Kafaka+Redis异步实现商品下单减库存【SpringCloud系列18】

末蓝、 2023-10-09 17:43 20阅读 0赞

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本文章是系列文章中的一篇

*  [1、SpringCloud 项目基础工程搭建 【SpringCloud系列1】][1_SpringCloud _ _SpringCloud_1]
 *  [2、SpringCloud 集成Nacos注册中心 【SpringCloud系列2】][2_SpringCloud _Nacos_ _SpringCloud_2]
 *  [3、SpringCloud Feign远程调用 【SpringCloud系列3】][3_SpringCloud Feign_ _SpringCloud_3]
 *  [4、SpringCloud Feign远程调用公共类抽取 【SpringCloud系列4】][4_SpringCloud Feign_ _SpringCloud_4]
 *  [5、SpringCloud 整合Gateway服务网关 【SpringCloud系列5】][5_SpringCloud _Gateway_ _SpringCloud_5]
 *  [6、SpringCloud 整合 Spring Security 认证鉴权【SpringCloud系列6】][6_SpringCloud _ Spring Security _SpringCloud_6]
 *  [SpringCloud网关Gateway认证鉴权【SpringCloud系列7】][SpringCloud_Gateway_SpringCloud_7]
 *  [SpringCloud Gateway 通过redis实现限流【SpringCloud系列8】][SpringCloud Gateway _redis_SpringCloud_8]
 *  [SpringCloud Gateway 整合阿里 Sentinel网关流控、熔断、降级【SpringCloud系列9】][SpringCloud Gateway _ Sentinel_SpringCloud_9]
 *  [SpringCloud Gateway 整合RSA对请求参数解密、响应结果加密【SpringCloud系列10】][SpringCloud Gateway _RSA_SpringCloud_10]
 *  [SpringCloud 业务管理后台 通过FeignClient来调用oauth/token接口【SpringCloud系列11】][SpringCloud _ _FeignClient_oauth_token_SpringCloud_11]
 *  [Spring Security OAuth2.0 多点登录与单点登录【SpringCloud系列12】][Spring Security OAuth2.0 _SpringCloud_12]
 *  [SpringCloud 微信小程序登录 方案一【SpringCloud系列13】][SpringCloud _ _SpringCloud_13]
 *  [SpringCloud 微信小程序 获取手机号一键登录 【SpringCloud系列14】][SpringCloud _ _ _SpringCloud_14]
 *  [SpringCloud 微信小程序 获取用户信息一键登录 【SpringCloud系列15】][SpringCloud _ _ _SpringCloud_15]
 *  [SpringCloud 网关实现线程池异步批量保存请求日志 【SpringCloud系列16】][SpringCloud _ _SpringCloud_16]
 *  [乐观锁+Redis缓存实现商品下单减库存【SpringCloud系列17】][Redis_SpringCloud_17]

--------------------

首先我这里的服务体系是：（网关认证这些不在此图中）

![在这里插入图片描述][0fa66d2af0b94e279b48bff640280f55.png]

##### 1 前端循环查询订单详情接口 #####

异步下单，前端APP或者小程序调用下单接口，生成订单号  
![在这里插入图片描述][c710067eac514aa29b9bb1c7d00a3b59.png]

然后前端使用这个订单号，跳转到订单详情页面 轮循这个订单详情接口，下单成功显示订单详情。  
![在这里插入图片描述][9994285e7eca44a49137348276b9a31a.png]  
轮循订单详情接口，下单失败，显示错误弹框，然后点击确认退出页面。  
![在这里插入图片描述][9022414ec74f44b880ee5660bab8dc88.png]  
小程序的下单流程如下

![在这里插入图片描述][d8f10f20863d4b108a6c4e2c783f860d.png]  
那首先是根据 sn 来查询订单详情

*  查询 Redis 中是否有订单号标识
 *  查询 对应订单号是否下单成功
 *  根据订单号 查询 Redis 缓存中的订单详情

@Service
    @Slf4j
    public class OrderServiceImpl implements OrderService {
        
        @Autowired
        private RedisService redisService;
        @Override
        public OrderInfo getOrderInfoBySn(String sn) {
        
            Boolean aBoolean = redisService.hasKey(Constant.ORDER_SN + sn);
            if (!aBoolean) {
        
                throw new RuntimeException("下单失败 库存不足");
            }
            //1正在处理中
            int statues = Integer.parseInt(redisService.get(Constant.ORDER_SN + sn).toString());
            if (statues == 1) {
        
                return null;
            }
            if (statues == 3) {
        
                throw new RuntimeException("下单失败 库存不足");
            }
            //缓存订单信息
            OrderInfo orderInfo = (OrderInfo) redisService.get(Constant.ORDER_SN_NORMAL + sn);
            return orderInfo;
        }
    }

预下单时会生成订单号，然后将订单号标识保存到Redis中，并设置有效期为1分钟，标识状态如下：

*  1 队列正在处理中
 *  2 下单成功
 *  3 下单失败

##### 2 订单预下单生成订单号 #####

我这里是在 mini-service 服务中预下单，mini-service 中要集成 kafaka

<dependency>
            <groupId>org.springframework.kafka</groupId>
            <artifactId>spring-kafka</artifactId>
        </dependency>

