以下是一个简单的Java抢优惠券代码示例，使用Redis实现分布式锁和计数器功能
public class CouponService {
private JedisPool jedisPool;
public CouponService(JedisPool jedisPool) {
this.jedisPool = jedisPool;
}
public boolean grabCoupon(String couponId, String userId, int limit) {
Jedis jedis = null;
try {
jedis = jedisPool.getResource();
String lockKey = "lock:c" + couponId;
String counterKey = "c" + couponId + ":counter";
String usersKey = "c" + couponId + ":users";
// 加锁
RedisLock lock = new RedisLock(jedisPool);
if (!lock.acquire(lockKey, 200, 5000)) {
throw new RuntimeException("获取锁失败");
}
// 检查优惠券是否已经抢完
int total = Integer.parseInt(jedis.hget(couponId, "total"));
int used = Integer.parseInt(jedis.hget(couponId, "used"));
if (used >= total) {
return false;
}
// 计数器自增
int count = jedis.incr(counterKey).intValue();
if (count > limit) {
return false;
}
// 抢购成功，记录用户信息
jedis.hincrBy(couponId, "used", 1);
jedis.sadd(usersKey, userId);
return true;
} finally {
// 释放锁
if (jedis != null) {
jedis.close();
}
}
}
}