Redis高并发防止秒杀超卖实战源码解决方案

seckill_vouchers("seckill_vouchers:","秒杀券的 key"),

@Service
public class SeckillService {
@Resource
private SeckillVouchersMapper seckillVouchersMapper;
@Resource
2private VoucherOrdersMapper voucherOrdersMapper;
@Value("${service.name.ms-oauth-server}")
private String oauthServerName;
@Resource
private RestTemplate restTemplate;
@Resource
private RedisTemplate redisTemplate;

@Transactional(rollbackFor = Exception.class)
public void addSeckillVouchers(SeckillVouchers seckillVouchers) {
// 非空校验
AssertUtil.isTrue(seckillVouchers.getFkVoucherId()== null,"请选择需要抢购的代金券");
AssertUtil.isTrue(seckillVouchers.getAmount()== 0,"请输入抢购总数量");
Date now = new Date();
AssertUtil.isNotNull(seckillVouchers.getStartTime(),"请输入开始时间");
 
// 生产环境下面一行代码需放行，这里注释方便测试
// AssertUtil.isTrue(now.after(seckillVouchers.getStartTime()),"开始时间不能早于当前时间");
AssertUtil.isNotNull(seckillVouchers.getEndTime(),"请输入结束时间");
AssertUtil.isTrue(now.after(seckillVouchers.getEndTime()),"结束时间不能早于当前时间");
AssertUtil.isTrue(seckillVouchers.getStartTime().after(seckillVouchers.getEndTime()),"开始时间不能晚于结束时间");
 
// 采用 Redis 实现
String key= RedisKeyConstant.seckill_vouchers.getKey() +seckillVouchers.getFkVoucherId();
// 验证 Redis 中是否已经存在该券的秒杀活动,hash 不会做序列化和反序列化，
有利于性能的提高。entries(key），取到 key
Map<String, Object> map= redisTemplate.opsForHash().entries(key);
//如果不为空或 amount 库存>0,该券已经拥有了抢购活动,就不要再创建。
AssertUtil.isTrue(!map.isEmpty() && (int) map.get("amount") > 0,"该券已经拥有了抢购活动");
 
// 抢购活动数据插入 Redis
seckillVouchers.setIsValid(1);
seckillVouchers.setCreateDate(now);
seckillVouchers.setUpdateDate(now);
//key 对应的是 map,使用工具集将 seckillVouchers 转成 map
redisTemplate.opsForHash().putAll(key,BeanUtil.beanToMap(seckillVouchers));
}

@Transactional(rollbackFor = Exception.class)
public ResultInfo doSeckill(Integer voucherId, String accessToken, String path)
{
// 基本参数校验
AssertUtil.isTrue(voucherId == null || voucherId < 0,"请选择需要抢购的代金券");
AssertUtil.isNotEmpty(accessToken,"请登录");
 
// 采用 Redis
String key= RedisKeyConstant.seckill_vouchers.getKey() + voucherId;//根据 key 获取 map
Map<String, Object> map= redisTemplate.opsForHash().entries(key);
//map 转对象
SeckillVouchers seckillVouchers = BeanUtil.mapToBean(map,SeckillVouchers.class, true, null);
 
// 判断是否开始、结束
Date now = new Date();
AssertUtil.isTrue(now.before(seckillVouchers.getStartTime()),"该抢购还未开始");
AssertUtil.isTrue(now.after(seckillVouchers.getEndTime()),"该抢购已结束");
 
// 判断是否卖完
AssertUtil.isTrue(seckillVouchers.getAmount() < 1,"该券已经卖完了");
 
// 获取登录用户信息
String url = oauthServerName +"user/me?access_token={accessToken}";
ResultInfo resultInfo = restTemplate.getForObject(url, ResultInfo.class,accessToken);
if (resultInfo.getCode() != ApiConstant.SUCCESS_CODE) {
resultInfo.setPath(path);
return resultInfo;
}
 
// 这里的 data 是一个 LinkedHashMap，SignInDinerInfo
SignInDinerInfo dinerInfo = BeanUtil.fillBeanWithMap((LinkedHashMap)resultInfo.getData(), new SignInDinerInfo(), false);
 
// 判断登录用户是否已抢到(一个用户针对这次活动只能买一次)
VoucherOrders order =voucherOrdersMapper.findDinerOrder(dinerInfo.getId(),seckillVouchers.getFkVoucherId());
AssertUtil.isTrue(order != null,"该用户已抢到该代金券，无需再抢");
 
//扣库存，采用 redis,redis 没有设置自减，所以要自减，将步长设置为-1
long count = redisTemplate.opsForHash().increment(key,"amount",-1);
AssertUtil.isTrue(count < 0,"该券已经卖完了");
 
