抽奖系统的java 抽奖系统的逻辑

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mob64ca141a2a87 2023-10-08 19:09:33

文章标签 抽奖系统的java node.js javascript sql 爱奇艺 文章分类 Java 后端开发

抽奖逻辑

这段时间大概做了很多这种类似抽奖的活动！苦逼的我本来是搞前端的！但是由于一些原因换了家公司后！现在前后端都得搞！所以就写一些逻辑性很多，很多的东西

不多扯了说重点吧！

抽奖逻辑这块大概是这样的。每次抽奖都会从奖品表抽取一个送给用户，这里主要需要考虑到库存不足，和并发的可能。什么是并发呢？就是比如甲，乙两个人同时抽奖，但是商品只剩一个了，但是两个都中奖了，那么我该怎么发放奖品呢？

至于处理这个并发呢？我是通过sql实现的

UPDATE price_table  set outnumber = outnumber + 1 , gmt_modified = "${curentTime()}" 

WHERE id=${price_id} AND sumnumber > outnumber`

主要就是通过这句sql看它到底执行还是没执行，如果执行了说明那个人真的抽到奖了，如果没有执行就没有抽到奖！所以需要这句sql判断一下他到底真正的抽到奖了！这里最主要的就是后面where条件限制让他sumnumer>outnumber 奖品总数大于你出奖数量一旦出奖数量和这个总数相等那么意思库存不足，这句sql就不会执行，这时候在让用户不中奖！

具体抽奖核心代码

这个抽奖的话

通过抽奖表

[{ "sumnumber": 100, "outnumber": 13, "probability": "0.3", "name": "爱奇艺会员180天", "id": 1, "create_date": "2020-07-24T08:29:33.000Z", "update_date": "2020-07-24T11:21:01.000Z", "entity": 0 },
    { "sumnumber": 10, "outnumber": 2, "probability": "0.3", "name": "海贼王手办一套", "id": 2, "create_date": "2020-07-24T08:31:19.000Z", "update_date": "2020-07-24T08:31:19.000Z", "entity": 1 },
    { "sumnumber": 10, "outnumber": 2, "probability": "0.2", "name": "腾讯Q币20元", "id": 3, "create_date": "2020-07-24T08:33:01.000Z", "update_date": "2020-07-24T08:33:01.000Z", "entity": 0 }]

这是奖品数据这个probability字段是中这个奖品的概率这个是你设置，你想设置多大就多大

以下是核心代码为了方便大家阅读我把他从项目中单独摘了出来

let pricelist = [{ "sumnumber": 100, "outnumber": 13, "probability": "0.3", "name": "爱奇艺会员180天", "id": 1, "create_date": "2020-07-24T08:29:33.000Z", "update_date": "2020-07-24T11:21:01.000Z", "entity": 0 },
    { "sumnumber": 10, "outnumber": 2, "probability": "0.3", "name": "海贼王手办一套", "id": 2, "create_date": "2020-07-24T08:31:19.000Z", "update_date": "2020-07-24T08:31:19.000Z", "entity": 1 },
    { "sumnumber": 10, "outnumber": 2, "probability": "0.2", "name": "腾讯Q币20元", "id": 3, "create_date": "2020-07-24T08:33:01.000Z", "update_date": "2020-07-24T08:33:01.000Z", "entity": 0 }]
// 0.3
// 0.3
// 0.2
    let random = Math.random();
    let price_id = 0;
    let min = 0;
    console.log(random);

    for (let i = 0; i < pricelist.length; i++) {
        if (random > min && random < (min + Number(pricelist[i].probability))) {
            console.log('我是上限',min + Number(pricelist[i].probability));
            price_id = pricelist[i].id;
            break;
        } else {
            min = min + Number(pricelist[i].probability)
        }
    }

    console.log(price_id);

这是具体详细项目代码我想很多人看不懂因为业务不同嘛我这里做的是淘宝小程序的云函数开发写的一个后端抽奖接口

'use strict';

/**
 * @name 抽奖活动后端接口
 * @version 1.0.0
 * @author yangjie
 * @Time 2020年07月24日14:55:51
 */

const DateFormat = require('dateformat-util')

exports.main = async (ctx) => {
    const { mixNick, cloud, userNick } = ctx;
    const retObj = {};

    // 判断用户是否存在
    let user_count = await cloud.dataspace.executeSql(`SELECT * FROM user_table WHERE mixnick = "${mixNick}"`);

     //拿到用户id
     let user_id = user_count[0].id;

    //如果不存在则插入到用户表(由于时区原因插入的时候需要插入东八区时间)
    if (user_count.length == 0) {
        await cloud.dataspace.executeSql(`INSERT INTO user_table (mixnick,gmt_create,gmt_modified) VALUES ('${mixNick}','${DateFormat.format(new Date(), "yyyy-MM-dd hh:mm:ss")}','${DateFormat.format(new Date(), "yyyy-MM-dd hh:mm:ss")}')`);
    }

    //如果铭文昵称存在存入铭文昵称
    if (userNick) {
        await cloud.dataspace.executeSql(`UPDATE user_table SET nickname = "" WHERE user_id = ？`, [user_id]);
    }

