CREATE TABLE `t_red_envelope` (
 `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'ID',
 `amount` decimal(10,2) DEFAULT NULL COMMENT '金额',
 `num` int(11) DEFAULT NULL COMMENT '数量(分割成几分)',
 `create_time` datetime DEFAULT NULL COMMENT '创建时间',
 `update_time` datetime DEFAULT NULL COMMENT '更新时间',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb4 COMMENT='红包'

CREATE TABLE `t_red_envelope_record` (
 `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'id',
 `user_id` bigint(20) DEFAULT NULL COMMENT '用户id',
 `reward` decimal(10,2) DEFAULT NULL COMMENT '领取到奖励',
 `red_envelope_id` bigint(20) DEFAULT NULL COMMENT '红包id',
 `create_time` datetime DEFAULT NULL COMMENT '创建时间',
 `update_time` datetime DEFAULT NULL COMMENT '更新时间',
 PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=11 DEFAULT CHARSET=utf8mb4 COMMENT='红包领取记录'

 public Long divideRedEnvelope(int amount, int num) {
  /**
   * 每个人至少分到一分钱,如果有2000分，6人，随机得到五个小于1994（2000-6）的数
   * 比如 a1=4，a2=120，a3=324，a4=500，a5=700(随机拿到的五个数进行排序)，那么红包钱分别为： a1+1,a2-a1+1,a3-a2+1,a4-a3+1,a5-a4+1,1994-a5+1(总和刚好为2000)
   */
  RedEnvelope redEnvelope = new RedEnvelope();
  redEnvelope.setAmount(new BigDecimal(amount));
  redEnvelope.setNum(num);
  redEnvelope.setCreateTime(new Date());
  redEnvelope.setUpdateTime(new Date());
  redEnvelopeDao.insert(redEnvelope);
  /**
   * 拿来随机分的，按分来算
   */
  int totalAmount = amount * 100 - num;
  /**
   * 随机数
   */
  int[] randomNum = new int[num - 1];
  /**
   * 红包金额
   */
  int[] redEnvelopeAmount = new int[num];

  for (int i = 0; i < num - 1; i++) {
   int rand = new Random().nextInt(totalAmount);
   randomNum[i] = rand;
  }
  Arrays.sort(randomNum);
  /**
   * 条件语句分别分配的第一个、最后一个、中间的红包
   */
  for (int i = 0; i < num; i++) {
   if (i == 0) {
    redEnvelopeAmount[i] = randomNum[i] + 1;
   } else if (i == num - 1) {
    redEnvelopeAmount[i] = totalAmount - randomNum[i - 1] + 1;
   } else {
    redEnvelopeAmount[i] = randomNum[i] - randomNum[i - 1] + 1;
   }
  }
  /**
   * 产生的小红包key,以list存储在reids中
   */
  String key = "envelope:redEnvelopeId:" + redEnvelope.getId();
  Boolean flag = stringRedisTemplate.hasKey(key);
  if (!flag) {
   for (Integer i : redEnvelopeAmount) {
    stringRedisTemplate.opsForList().leftPush(key, i + "");
   }
  }
  return redEnvelope.getId();
 }

 public String grabRedEnvelope(Long userId, Long redEnvelopeId) {

  DefaultRedisScript<String> redisScript = new DefaultRedisScript<>();
  redisScript.setResultType(String.class);
  redisScript.setScriptText(LuaScript.redLua);
  List<String> keyList = new ArrayList();
  /**
   * 产生的小红包key
   */
  keyList.add("envelope:redEnvelopeId:" + redEnvelopeId);
  /**
   * 红包领取记录key
   */
  keyList.add("envelope:record:" + redEnvelopeId);
  keyList.add("" + userId);
  keyList.add(String.valueOf(userId));
  /**
   * -1 已经抢到红包 -2 红包已经完了 ，其余是抢到红包并返回红包余额
   */
  String result = stringRedisTemplate.execute(redisScript, keyList);
  return result;
 }

public class LuaScript {

 /**
  * -1 已经抢到红包 -2 红包被抢光 re 红包金额 ，keys[1]、keys[2]、keys[3]分别为存储小红包的key、红包领取记录key、用户id
  */
 public static String redLua = "if redis.call('hexists',KEYS[2],KEYS[3]) ~=0 then \n" +
   " return '-1';\n" +
   " else \n" +
   "local re=redis.call('rpop',KEYS[1]);\n" +
   "if re then\n" +
   "redis.call('hset',KEYS[2],KEYS[3],1);\n" +
   "return re;\n" +
   "else\n" +
   "return '-2';\n" +
   "end\n" +
   "end";
}