1. 首先创建项目结构：

fashion_store/
├── backend/
│   ├── app/
│   │   ├── __init__.py
│   │   ├── models/
│   │   ├── routes/
│   │   ├── services/
│   │   └── utils/
│   ├── config.py
│   ├── requirements.txt
│   └── run.py
└── frontend/
    ├── android/
    ├── ios/
    ├── lib/
    │   ├── main.dart
    │   ├── screens/
    │   ├── widgets/
    │   └── services/
    └── pubspec.yaml

2. 后端核心代码：

# backend/requirements.txt
flask==2.0.1
flask-sqlalchemy==2.5.1
flask-cors==3.0.10
opencv-python==4.5.3.56
numpy==1.21.2
pillow==8.3.2

# backend/config.py
class Config:
    SQLALCHEMY_DATABASE_URI = 'sqlite:///fashion_store.db'
    SQLALCHEMY_TRACK_MODIFICATIONS = False
    SECRET_KEY = 'your-secret-key'
    UPLOAD_FOLDER = 'uploads'

# backend/app/__init__.py
from flask import Flask
from flask_sqlalchemy import SQLAlchemy
from flask_cors import CORS
from config import Config

db = SQLAlchemy()

def create_app():
    app = Flask(__name__)
    app.config.from_object(Config)
    
    CORS(app)
    db.init_app(app)
    
    from app.routes import main_bp
    app.register_blueprint(main_bp)
    
    return app

# backend/app/models/user.py
from app import db

class User(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    username = db.Column(db.String(80), unique=True, nullable=False)
    email = db.Column(db.String(120), unique=True, nullable=False)
    password_hash = db.Column(db.String(128))
    preferences = db.Column(db.JSON)

class Product(db.Model):
    id = db.Column(db.Integer, primary_key=True)
    name = db.Column(db.String(100), nullable=False)
    description = db.Column(db.Text)
    price = db.Column(db.Float, nullable=False)
    image_url = db.Column(db.String(200))
    category = db.Column(db.String(50))
    ar_model_url = db.Column(db.String(200))

# backend/app/services/recommendation.py
import numpy as np

class RecommendationService:
    def __init__(self):
        self.model = None  # 这里可以加载预训练的推荐模型
        
    def get_recommendations(self, user_id):
        # 示例推荐逻辑
        from app.models import Product
        products = Product.query.all()
        return np.random.choice(products, 5, replace=False)

# backend/app/services/virtual_fitting.py
import cv2
import numpy as np

class VirtualFittingService:
    def process_image(self, user_image, product_image):
        # 简化版虚拟试衣逻辑
        user_img = cv2.imread(user_image)
        product_img = cv2.imread(product_image)
        
        # 这里应该有更复杂的AR处理逻辑
        result = cv2.addWeighted(user_img, 0.7, product_img, 0.3, 0)
        
        return result

3. 前端核心代码：

# frontend/pubspec.yaml
name: fashion_store
description: A fashion store app with AR fitting room

dependencies:
  flutter:
    sdk: flutter
  http: ^0.13.3
  camera: ^0.9.4
  ar_flutter_plugin: ^0.6.2
  provider: ^6.0.1

// frontend/lib/main.dart
import 'package:flutter/material.dart';
import 'package:fashion_store/screens/home_screen.dart';

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

class FashionStore extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: '时尚购物',
      theme: ThemeData(
        primarySwatch: Colors.pink,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: HomeScreen(),
    );
  }
}

// frontend/lib/screens/home_screen.dart
import 'package:flutter/material.dart';
import '../widgets/product_grid.dart';
import '../widgets/recommendation_section.dart';

class HomeScreen extends StatefulWidget {
  @override
  _HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  int _selectedIndex = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('时尚购物'),
        actions: [
          IconButton(
            icon: Icon(Icons.shopping_cart),
            onPressed: () {
              // 打开购物车
            },
          ),
        ],
      ),
      body: IndexedStack(
        index: _selectedIndex,
        children: [
          HomeTab(),
          CategoryTab(),
          VirtualFittingTab(),
          ProfileTab(),
        ],
      ),
      bottomNavigationBar: BottomNavigationBar(
        items: [
          BottomNavigationBarItem(icon: Icon(Icons.home), label: '首页'),
          BottomNavigationBarItem(icon: Icon(Icons.category), label: '分类'),
          BottomNavigationBarItem(icon: Icon(Icons.camera), label: '试衣间'),
          BottomNavigationBarItem(icon: Icon(Icons.person), label: '我的'),
        ],
        currentIndex: _selectedIndex,
        onTap: (index) => setState(() => _selectedIndex = index),
      ),
    );
  }
}

4. 将代码导出为APP的步骤：

1. 后端部署：

# 在服务器上
cd backend
pip install -r requirements.txt
python run.py

2. 前端打包Android APK：

cd frontend
flutter build apk --release

3. 前端打包iOS IPA：

cd frontend
flutter build ios --release

要生成完整可用的APP，还需要：

1. 配置服务器环境

# 安装必要的系统依赖
sudo apt-get update
sudo apt-get install python3-pip python3-dev nginx

2. 设置nginx配置：

server {
    listen 80;
    server_name your_domain.com;

    location / {
        proxy_pass http://127.0.0.1:5000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
}

3. 使用gunicorn运行Flask应用：

pip install gunicorn
gunicorn -w 4 -b 127.0.0.1:5000 run:app

本案例还需要注意补充以下功能模块和注意事项：

1. 需要配置真实的数据库连接
2. 需要实现完整的用户认证系统
3. 需要添加适当的错误处理
4. 需要实现数据缓存机制
5. 需要添加日志系统
6. 需要实现完整的支付系统
7. 需要添加商品管理后台
8. 需要实现图片上传和存储功能