amazon_cognito_identity_dart 是一个用于在 Flutter 应用中与 AWS Cognito 进行身份认证的 Dart 插件。它允许你实现用户注册、登录、密码重置等功能。以下是如何在 Flutter 项目中使用 amazon_cognito_identity_dart 插件的步骤。

1. 添加依赖

首先，在 pubspec.yaml 文件中添加 amazon_cognito_identity_dart 依赖：

dependencies:
  flutter:
    sdk: flutter
  amazon_cognito_identity_dart: ^2.0.0

然后运行 flutter pub get 来安装依赖。

2. 配置 AWS Cognito

在 AWS 控制台中创建一个 Cognito 用户池，并获取以下信息：

• User Pool ID: 用户池的唯一标识符。
• Client ID: 用户池中应用的客户端 ID。

3. 初始化 Cognito 客户端

在你的 Flutter 应用中，初始化 Cognito 客户端：

import 'package:amazon_cognito_identity_dart_2/cognito.dart';

final userPool = CognitoUserPool(
  'YOUR_USER_POOL_ID',
  'YOUR_CLIENT_ID',
);

4. 用户注册

使用 CognitoUserPool 来注册新用户：

Future<void> signUp(String username, String password, String email) async {
  final userAttributes = [
    AttributeArg(name: 'email', value: email),
  ];

  try {
    final result = await userPool.signUp(username, password, userAttributes: userAttributes);
    print('User signed up: ${result.userSub}');
  } catch (e) {
    print('Error signing up: $e');
  }
}

5. 用户登录

使用 CognitoUser 来登录用户：

Future<void> signIn(String username, String password) async {
  final cognitoUser = CognitoUser(username, userPool);
  final authDetails = AuthenticationDetails(
    username: username,
    password: password,
  );

  try {
    final session = await cognitoUser.authenticateUser(authDetails);
    print('User signed in: ${session.accessToken.jwtToken}');
  } catch (e) {
    print('Error signing in: $e');
  }
}

6. 获取用户信息

登录后，你可以获取用户的详细信息：

Future<void> getUserInfo(CognitoUser cognitoUser) async {
  try {
    final attributes = await cognitoUser.getUserAttributes();
    attributes.forEach((attribute) {
      print('${attribute.name}: ${attribute.value}');
    });
  } catch (e) {
    print('Error getting user info: $e');
  }
}

7. 用户注销

注销用户：

Future<void> signOut(CognitoUser cognitoUser) async {
  try {
    await cognitoUser.signOut();
    print('User signed out');
  } catch (e) {
    print('Error signing out: $e');
  }
}

8. 密码重置

用户可以请求重置密码：

Future<void> resetPassword(String username) async {
  final cognitoUser = CognitoUser(username, userPool);

  try {
    await cognitoUser.forgotPassword();
    print('Password reset code sent');
  } catch (e) {
    print('Error resetting password: $e');
  }
}

9. 确认密码重置

用户输入验证码和新密码后，确认密码重置：

Future<void> confirmPasswordReset(String username, String verificationCode, String newPassword) async {
  final cognitoUser = CognitoUser(username, userPool);

  try {
    await cognitoUser.confirmPassword(verificationCode, newPassword);
    print('Password reset confirmed');
  } catch (e) {
    print('Error confirming password reset: $e');
  }
}

10. 处理会话

你可以检查用户是否已经登录，并获取会话信息：

Future<void> checkSession(CognitoUser cognitoUser) async {
  try {
    final session = await cognitoUser.getSession();
    if (session.isValid()) {
      print('User is logged in');
    } else {
      print('User is not logged in');
    }
  } catch (e) {
    print('Error checking session: $e');
  }
}

11. 刷新 Token

如果访问令牌过期，你可以刷新它：

Future<void> refreshToken(CognitoUser cognitoUser) async {
  try {
    final session = await cognitoUser.refreshSession();
    print('Token refreshed: ${session.accessToken.jwtToken}');
  } catch (e) {
    print('Error refreshing token: $e');
  }
}

12. 错误处理

在实际应用中，确保处理所有可能的错误，例如网络错误、用户输入错误等。

13. 完整示例

以下是一个完整的示例，展示了如何使用 amazon_cognito_identity_dart 进行用户注册、登录和注销：

import 'package:flutter/material.dart';
import 'package:amazon_cognito_identity_dart_2/cognito.dart';

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

class MyApp extends StatelessWidget {
  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: AuthScreen(),
    );
  }
}

class AuthScreen extends StatefulWidget {
  [@override](/user/override)
  _AuthScreenState createState() => _AuthScreenState();
}

class _AuthScreenState extends State<AuthScreen> {
  final userPool = CognitoUserPool('YOUR_USER_POOL_ID', 'YOUR_CLIENT_ID');
  final usernameController = TextEditingController();
  final passwordController = TextEditingController();
  final emailController = TextEditingController();

  Future<void> signUp() async {
    final userAttributes = [
      AttributeArg(name: 'email', value: emailController.text),
    ];

    try {
      final result = await userPool.signUp(usernameController.text, passwordController.text, userAttributes: userAttributes);
      print('User signed up: ${result.userSub}');
    } catch (e) {
      print('Error signing up: $e');
    }
  }

  Future<void> signIn() async {
    final cognitoUser = CognitoUser(usernameController.text, userPool);
    final authDetails = AuthenticationDetails(
      username: usernameController.text,
      password: passwordController.text,
    );

    try {
      final session = await cognitoUser.authenticateUser(authDetails);
      print('User signed in: ${session.accessToken.jwtToken}');
    } catch (e) {
      print('Error signing in: $e');
    }
  }

  Future<void> signOut(CognitoUser cognitoUser) async {
    try {
      await cognitoUser.signOut();
      print('User signed out');
    } catch (e) {
      print('Error signing out: $e');
    }
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('AWS Cognito Auth'),
      ),
      body: Padding(
        padding: const EdgeInsets.all(16.0),
        child: Column(
          children: [
            TextField(
              controller: usernameController,
              decoration: InputDecoration(labelText: 'Username'),
            ),
            TextField(
              controller: passwordController,
              decoration: InputDecoration(labelText: 'Password'),
              obscureText: true,
            ),
            TextField(
              controller: emailController,
              decoration: InputDecoration(labelText: 'Email'),
            ),
            SizedBox(height: 20),
            ElevatedButton(
              onPressed: signUp,
              child: Text('Sign Up'),
            ),
            ElevatedButton(
              onPressed: signIn,
              child: Text('Sign In'),
            ),
          ],
        ),
      ),
    );
  }
}