1. 前言

目的：该项目只用于技术交流，不用于过多商业用途。

适用：可用于简历亮点、毕业答辩等。

2. 项目成果

2.1 秒杀主页

包含5个功能点：

①、Product Name：秒杀商品名称

②、Product Image：秒杀商品图片

③、Price：秒杀价格

④、Seckill starts in：距离秒杀所剩时间

⑤、Seckill Now：秒杀按钮（核心逻辑）

部分不重要参数，没有做UI设计，只为功能而生。

2.2 秒杀架构

①、MySQL主从复制：一主二从

②、Redis缓存、Redis分布式锁

③、MQ异步处理库存、订单

3. 核心代码讲解

3.1 缓存预热

@Override
public void afterPropertiesSet() throws Exception {

    // 缓存秒杀商品
    List<SeckillGoods> seckillGoodsList = seckillMapper.queryAllSeckillGoods();
    for(SeckillGoods goods : seckillGoodsList) {
        String goodsId = goods.getId();
        Integer stock = goods.getGoodsStock();
        HashOperations hashOperations = redisTemplate.opsForHash();
        hashOperations.put(CONSTANT.SECKILLGOODS, goodsId, stock);
    }

    // 缓存秒杀订单
    List<SeckillOrder> seckillOrderList = seckillMapper.queryAllSeckillOrder();
    for(SeckillOrder seckillOrder : seckillOrderList) {
        String userId = seckillOrder.getUserId();
        String goodsId = seckillOrder.getGoodsId();
        HashOperations hashOperations = redisTemplate.opsForHash();
        hashOperations.put(CONSTANT.SECKILLORDER, userId + "," + goodsId, CONSTANT.SECKILLORDER);
    }

}

3.2 核心业务逻辑

@Override
public Map<String, String> buySeckillGoods(String userId, String goodsId) {

    Map result = new HashMap<String, String>();

    RLock lock = redisson.getLock(CONSTANT.SECKILLLOCK); // 拿不到会自己阻塞

    try {
        lock.lock();
        // 检查Redis秒杀商品是否有库存
        Integer stock = (Integer) redisTemplate.opsForHash().get(CONSTANT.SECKILLGOODS, goodsId);
        if(stock <= 0) {
            result.put("msg", "秒杀商品库存不足！");
            result.put("success", "400");
            return result;
        }

        // 检查该用户是否秒杀过该商品
        Object orderConstant = redisTemplate.opsForHash().get(CONSTANT.SECKILLORDER, userId + "," + goodsId);
        if(orderConstant != null) {
            result.put("msg", "该用户已经秒杀过该商品了！");
            result.put("success", "400");
            return result;
        }

        // Redis新增订单
        String orderId = UUID.randomUUID().toString();
        SeckillOrder seckillOrder = new SeckillOrder();
        seckillOrder.setId(orderId);
        seckillOrder.setGoodsId(goodsId);
        seckillOrder.setUserId(userId);

        redisTemplate.opsForHash().put(CONSTANT.SECKILLORDER, userId + "," + goodsId, CONSTANT.SECKILLORDER);

        // Redis减少库存
        redisTemplate.opsForHash().put(CONSTANT.SECKILLGOODS, goodsId, stock-1);

        // MQ处理库存和订单
        rabbitTemplate.convertAndSend("seckillGoodsExchange", "seckillGoodsRouting", seckillOrder);
        rabbitTemplate.convertAndSend("seckillOrderExchange", "seckillOrderRouting", seckillOrder);

    }catch (Exception e) {
        e.printStackTrace();
    }finally {
        lock.unlock(); // 解锁
    }

    result.put("msg", "秒杀商品成功！");
    result.put("success", "200");
    return result;
}