核心：避免超卖问题，保证一人一单 业务逻辑
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@Service public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService { @Resource private ISeckillVoucherService seckillVoucherService; @Resource private RedisIdWorker redisIdWorker; @Resource private StringRedisTemplate stringRedisTemplate; @Resource private RedissonClient redissonClient; @Override public Result seckillVoucher(Long voucherId) { //1 查询优惠券信息 SeckillVoucher seckillVoucher = seckillVoucherService.getById(voucherId); //2 判断秒杀是否开始 LocalDateTime now = LocalDateTime.now(); //现在时间 LocalDateTime beginTime = seckillVoucher.getBeginTime(); //开始时间 LocalDateTime endTime = seckillVoucher.getEndTime(); //结束时间 if (now.isBefore(beginTime)) { return Result.fail("秒杀还未开始"); } //3 判断秒杀是否结束 if (now.isAfter(endTime)) { return Result.fail("秒杀已结束"); } //4 判断库存是否充足 int stock = (int) seckillVoucher.getStock(); if (stock == 0 && stock <= 0) { return Result.fail("库存不足"); } //确保一人一单 用户ID和代金券ID联合查询 Long userId = UserHolder.getUser().getId(); //先获取锁 再提交事务 //synchronized (userId.toString().intern()) { //创建锁对象 //SimpleRedisLock simpleRedisLock = new SimpleRedisLock("order:" + userId, stringRedisTemplate); RLock lock = redissonClient.getLock("lock:order:" + userId); //获取锁 boolean isLock = lock.tryLock(); //判断是否获取锁成功 if (!isLock){ //获取锁失败 返回错误或失败 return Result.fail("不允许重复下单"); } try { //获取事务的代理对象 IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy(); return proxy.creatVoucherOrder(voucherId); } finally { //释放锁 lock.unlock(); } //}//事务提交之后在释放锁 } /** * 这里对于加锁做出一些解释：如果锁加在整个方法上，那么就会导 * 致锁的粒度过大，导致每个进程进来都会锁住，所以要控制锁的粒度 */ @Transactional public Result creatVoucherOrder(Long voucherId) { Long userId = UserHolder.getUser().getId(); Integer count = query().eq("user_id", userId).eq("voucher_id", voucherId).count(); if (count > 0) { return Result.fail("用户已经购买过了"); } //5 扣减库存- boolean success = seckillVoucherService.update() .setSql("stock = stock -1 ") //乐观锁 .eq("voucher_id", voucherId).gt("stock", 0) //判断库存是否大于0: where id = ? and stock > 0 .update(); if (!success) { return Result.fail("库存不足"); } //6 创建订单 //6.1 订单ID VoucherOrder voucherOrder = new VoucherOrder(); long orderid = RedisIdWorker.nextId("order"); voucherOrder.setVoucherId(orderid); //6.2 用户ID voucherOrder.setUserId(userId); //6.3 代金券ID voucherOrder.setVoucherId(voucherId); save(voucherOrder); //7 返回订单id return Result.ok(orderid); } } |
