springboot +rabbitmq+redis实现秒杀示例

2024-04-02 19:55

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实现说明

这里的核心在于如何在大并发的情况下保证数据库能扛得住压力，因为大并发的瓶颈在于数据库。如果用户的请求直接从前端传到数据库，显然，数据库是无法承受几十万上百万甚至上千万的并发量的。因此，我们能做的只能是减少对数据库的访问。例如，前端发出了100万个请求，通过我们的处理，最终只有10个会访问数据库，这样就会大大提升系统性能。再针对秒杀这种场景，因为秒杀商品的数量是有限的，因此采用上述实现方案。

假如，某个商品可秒杀的数量是10，那么在秒杀活动开始之前，把商品的ID和数量加载到Redis缓存。当服务端收到请求时，首先预减Redis中的数量，如果数量减到小于0时，那么随后的访问直接返回秒杀失败的信息。也就是说，最终只有10个请求会去访问数据库。

如果商品数量比较多，比如1万件商品参与秒杀，那么就有1万*10=10万个请求并发去访问数据库，数据库的压力还是会很大。这里就用到了另外一个非常重要的组件：消息队列。我们不是把请求直接去访问数据库，而是先把请求写到消息队列中，做一个缓存，然后再去慢慢的更新数据库。这样做之后，前端用户的请求可能不会立即得到响应是成功还是失败，很可能得到的是一个排队中的返回值，这个时候，需要客户端去服务端轮询，因为我们不能保证一定就秒杀成功了。当服务端出队，生成订单以后，把用户ID和商品ID写到缓存中，来应对客户端的轮询就可以了。这样处理以后，我们的应用是可以很简单的进行分布式横向扩展的，以应对更大的并发。当然，秒杀系统还有很多要处理的事情，比如限流防刷、分布式Session等等。

1、工具准备

rabbitmq安装：https://www.jb51.net/article/253706.htm

界面地址：http://localhost:15672/#/
用户名 guest
密码 guest

redis安装：https://www.jb51.net/article/145704.htm
jmeter安装：https://www.jb51.net/article/232152.htm

2、数据表

商品表

-- ----------------------------
-- Table structure for stock
-- ----------------------------
DROP TABLE IF EXISTS `stock`;
CREATE TABLE `stock` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) NOT NULL DEFAULT '' COMMENT '名称',
  `count` int(11) NOT NULL COMMENT '库存',
  `sale` int(11) NOT NULL COMMENT '已售',
  `version` int(11) NOT NULL COMMENT '乐观锁，版本号',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

订单表

-- ----------------------------
-- Table structure for stock_order
-- ----------------------------
DROP TABLE IF EXISTS `stock_order`;
CREATE TABLE `stock_order` (
  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,
  `sid` int(11) NOT NULL COMMENT '库存ID',
  `name` varchar(30) NOT NULL DEFAULT '' COMMENT '商品名称',
  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '创建时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

3、pom

<dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-amqp</artifactId>
 </dependency>

 <dependency>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-data-redis</artifactId>
 </dependency>

4、代码结构

5、配置config

mq配置

package com.yy.msserver.config;

import org.springframework.amqp.core.Binding;
import org.springframework.amqp.core.BindingBuilder;
import org.springframework.amqp.core.Exchange;
import org.springframework.amqp.core.ExchangeBuilder;
import org.springframework.amqp.core.Queue;
import org.springframework.amqp.support.converter.Jackson2JsonMessageConverter;
import org.springframework.amqp.support.converter.MessageConverter;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
public class MyRabbitMQConfig {

    //库存交换机
    public static final String STORY_EXCHANGE = "STORY_EXCHANGE";

    //订单交换机
    public static final String ORDER_EXCHANGE = "ORDER_EXCHANGE";

    //库存队列
    public static final String STORY_QUEUE = "STORY_QUEUE";

    //订单队列
    public static final String ORDER_QUEUE = "ORDER_QUEUE";