然后添加配置如下：

spring:
    
      kafka:
        bootstrap-servers: localhost:9092
        consumer:
          group-id: Qgchun// 设置默认的生产者消费者所属组id
        template:
          default-topic: ORDER-CREATE-TOPIC

需要注意的是，开发环境要安装kafaka ，然后在预下单的时候发送下单的消息如下：

@Service
    @Slf4j
    public class OrderServiceImpl implements OrderService {
        
        @Autowired
        private SnowFlakeCompone snowFlakeCompone;
        @Autowired
        private RedisService redisService;
        @Resource
        private KafkaTemplate<String, String> kafkaTemplate;
        @Value("${spring.kafka.template.default-topic}")
        private String kafkaTopic;
    
        @Override
        public String asyncCreatOrder(Long userId, Long goodsId) {
        
            //判断库存
            Boolean aBoolean = redisService.hasKey(Constant.GOOOD_STOCK + goodsId);
            if (!aBoolean) {
        
                throw new RuntimeException("库存不足");
            }
            //雪花算法订单号
            String nextId = snowFlakeCompone.getInstance().nextId() + "";
            //Redis保存预订单号状态 1 为正在处理中 2为下单完成 3为下单失败
            redisService.set(Constant.ORDER_SN + nextId, 1);
            //设置过期时间1分钟
            redisService.expire(Constant.ORDER_SN + nextId, 60);
    
            OrderMessage message = new OrderMessage();
            message.setSn(nextId);
            message.setUserId(userId);
            message.setGoodsId(goodsId);
            message.setNum(1);//下单商品数量
            //kafka下单消息发送
            kafkaTemplate.send(kafkaTopic, JSON.toJSONString(message));//使用send方法发送消息，需要传入topic名称
            log.info("消息发送至 Kafka 成功");
    
            return nextId;
        }
    }

##### 3 订单服务定义 kafaka 消费者 #####

创建一个消费者，使用 @KafkaListener 来监听对应的通道

@Slf4j
    @Component
    public class OrderConsumerListen {
        
    
    
        @Resource
        private OrderKafakaService orderKafakaService;
    
        @KafkaListener(topics = "ORDER-CREATE-TOPIC")
        public void listen(ConsumerRecord<String, String> record) throws Exception {
        
            Optional<?> kafkaMessage = Optional.ofNullable(record.value());
            // Object -> String
            String message = (String) kafkaMessage.get();
            // 反序列化
            OrderMessage orderMessage = JSON.parseObject(message,OrderMessage.class);
            // 创建订单
            orderKafakaService.consumerTopicToCreateOrderWithKafka(orderMessage);
        }
    }

OrderKafakaService 就是实现下单的处理：

*  校验库存，从 Redis 中获取库存信息
 *  乐观锁更新数据库库存
 *  更新Redis缓存中的库存
 *  创建订单
 *  更新Redis中订单号的 标识，并缓存订单信息

@Service
    @Slf4j
    public class OrderKafakaServiceImpl extends ServiceImpl<OrderMapper, OrderInfo> implements OrderKafakaService {
        
    
        @Resource
        private GoodsInfoService goodsInfoService;
    
        @Resource
        RedisService redisService;
    
        @Override
        @Transactional
        public void consumerTopicToCreateOrderWithKafka(OrderMessage orderMessage) throws Exception {
        
            Long goodsId = orderMessage.getGoodsId();
            Long userId = orderMessage.getUserId();
            String sn = orderMessage.getSn();
            Integer num = orderMessage.getNum();
            // 第一步 校验库存，从 Redis 中获取
            GoodsInfo goodsInfo = checkStockWithRedis(goodsId);
            if(goodsInfo==null){
        
                //更新下单标识下单失败
                redisService.set(Constant.ORDER_SN+sn,3);
                return;
            }
            // 第二步 乐观锁更新库存和Redis
            boolean update = saleStockOptimsticWithRedis(goodsInfo);
            if(!update){
        
                //更新下单标识下单失败
                redisService.set(Constant.ORDER_SN+sn,3);
                return;
            }
            //第三步 创建订单
            GoodsInfo goodsInfo1 = (GoodsInfo) redisService.get(Constant.GOODS_INFO + goodsId);
    
            OrderInfo order = new OrderInfo();
    
            order.setSn(sn);
            order.setGoodsId(goodsId);
            order.setUserId(userId);
            order.setNum(num);
            order.setPrice(goodsInfo1.getGoodsPrice().multiply(new BigDecimal(num)));
            order.setName(goodsInfo1.getGoodsName());
            order.setCreateTime(new Date());
            order.setOrderStatues(0);
            boolean res = this.save(order);
            if (!res) {
        
                //更新下单标识下单失败
                redisService.set(Constant.ORDER_SN+sn,3);
                return;
    
            }
    
            //第四步 更新预下订单标识
            redisService.set(Constant.ORDER_SN+sn,2);
            //未支付取消订单 设置过期时间30分钟
            redisService.expire(Constant.ORDER_SN+sn,60*30);
            //缓存订单信息
            redisService.set(Constant.ORDER_SN_NORMAL+sn,order);
    
            log.info("Kafka 消费 Topic 创建订单成功");
    
