序页 future:Provider.of（context.getUser（）， 我一直在搜索一堆文件，并试图阅读这些文件，但无法得到任何简单的答案，但无论如何，感谢所有给我答案的人

import 'package:flutter/material.dart';
    import 'package:provider/provider.dart';
    import 'home_page.dart';
    import 'auth.dart';
    import 'login_page.dart';

void main() => runApp(
  ChangeNotifierProvider<AuthService>( //TODO: authservices and provider pages
    child: MyApp(),
    builder: (BuildContext context) {
      return AuthService();
    },
  ),
);

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(primarySwatch: Colors.blue),
      home: FutureBuilder(
        future: Provider.of<AuthService>(context).getUser(),
        builder: (context, AsyncSnapshot snapshot) {
          if (snapshot.connectionState == ConnectionState.done) {
            return snapshot.hasData ? HomePage() : LoginPage();
          } else {
            return Container(color: Colors.white);
          }
        },
      ),
    );
  }
}

导入“包装：颤振/材料.省道”；
导入“包：provider/provider.dart”；
导入“主页.省道”；
导入“auth.dart”；
导入“login_page.dart”；
void main（）=>runApp(
ChangeNotifierProvider（//TODO:authservices和提供程序页
子项：MyApp（），
生成器：（BuildContext上下文）{
返回AuthService（）；
},
),
);
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@凌驾
小部件构建（构建上下文）{
返回材料PP(
标题：“颤振演示”，
主题：主题数据（原始样本：颜色。蓝色），
家：未来建设者(
future:Provider.of（context.getUser（），
生成器：（上下文，异步快照）{
if（snapshot.connectionState==connectionState.done）{
返回snapshot.hasData？主页（）：LoginPage（）；
}否则{
返回容器（颜色：颜色.白色）；
}
},
),
);
}
}

pubspec.yaml文件供任何人查看

name: login_flutter_app
description: A new Flutter application.

# The following defines the version and build number for your application.
# A version number is three numbers separated by dots, like 1.2.43
# followed by an optional build number separated by a +.
# Both the version and the builder number may be overridden in flutter
# build by specifying --build-name and --build-number, respectively.
# In Android, build-name is used as versionName while build-number used as versionCode.
# Read more about Android versioning at https://developer.android.com/studio/publish/versioning
# In iOS, build-name is used as CFBundleShortVersionString while build-number used as CFBundleVersion.
# Read more about iOS versioning at
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
version: 1.0.0+1

environment:
  sdk: ">=2.1.0 <3.0.0"

dependencies:
  flutter:
    sdk: flutter

  # The following adds the Cupertino Icons font to your application.
  # Use with the CupertinoIcons class for iOS style icons.
  cupertino_icons: ^0.1.2

dev_dependencies:
  flutter_test:
    sdk: flutter


# For information on the generic Dart part of this file, see the
# following page: https://dart.dev/tools/pub/pubspec

# The following section is specific to Flutter.
flutter:

  # The following line ensures that the Material Icons font is
  # included with your application, so that you can use the icons in
  # the material Icons class.
  uses-material-design: true

  # To add assets to your application, add an assets section, like this:
  # assets:
  #  - images/a_dot_burr.jpeg
  #  - images/a_dot_ham.jpeg

  # An image asset can refer to one or more resolution-specific "variants", see
  # https://flutter.dev/assets-and-images/#resolution-aware.

  # For details regarding adding assets from package dependencies, see
  # https://flutter.dev/assets-and-images/#from-packages

  # To add custom fonts to your application, add a fonts section here,
  # in this "flutter" section. Each entry in this list should have a
  # "family" key with the font family name, and a "fonts" key with a
  # list giving the asset and other descriptors for the font. For
  # example:
  # fonts:
  #   - family: Schyler
  #     fonts:
  #       - asset: fonts/Schyler-Regular.ttf
  #       - asset: fonts/Schyler-Italic.ttf
  #         style: italic
  #   - family: Trajan Pro
  #     fonts:
  #       - asset: fonts/TrajanPro.ttf
  #       - asset: fonts/TrajanPro_Bold.ttf
  #         weight: 700
  #
  # For details regarding fonts from package dependencies,
  # see https://flutter.dev/custom-fonts/#from-packages

name:login\u flatter\u应用程序
描述：一个新的颤振应用。
#下面定义了应用程序的版本和内部版本号。
#版本号是由点分隔的三个数字，如1.2.43
#后跟可选的内部版本号，以+分隔。
#版本和制造商编号都可能在颤振中被覆盖
#通过分别指定--build name和--build number来生成。
#在Android中，版本名用作版本名，而版本号用作版本代码。
#更多关于Android版本控制的信息，请访问https://developer.android.com/studio/publish/versioning
#在iOS中，生成名称用作CbundleShortVersionString，而生成编号用作CbundLeverVersion。
#阅读有关iOS版本控制的更多信息，请访问
# https://developer.apple.com/library/archive/documentation/General/Reference/InfoPlistKeyReference/Articles/CoreFoundationKeys.html
版本：1.0.0+1
环境：
sdk:“>=2.1.0必须将这些应用到项目中

cupertino_图标：^0.1.2
颤振蓝色：^0.6.3+1
提供程序：^4.0.4

必须把这些投入到项目中

cupertino_图标：^0.1.2
颤振蓝色：^0.6.3+1
提供程序：^4.0.4

只需将依赖项提供程序：^4.1.1添加到pubspec.yaml文件中。它看起来像下面这样

dependencies:
  flutter:
   sdk: flutter
  provider: ^4.1.1

只需将依赖项提供程序：^4.1.1添加到pubspec.yaml文件中。它看起来像下面这样

dependencies:
  flutter:
   sdk: flutter
  provider: ^4.1.1

您的
pubspec.yaml
看起来像什么？
名称：登录\u flatter\u应用程序描述：一个新的flatter应用程序。版本：1.0.0+1环境：sdk:：>=2.1.0我删除了大部分评论，但这就是它看起来的样子。你需要在你的pubspec.yaml依赖项中包含提供者。你的
pubspec.yaml
看起来像什么？
name:login\u flatter\u应用程序描述：一个新的flatter应用程序。版本：1.0.0+1环境：sdk:“>=2.1.0我删除了大部分注释，但这就是您需要在pubspec.yaml依赖项中包含提供者的情况