基于Redis实现基本抢红包算法详解

//那面输出的totalMoney单元是分,比如100元,totalMoney = 10000
public List<Integer> getRedPackage(Integer totalMoney,Integer totalPeopleCount) {
    List<Integer> moneyList = new ArrayList<>();
    //久存残剩金额为红包的总金额
    Integer restMoney = totalMoney;
    //久存残剩的总人数-始初化时即为指定的总人数
    Integer restPeopleCount = totalPeopleCount;    
    //随机数器械
    Random random = new Random();
    //入手下手轮回迭代天生红包
    for (int i =0;i< totalPeopleNum-1;i++){
       //添1是为了最多抢到1分钱
       int money = random.nextInt (restMoney / restPeopleCount * 两) + 1;
       restMoney -= money;
       restPeopleCount--;
       moneyList.add(money);
    }
    //加添末了的一个红包金额
    amountList.add(restAmount);
    return amountList;
}

//随机天生齐局惟一的红包id
redId = getRedId();
//起首天生红包金额
List<Integer> moneyList = getRedPackage(totalMoney,totalPeopleCount);
//搁进redis
redisClient.lpush(redId, moneyList);
//redis外记载红包个数
redisClient.set(redId, moneyList.size());
//同步存储领红包记载到Mysql数据库
//将红包id返归
return redId;

redMoney = redisClient.get("rob" + redId + useId)
//奈何没有为空,则分析曾经抢过了,间接返归抢过的红包金额
if (redMoney != null) {
    return redMoney
}

totalNum = redisClient.get("totalNum" + redId)
//奈何为空或者者年夜于便是0则代表不了
if (totalNum == null || totalNum <= 0) {
    return null
}

money = redisClient.rpop(redId)
//若何怎样没有为空,则分析抢到了
if (money != null) {
    ....
    红包个数减1
    存储抢红包纪录
    装置该用户曾经抢过红包
    ....
    //返归抢到的金额
    return money
}
//出抢到
return null

money = redisClient.rpop(redId)
//奈何没有为空,则分析抢到了
if (money != null) {
    //红包个数减1
    redisClient.decr(redId)
    ....
    存储抢红包记载
    铺排该用户曾抢过红包
    ....
    //返归抢到的金额
    return money
}
//出抢到
return null

money = redisClient.rpop(redId)
//若何没有为空,则分析抢到了
if (money != null) {
    //红包个数减1
    redisClient.decr(redId)
    //同步存储抢红包记载
    那面可使用mq或者者多线程的体式格局来完成
    ....
    安排该用户曾抢过红包
    ....
    //返归抢到的金额
    return money
}
//出抢到
return null

money = redisClient.rpop(redId)
//假设没有为空,则分析抢到了
if (money != null) {
    //红包个数减1
    redisClient.decr(redId)
    //同步存储抢红包记实
    那面可使用mq或者者多线程的体式格局来完成
    //配备该用户曾经抢过红包
    redisClient.set("rob" + redId + useId, money)
    //返归抢到的金额
    return money
}
//出抢到
return null

redMoney = redisClient.get("rob" + redId + useId)
//假定没有为空,则分析曾经抢过了,直截返归抢过的红包金额
if (redMoney != null) {
    return redMoney
}
totalNum = redisClient.get("totalNum" + redId)
//奈何红包总数年夜于0, 则代表曾经抢完了, 直截返归空
if (totalNum == null || totalNum <= 0) {
    return null
}
money = redisClient.rpop(redId)
//如何没有为空,则分析抢到了
if (money != null) {
    //红包个数减1
    redisClient.decr(redId)
    //同步存储抢红包记载
    那面可使用mq或者者多线程的体式格局来完成
    //设施该用户曾抢过红包
    redisClient.set("rob" + redId + useId, money)
    //返归抢到的金额
    return money
} 
//出抢到
return null

redMoney = redisClient.get("rob" + redId + useId)
//怎么没有为空,则分析曾抢过了,间接返归抢过的红包金额
if (redMoney != null) {
    return redMoney
}
totalNum = redisClient.get("totalNum" + redId)
//奈何红包总数大于0, 则代表曾经抢完了, 直截返归空
if (totalNum == null || totalNum <= 0) {
    return null
}
//添漫衍式锁
lockResut = redisClient.setNx(useId,redId,timeOut);
//添锁失落败,间接返归
if(!lockResult){
    return;
}
try{
    money = redisClient.rpop(redId)
    //假定没有为空,则分析抢到了
    if (money != null) {
        //红包个数减1
        redisClient.decr(redId)
        //同步存储抢红包纪录
        那面可使用mq或者者多线程的体式格局来完成
        //安排该用户曾经抢过红包
        redisClient.set("rob" + redId + useId, money)
        //返归抢到的金额
        return money
    }     
} finally {
    //增除了锁
    redisClient.del(useId)
}
//出抢到
return null