Flutter插件flutter_lwa的使用

flutter_lwa是一个用于在Flutter应用中集成“Login with Amazon”功能的插件，支持Android和iOS平台。以下是详细的使用步骤和示例代码。

安装

添加依赖到pubspec.yaml文件

首先，在项目的pubspec.yaml文件中添加flutter_lwa依赖：

dependencies:
  flutter_lwa: ^最新版本号

然后运行以下命令来获取包：

flutter pub get

登录Amazon配置

你需要在Amazon开发者控制台注册并创建API密钥。

Android设置

1. 在Amazon开发者控制台为Android创建一个API密钥。
2. 创建一个文本文件位于{project_root}/android/app/src/main/assets/api_key.txt。
3. 将从Amazon控制台获取的API密钥内容复制粘贴到{project_root}/android/app/src/main/assets/api_key.txt文件中。

iOS设置

1. 在Amazon开发者控制台为iOS创建一个API密钥。
2. 编辑{project_root}/ios/Runner/Info.plist文件，添加APIKey键值对（将{api_key}替换为你从Amazon控制台获取的API密钥）：

<key>APIKey</key>
<string>{api_key}</string>

1. 同样编辑{project_root}/ios/Runner/Info.plist文件，添加CFBundleURLTypes键值对（将{bundle_id}替换为你的应用程序的bundle标识符）：

<key>CFBundleURLTypes</key>
<array>
    <dict>
        <key>CFBundleURLName</key>
        <string>{bundle_id}</string>
        <key>CFBundleURLSchemes</key>
        <array>
            <string>amzn-{bundle_id}</string>
        </array>
    </dict>
</array>

1. 更新{project_root}/ios/Runner/AppDelegate.m文件，添加必要的导入语句和方法：

#import <LoginWithAmazon/LoginWithAmazon.h>

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application openURL:(NSURL *) url options:(NSDictionary<UIApplicationOpenURLOptionsKey,id> *)options {
    return [AMZNAuthorizationManager handleOpenURL:url
                                 sourceApplication:options[UIApplicationOpenURLOptionsSourceApplicationKey]];
}

@end

使用方法

该插件遵循与Google Signin API相同的模式以简化集成。以下是一个完整的示例代码：

import 'package:flutter/material.dart';
import 'package:flutter_lwa/lwa.dart';

void main() => runApp(MyApp());

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

class _MyAppState extends State<MyApp> {
  LwaAuthorizeResult _lwaAuth = LwaAuthorizeResult.empty();
  LwaUser _lwaUser = LwaUser.empty();

  final LoginWithAmazon _loginWithAmazon = LoginWithAmazon(
    scopes: <Scope>[ProfileScope.profile(), ProfileScope.postalCode()],
  );

  [@override](/user/override)
  void initState() {
    super.initState();
    _loginWithAmazon.onLwaAuthorizeChanged.listen((LwaAuthorizeResult auth) {
      setState(() {
        _lwaAuth = auth;
      });
      _fetchUserProfile();
    });
    _loginWithAmazon.signInSilently();
  }

  Future<void> _fetchUserProfile() async {
    if (_lwaAuth.isLoggedIn) {
      _lwaUser = await _loginWithAmazon.fetchUserProfile();
    } else {
      _lwaUser = LwaUser.empty();
    }
    setState(() {
      _lwaUser = _lwaUser;
    });
  }

  Future<void> _handleSignIn(BuildContext context) async {
    try {
      await _loginWithAmazon.signin();
    } catch (error) {
      ScaffoldMessenger.of(context).showSnackBar(SnackBar(
        content: Text(error.toString()),
      ));
    }
  }

  Future<void> _handleSignOut() => _loginWithAmazon.signOut();

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Sample Login with Amazon App'),
        ),
        body: Builder(
          builder: (BuildContext _context) {
            return _bodyView(_context);
          },
        ),
      ),
    );
  }

  Widget _bodyView(BuildContext context) {
    return _lwaAuth.isLoggedIn
        ? _loggedInWidgets()
        : _loggedOutWidgets(context);
  }

  Widget _loggedInWidgets() {
    return Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
      Container(
        padding: const EdgeInsets.fromLTRB(0, 0, 10, 0),
        child: Align(
          alignment: Alignment.topRight,
          child: TextButton(
            onPressed: _handleSignOut,
            child: const Text('Logout'),
          ),
        ),
      ),
      Expanded(
        child: Center(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(20, 0, 20, 0),
            child: Text(
              'Welcome, ${_lwaUser.userName}!\nYour email is ${_lwaUser.userEmail}\nYour zipCode is ${_lwaUser.userPostalCode}\n',
              maxLines: 6,
              textAlign: TextAlign.center,
            ),
          ),
        ),
      ),
    ]);
  }

  Widget _loggedOutWidgets(BuildContext context) {
    return Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
      const Expanded(
        child: Center(
          child: Padding(
            padding: EdgeInsets.fromLTRB(20, 0, 20, 0),
            child: Text(
              'Welcome to Login with Amazon!\nIf this is your first time logging in, you will be asked to give permission for this application to access your profile data.',
              maxLines: 6,
              textAlign: TextAlign.center,
            ),
          ),
        ),
      ),
      Container(
        padding: const EdgeInsets.fromLTRB(0, 10, 0, 30),
        child: LwaButton(onPressed: () => _handleSignIn(context)),
      ),
    ]);
  }
}