How to implement the Java switch grocery shopping system with flash sale function

In today’s e-commerce market, flash sale activities have great market decision-making ability. In order to win market share, various merchants have implemented large-scale and high-frequency flash sales activities. For this kind of activity, implementing a relatively complete system in the background can not only ensure the stability of the system, but also win higher benefits for merchants.

This article will introduce how to implement a simple flash sale function in Java open source distributed cache, and take the switch of the grocery shopping system as an example.

Step 1: Business analysis and demand planning

Through the business analysis of the flash sale activity of the switch grocery shopping system, we can determine the system requirements that need to be implemented:

1. Every A user can only purchase an item once.

2. When the flash sale event starts, all products that can be flash sale should be preloaded in the cache.

3. Before the flash sale starts, it is limited by a switch. When the switch is turned on, the client can initiate a flash sale request.

4. When the product inventory quantity reaches 0, the flash sale activity ends automatically.

Based on the above requirements, we have formulated high-priority and low-priority requirements, as well as a continuous iterative demand plan.

Step 2: Technology selection and system design

We choose Java open source distributed cache Ehcache and SpringMVC as the technology stack of this system. In terms of system design, we divide the flash sale activity implementation into two modules, namely loading cache and flash sale process.

Load cache module:

Before the flash sale event starts, the information (name, quantity, price, etc.) of the flash sale product needs to be loaded into the cache in advance. This module needs to complete three steps:

1. Read the flash sale product information from the database;

2. Store the read product information in the Ehcache cache;

3. Use a timer to regularly refresh flash sale product information in Ehcache.

Second Kill Process Module:

When the Flash Sale starts, the client can request the Flash Kill interface, and the system will process the Flash Kill request. This module needs to complete the following four steps:

1. Obtain product information from the cache;

2. Verify whether the user meets the requirements of the flash sale activity;

3. Deduct the quantity of goods;

4. Generate an order and complete the purchase.

Step 3: Code implementation

In the implementation code, we use the SpringMVC framework as the basis, and use Ehcache, Mybatis and other frameworks to complete various functional modules developed in Java.

Loading cache module implementation:

@Service
public class GoodsServiceImpl implements GoodsService {

    @Autowired
    private GoodsMapper goodsMapper;

    @Autowired
    private GoodsCacheService goodsCacheService;

    // 缓存key值
    private static final String CACHE_NAME = "goods";

    @Override
    public void preLoadGoods() {
        // 获取所有秒杀商品的信息
        List<Goods> goodsList = goodsMapper.selectSecKillGoodsList();
        // 遍历并将商品信息存入缓存
        for (Goods goods : goodsList) {
            goodsCacheService.put(CACHE_NAME, String.valueOf(goods.getGoodsId()), goods);
        }
        // 周期性刷新缓存中的商品信息
        TimerTask task = new TimerTask() {
            @Override
            public void run() {
                List<Goods> goodsList = goodsMapper.selectSecKillGoodsList();
                for (Goods goods : goodsList) {
                    goodsCacheService.put(CACHE_NAME, String.valueOf(goods.getGoodsId()), goods);
                }
            }
        };
        Timer timer = new Timer();
        timer.schedule(task, 0, 1000 * 60 * 5); //5分钟刷新一次
        // 缓存预热结束
        log.info("缓存预热结束");
    }

}

Flash sale process module implementation:

@Service
public class SecKillServiceImpl implements SecKillService {

    @Autowired
    private GoodsCacheService goodsCacheService;

    @Autowired
    private OrderService orderService;

    @Override
    public void secKill(User user, int goodsId) throws SecKillException {
        // 从缓存中获取商品信息
        Goods goods = goodsCacheService.get("goods", String.valueOf(goodsId));
        if (goods.getGoodsCount() <= 0) {
            throw new SecKillException("商品已售罄！");
        }
        // 判断用户是否可参与秒杀活动
        Order order = orderService.getOrderByUserIdAndGoodsId(user.getUserId(), goodsId);
        if (order != null) {
            throw new SecKillException("每个用户只能秒杀一次！");
        }
        // 扣减商品库存
        int result = goodsCacheService.decrease("goods", String.valueOf(goodsId), 1);
        if (result <= 0) {
            throw new SecKillException("商品已售罄！");
        }
        // 生成订单
        orderService.createOrder(user.getUserId(), goodsId, goods.getGoodsPrice());
    }

}

Step 4: Project test

After code implementation, we need to carry out system test. In testing, we simulated a user performing a limit test at the start of a flash sale. The test results show that our system can maintain stability and throughput well under large concurrency conditions.

Step 5: Summary

Through the introduction of this article, everyone should understand how to implement a simple flash sale activity system in the Java open source distributed cache Ehcache. It is worth noting that during actual development, more detailed code planning and testing are required to ensure the stability and timeliness of the system.

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