    
        }
    
        // Redis 中校验库存
        private GoodsInfo checkStockWithRedis(Long goodsId) throws Exception {
        
            int count = Integer.parseInt(redisService.get(Constant.GOOOD_STOCK + goodsId).toString());
            int sale = Integer.parseInt(redisService.get(Constant.GOOOD_SALE + goodsId).toString());
            int version = Integer.parseInt(redisService.get(Constant.GOOOD_VERSION + goodsId).toString());
            String goodsName = redisService.get(Constant.GOODS_NAME + goodsId).toString();
            if (count < 1) {
        
                log.info("库存不足");
                return null;
            }
            GoodsInfo stock = new GoodsInfo();
            stock.setId(goodsId);
            stock.setGoodsStock(count);
            stock.setGoodsSale(sale);
            stock.setVersion(version);
            stock.setGoodsName(goodsName);
    
            return stock;
        }
    
    
        // 更新 DB 和 Redis
        private boolean saleStockOptimsticWithRedis(GoodsInfo goodsInfo) throws Exception {
        
            boolean res = goodsInfoService.updateStockByOptimistic(goodsInfo);
            if (!res) {
        
               return false;
            }
            // 更新 Redis
            redisService.updateStockWithRedis(goodsInfo);
            return true;
        }
    
    }

最后就是源码了：  
本项目 SpringCloud 源码 [https://gitee.com/android.long/spring-cloud-biglead/tree/master/biglead-api-11-admin][https_gitee.com_android.long_spring-cloud-biglead_tree_master_biglead-api-11-admin]

本项目 管理后台web 源码[https://gitee.com/android.long/spring-cloud-biglead/tree/master/mall-admin-web-master][https_gitee.com_android.long_spring-cloud-biglead_tree_master_mall-admin-web-master]

本项目 小程序 源码[https://gitee.com/android.long/spring-cloud-biglead/tree/master/mall-app-web-master][https_gitee.com_android.long_spring-cloud-biglead_tree_master_mall-app-web-master]

如果有兴趣可以关注一下公众号 biglead ,每周都会有 java、Flutter、小程序、js 、英语相关的内容分享

[1_SpringCloud _ _SpringCloud_1]: https://biglead.blog.csdn.net/article/details/129668121
[2_SpringCloud _Nacos_ _SpringCloud_2]: https://biglead.blog.csdn.net/article/details/129672545
[3_SpringCloud Feign_ _SpringCloud_3]: https://biglead.blog.csdn.net/article/details/129674404
[4_SpringCloud Feign_ _SpringCloud_4]: https://blog.csdn.net/zl18603543572/article/details/129675612
[5_SpringCloud _Gateway_ _SpringCloud_5]: https://biglead.blog.csdn.net/article/details/129678919
[6_SpringCloud _ Spring Security _SpringCloud_6]: https://biglead.blog.csdn.net/article/details/129687071
[SpringCloud_Gateway_SpringCloud_7]: https://blog.csdn.net/zl18603543572/article/details/129699896
[SpringCloud Gateway _redis_SpringCloud_8]: https://blog.csdn.net/zl18603543572/article/details/129707395
[SpringCloud Gateway _ Sentinel_SpringCloud_9]: https://biglead.blog.csdn.net/article/details/129710023
[SpringCloud Gateway _RSA_SpringCloud_10]: https://blog.csdn.net/zl18603543572/article/details/129726501
[SpringCloud _ _FeignClient_oauth_token_SpringCloud_11]: https://biglead.blog.csdn.net/article/details/129772853
[Spring Security OAuth2.0 _SpringCloud_12]: https://biglead.blog.csdn.net/article/details/129783953
[SpringCloud _ _SpringCloud_13]: https://blog.csdn.net/zl18603543572/article/details/129864600
[SpringCloud _ _ _SpringCloud_14]: https://biglead.blog.csdn.net/article/details/129874998
[SpringCloud _ _ _SpringCloud_15]: https://blog.csdn.net/zl18603543572/article/details/129877821
[SpringCloud _ _SpringCloud_16]: https://biglead.blog.csdn.net/article/details/130113744
[Redis_SpringCloud_17]: https://blog.csdn.net/zl18603543572/article/details/130142161
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[9994285e7eca44a49137348276b9a31a.png]: https://img-blog.csdnimg.cn/9994285e7eca44a49137348276b9a31a.png
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[https_gitee.com_android.long_spring-cloud-biglead_tree_master_biglead-api-11-admin]: https://gitee.com/android.long/spring-cloud-biglead/tree/master/biglead-api-11-admin
[https_gitee.com_android.long_spring-cloud-biglead_tree_master_mall-admin-web-master]: https://gitee.com/android.long/spring-cloud-biglead/tree/master/mall-admin-web-master
[https_gitee.com_android.long_spring-cloud-biglead_tree_master_mall-app-web-master]: https://gitee.com/android.long/spring-cloud-biglead/tree/master/mall-app-web-master