    //库存路由键
    public static final String STORY_ROUTING_KEY = "STORY_ROUTING_KEY";

    //订单路由键
    public static final String ORDER_ROUTING_KEY = "ORDER_ROUTING_KEY";
    @Bean
    public MessageConverter messageConverter() {
        return new Jackson2JsonMessageConverter();
    }
    //创建库存交换机
    @Bean
    public Exchange getStoryExchange() {
        return ExchangeBuilder.directExchange(STORY_EXCHANGE).durable(true).build();
    }
    //创建库存队列
    @Bean
    public Queue getStoryQueue() {
        return new Queue(STORY_QUEUE);
    }
    //库存交换机和库存队列绑定
    @Bean
    public Binding bindStory() {
        return BindingBuilder.bind(getStoryQueue()).to(getStoryExchange()).with(STORY_ROUTING_KEY).noargs();
    }
    //创建订单队列
    @Bean
    public Queue getOrderQueue() {
        return new Queue(ORDER_QUEUE);
    }
    //创建订单交换机
    @Bean
    public Exchange getOrderExchange() {
        return ExchangeBuilder.directExchange(ORDER_EXCHANGE).durable(true).build();
    }
    //订单队列与订单交换机进行绑定
    @Bean
    public Binding bindOrder() {
        return BindingBuilder.bind(getOrderQueue()).to(getOrderExchange()).with(ORDER_ROUTING_KEY).noargs();
    }
}

redis配置

package com.yy.msserver.config;


import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.serializer.GenericJackson2JsonRedisSerializer;
import org.springframework.data.redis.serializer.StringRedisSerializer;

@Configuration
public class RedisConfig {
    // 配置redis得配置详解
    @Bean
    public RedisTemplate<String, Object> redisTemplate(RedisConnectionFactory redisConnectionFactory) {
        RedisTemplate<String, Object> template = new RedisTemplate<String, Object>();
        template.setConnectionFactory(redisConnectionFactory);
        template.setKeySerializer(new StringRedisSerializer());
        template.setValueSerializer(new GenericJackson2JsonRedisSerializer());
        template.setHashKeySerializer(new GenericJackson2JsonRedisSerializer());
        template.setHashValueSerializer(new GenericJackson2JsonRedisSerializer());
        template.afterPropertiesSet();
        return template;
    }
}

6、订单业务层

接口层

package com.yy.msserver.service;

import com.yy.msserver.model.vo.Stock;


public interface StockOrderService {
    public Integer createOrder(Integer id);

    public void decrByStock(Integer id);
}

实现层

package com.yy.msserver.service.impl;

import com.yy.msserver.dao.StockMapper;
import com.yy.msserver.dao.StockOrderMapper;
import com.yy.msserver.model.vo.Stock;
import com.yy.msserver.model.vo.StockOrder;
import com.yy.msserver.service.StockOrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import java.util.Date;


@Service
public class StockOrderServiceImpl implements StockOrderService {
    @Autowired
    private StockOrderMapper stockOrderMapper;

    @Autowired
    private StockMapper stockMapper;

    @Override
    @Transactional(rollbackFor = Exception.class)
    public Integer createOrder(Integer id) {
        //校验库存
        Stock stock = checkStock(id);
//        if(stock.getCount()>0){
//            System.out.println("当前库存：" + stock.getCount());
//            //扣库存
//            if(updateSale(stock) == 1){
//
//            }else {
//                return 0;
//            }
//        }
//        return 0;
        return createOrder(stock);
    }

    @Override
    public void decrByStock(Integer id){
        //校验库存
        Stock stock = checkStock(id);
        if(stock.getCount()>0){
            System.out.println("当前库存：" + stock.getCount());
            //扣库存
            updateSale(stock);
        }
    }

    //校验库存
    private Stock checkStock(Integer id) {
        return stockMapper.checkStock(id);
    }

    //扣库存
    private int updateSale(Stock stock){
        return stockMapper.updateSale(stock);
    }