// 下单存储到数据库
VoucherOrders voucherOrders = new VoucherOrders();
voucherOrders.setFkDinerId(dinerInfo.getId());
// Redis 中不需要维护外键信息
//voucherOrders.setFkSeckillId(seckillVouchers.getId());
voucherOrders.setFkVoucherId(seckillVouchers.getFkVoucherId());
String orderNo = IdUtil.getSnowflake(1, 1).nextIdStr();
voucherOrders.setOrderNo(orderNo);
voucherOrders.setOrderType(1);
voucherOrders.setStatus(0);
count = voucherOrdersMapper.save(voucherOrders);
AssertUtil.isTrue(count == 0,"用户抢购失败");
return ResultInfoUtil.buildSuccess(path,"抢购成功");
}
} 

{
"fkVoucherId":1,
"amount":100,
"startTime":"2020-02-04 11:12:00",
"endTime":"2021-02-06 11:12:00"
}

if (redis.call(‘hexists’, KEYS[1], KEYS[2])== 1) then
local stock = tonumber(redis.call(‘hget’, KEYS[1], KEYS[2]));
if (stock > 0) then
redis.call(‘hincrby’, KEYS[1], KEYS[2],-1);
return stock;
end;
return 0;
end;

@Bean
public DefaultRedisScript<Long> stockScript() {
  DefaultRedisScript<Long> redisScript = new DefaultRedisScript<>();
  //放在和 application.yml 同层目录下
  redisScript.setLocation(new ClassPathResource("stock.lua"));
  redisScript.setResultType(Long.class);
  return redisScript;
} 

@Transactional(rollbackFor = Exception.class)
public ResultInfo doSeckill(Integer voucherId, String accessToken, String path)
{
// 基本参数校验
AssertUtil.isTrue(voucherId == null || voucherId < 0,"请选择需要抢购的代金券");
AssertUtil.isNotEmpty(accessToken,"请登录");
// 采用 Redis
String key= RedisKeyConstant.seckill_vouchers.getKey() + voucherId;
//根据 key 获取 map
Map<String, Object> map= redisTemplate.opsForHash().entries(key);
//map 转对象
SeckillVouchers seckillVouchers = BeanUtil.mapToBean(map,SeckillVouchers.class, true, null);
// 判断是否开始、结束
Date now = new Date();AssertUtil.isTrue(now.before(seckillVouchers.getStartTime()),"该抢购还未开始");
AssertUtil.isTrue(now.after(seckillVouchers.getEndTime()),"该抢购已结束");
// 判断是否卖完
AssertUtil.isTrue(seckillVouchers.getAmount() < 1,"该券已经卖完了");
// 获取登录用户信息
String url = oauthServerName +"user/me?access_token={accessToken}";
ResultInfo resultInfo = restTemplate.getForObject(url, ResultInfo.class,
accessToken);
if (resultInfo.getCode() != ApiConstant.SUCCESS_CODE) {
resultInfo.setPath(path);
return resultInfo;
}
// 这里的 data 是一个 LinkedHashMap，SignInDinerInfo
SignInDinerInfo dinerInfo = BeanUtil.fillBeanWithMap((LinkedHashMap)
resultInfo.getData(), new SignInDinerInfo(), false);
// 判断登录用户是否已抢到(一个用户针对这次活动只能买一次)
VoucherOrders order =voucherOrdersMapper.findDinerOrder(dinerInfo.getId(),
seckillVouchers.getFkVoucherId());
AssertUtil.isTrue(order != null,"该用户已抢到该代金券，无需再抢");
 
//扣库存，采用 redis,redis 没有设置自减，所以要自减，将步长设置为-1
// long count = redisTemplate.opsForHash().increment(key,"amount",-1);
// AssertUtil.isTrue(count < 0,"该券已经卖完了");
// 下单存储到数据库
VoucherOrders voucherOrders = new VoucherOrders();
voucherOrders.setFkDinerId(dinerInfo.getId());
// Redis 中不需要维护外键信息
//voucherOrders.setFkSeckillId(seckillVouchers.getId());
voucherOrders.setFkVoucherId(seckillVouchers.getFkVoucherId());
String orderNo = IdUtil.getSnowflake(1, 1).nextIdStr();
voucherOrders.setOrderNo(orderNo);
voucherOrders.setOrderType(1);
voucherOrders.setStatus(0);
long count = voucherOrdersMapper.save(voucherOrders);
AssertUtil.isTrue(count == 0,"用户抢购失败");
// 采用 Redis + Lua 解决问题
// 扣库存
List<String> keys = new ArrayList<>();
//将 redis 的 key 放进去keys.add(key);
keys.add("amount");
Long amount =(Long) redisTemplate.execute(defaultRedisScript, keys);
AssertUtil.isTrue(amount == null || amount < 1,"该券已经卖完了");
return ResultInfoUtil.buildSuccess(path,"抢购成功");
}