    // // //通过用户id判断用户每天抽奖次数

    let pricenumber = await cloud.dataspace.executeSql(`SELECT COUNT(1) AS number FROM luckdraw_table WHERE user_id = ${user_id} AND 'gmt_create' >= "${DateFormat.format(DateFormat.getDateStart(new Date()), "yyyy-MM-dd hh:mm:ss")}"`);


    // retObj.pricenumber = pricenumber;

    // //如果用户抽奖次数小于3的话可以继续抽奖

    if (pricenumber[0].number < 3) {

        //插入用户id到抽奖表
        let priceid = await cloud.dataspace.executeSql(`INSERT INTO luckdraw_table (user_id,gmt_create,gmt_modified) 
         VALUES(${user_id},'${DateFormat.format(new Date(), "yyyy-MM-dd hh:mm:ss")}','${DateFormat.format(new Date(), "yyyy-MM-dd hh:mm:ss")}')`);

        retObj.priceid = priceid;

        //     //拿到本次抽奖的id,后面做更新
        let pricenumber = priceid.insertId

        //     // retObj.pricenumber = pricenumber;

        //查询是否中过实物奖
        let pricestage = await cloud.dataspace.executeSql(`SELECT COUNT(1) as number FROM luckdraw_table AS g LEFT JOIN price_table AS u ON g.Price_id=u.id WHERE u.entity=1 and user_id = ?`, [user_id]);

        // retObj.pricestage = pricestage;

        let select_user_winprice_sql = "SELECT * FROM price_table WHERE sumnumber>outnumber AND probability > 0 ";


        if (pricestage[0].number > 0) {
            select_user_winprice_sql += "AND entity=0 ";
        }


        // 开始抽奖

        //确定奖池

        let pricelist = await cloud.dataspace.executeSql(select_user_winprice_sql);


        let random = Math.random();
        let price_id = 0;
        let min = 0;
        retObj.random = random
        // retObj.pricelist = pricelist;
        // retObj.pricelisLength = pricelist.length;
        // retObj.pricelis1 = pricelist[0].probability

        for (let i = 0; i < pricelist.length; i++) {
            if (random >= min && random < (min + Number(pricelist[i].probability))) {
                price_id = pricelist[i].id;
                break;
            } else {
                min = min + Number(pricelist[i].probability);
            }
        }

        // retObj.price_id = price_id


        if (price_id) {
            //验证是否真正抽到奖了(更新出奖数量)
            let update_price_outnumber_sql = await cloud.dataspace.executeSql(`UPDATE price_table  set outnumber = outnumber + 1 , gmt_modified = "${curentTime()}" WHERE id=${price_id} AND sumnumber > outnumber`);

            // retObj.op = update_price_outnumber_sql.affectedRows

            //如果更新了为1即取反为false  如果没有更新为0 则取反为true
            if (!update_price_outnumber_sql.affectedRows) {
                price_id = 0
            }


        }

        //重新把抽奖表赋值
        await cloud.dataspace.executeSql(`UPDATE luckdraw_table SET price_id = ${price_id} , gmt_modified = "${curentTime()}"  WHERE id = ${pricenumber} `);

        //获取抽奖详情
        if (price_id) {
            let select_price_sql = await cloud.dataspace.executeSql(`SELECT * FROM price_table WHERE id =${price_id}`);

            retObj.ispricedata = select_price_sql
        }

        retObj.price_id = price_id


    } else {

        return await basiCode(7000, retObj);

    }
    return await basiCode(0, retObj);

};

// 返回值处理
var basiCode = async (code, data) => {
    let reobj = {
        errCode: 0,
        msg: 'ok',
        data: data
    };
    if (code) {
        reobj.data = data;
        reobj.errCode = code;
        switch (code) {
            case 7000:
                reobj.msg = '抽奖次数不足!';
                break;
            case 8000:
                reobj.data = String(data);
                reobj.msg = 'System error!';
                break;
            default:
                reobj.msg = 'other error!';
                break;
        }
    } else {
        reobj.data = data;
    }
    try {
        pool.releaseConnection(mysqlConn);
    } catch (e) {
        console.log(e);
    }

    return reobj;
};

// 获取东八区时间
var curentTime = function (time) {
    var d = time ? new Date(time) : new Date();
    var localTime = d.getTime();
    var localOffset = d.getTimezoneOffset() * 60000; //获得当地时间偏移的毫秒数
    var utc = localTime + localOffset + 3600000 * 8;
    var now = new Date(utc);

    var year = now.getFullYear(); //年
    var month = now.getMonth() + 1; //月
    var day = now.getDate(); //日
    var hh = now.getHours(); //时
    var mm = now.getMinutes(); //分
    var ss = now.getSeconds(); //秒

    var clock = year + "-";

    if (month < 10)
        clock += "0";

    clock += month + "-";

    if (day < 10)
        clock += "0";

    clock += day + " ";

    if (hh < 10)
        clock += "0";

    clock += hh + ":";

    if (mm < 10)
        clock += "0";

    clock += mm + ":";

    if (ss < 10)
        clock += "0";

    clock += ss;

    return (clock);
}

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