    //下订单
    private Integer createOrder(Stock stock){
        StockOrder order = new StockOrder();
        order.setSid(stock.getId());
        order.setCreateTime(new Date());
        order.setName(stock.getName());
        stockOrderMapper.createOrder(order);
        return order.getId();
    }
}

7、redis实现层

package com.yy.msserver.service;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Service;
import java.util.Date;
import java.util.concurrent.TimeUnit;


@Service
public class RedisService {
    @Autowired
    private RedisTemplate<String, Object> redisTemplate;
    
    public void put(String key, Object value, long millis) {
        redisTemplate.opsForValue().set(key, value, millis, TimeUnit.MINUTES);
    }
    public void putForHash(String objectKey, String hkey, String value) {
        redisTemplate.opsForHash().put(objectKey, hkey, value);
    }
    public <T> T get(String key, Class<T> type) {
        return (T) redisTemplate.boundValueOps(key).get();
    }
    public void remove(String key) {
        redisTemplate.delete(key);
    }
    public boolean expire(String key, long millis) {
        return redisTemplate.expire(key, millis, TimeUnit.MILLISECONDS);
    }
    public boolean persist(String key) {
        return redisTemplate.hasKey(key);
    }
    public String getString(String key) {
        return (String) redisTemplate.opsForValue().get(key);
    }
    public Integer getInteger(String key) {
        return (Integer) redisTemplate.opsForValue().get(key);
    }
    public Long getLong(String key) {
        return (Long) redisTemplate.opsForValue().get(key);
    }
    public Date getDate(String key) {
        return (Date) redisTemplate.opsForValue().get(key);
    }

    
    public Long decrBy(String key) {
        return redisTemplate.opsForValue().decrement(key);
    }
}

8、mq实现层

减库存

package com.yy.msserver.service;

import com.yy.msserver.config.MyRabbitMQConfig;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Slf4j
@Service
public class MQStockService {
    @Autowired
    private StockOrderService stockService;
    
    @RabbitListener(queues = MyRabbitMQConfig.STORY_QUEUE)
    public void decrByStock(Integer id) {
        
        log.info("减库存");
        stockService.decrByStock(id);
    }
}

下订单

package com.yy.msserver.service;

import com.yy.msserver.config.MyRabbitMQConfig;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Service
@Slf4j
public class MQOrderService {
    @Autowired
    private StockOrderService orderService;
    
    @RabbitListener(queues = MyRabbitMQConfig.ORDER_QUEUE)
    public void createOrder(Integer id) {
        log.info("收到订单消息");
        orderService.createOrder(id);
    }
}

9、redis模拟初始化库存量

package com.yy.msserver.config;

import com.yy.msserver.service.RedisService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;


@Component
public class InitConfig {
    @Autowired
    private RedisService redisService;
    
    @PostConstruct
    public void init() {
        redisService.put("1", 10, 20);
    }
}

10、controller控制层

 
    @GetMapping( value = "/sec",produces = "application/json;charset=utf-8")
    @ResponseBody
    public String sec(@RequestParam(value = "id") int id) {

        String message = null;
        //调用redis给相应商品库存量减一
        Long decrByResult = redisService.decrBy(id+"");
        if (decrByResult >= 0) {
            
            //发消息给库存消息队列，将库存数据减一
            rabbitTemplate.convertAndSend(MyRabbitMQConfig.STORY_EXCHANGE, MyRabbitMQConfig.STORY_ROUTING_KEY, id);

            //发消息给订单消息队列，创建订单
            rabbitTemplate.convertAndSend(MyRabbitMQConfig.ORDER_EXCHANGE, MyRabbitMQConfig.ORDER_ROUTING_KEY, id);
            message = "商品" + id + "秒杀成功";
        } else {
            
            message ="商品" + id + "秒杀商品的库存量没有剩余,秒杀结束";
        }
        return message;
    }