实现基于SpringBoot+Maven+Mysql+Redis+RabbitMQ 的高并发秒杀系统(限时秒杀)

原理：

秒杀与其他业务最大的区别在于，在秒杀的瞬间，系统的并发量和吞吐量会非常大，与此同时，网络的流量也会瞬间变大。

对于网络流量瞬间变大问题，最常用的办法就是将页面静态化，也就是我们常说的前后端分离。把静态页面直接缓存到用户的浏览器中，当用户需要获取数据时，就从服务端接口动态获取。这样会大大节省网络的流量，如果再加上CDN优化，一般都不会有大问题。

对于系统并发量变大问题，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，因此这种做法刚好适用。

那么具体是如何来减少对数据库的访问的呢？

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.搭建项目环境

下方提供了安装工具的博客

1.1 安装RabbitMQ

https://blog.csdn.net/m0_37034294/article/details/82839494

2.2 安装Redis+RedisDesktopManager

https://blog.csdn.net/qq_39135287/article/details/82686837

2.3 Jmeter压力测试工具

https://blog.csdn.net/liuyanh2006/article/details/82494548

2.4 创建数据库表结构

注意：请将主键设为自动增长

2.项目代码

1.创建一个springboot项目，启动器可先不选择，下方直接放pom.xml文件，cv即可。

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-jpa</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <scope>runtime</scope>
        <optional>true</optional>
    </dependency>
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.commons</groupId>
        <artifactId>commons-lang3</artifactId>
        <version>3.8.1</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-amqp</artifactId>
    </dependency>
    <dependency>
        <groupId>io.jsonwebtoken</groupId>
        <artifactId>jjwt</artifactId>
        <version>0.7.0</version>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-data-redis</artifactId>
    </dependency>
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>2.1.0</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-tx</artifactId>
    </dependency>
    <dependency>
        <groupId>tk.mybatis</groupId>
        <artifactId>mapper-spring-boot-starter</artifactId>
        <version>2.0.3-beta1</version>
    </dependency>
    <dependency>
        <groupId>tk.mybatis</groupId>
        <artifactId>mapper</artifactId>
        <version>4.0.0</version>
    </dependency>

2.配置application.properties文件

spring.devtools.restart.enabled=false
##配置数据库连接
spring.datasource.username=root
spring.datasource.password=root
server.port=8443
spring.datasource.url=jdbc:mysql://localhost:3306/myredis?useUnicode=true&characterEncoding=UTF-8&serverTimezone=UTC&allowMultiQueries=true
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver

##配置rabbitmq连接
spring.rabbitmq.host=localhost
spring.rabbitmq.port=5672
spring.rabbitmq.username=guest
spring.rabbitmq.password=guest

#JPA Configuration:
spring.jpa.database-platform=org.hibernate.dialect.MySQLDialect

##配置连接redis --都记得打开服务
spring.redis.host=localhost
spring.redis.port=6379 
spring.redis.jedis.pool.max-active=1024
spring.redis.jedis.pool.max-wait=-1s
spring.redis.jedis.pool.max-idle=200
spring.redis.password=123456

3. 新建pojo包，添加实体类

   本次数据库操作方面使用了tkmybatis框架，所以实体类我们需要用到JPA的注解，来实现映射关系。

   
   import java.io.Serializable;
   import lombok.Data;
   import javax.persistence.Column;
   import javax.persistence.GeneratedValue;
   import javax.persistence.GenerationType;
   import javax.persistence.Id;
   import javax.persistence.Table;
   @Data
   @Table(name = "t_order")
   public class Order implements Serializable {
       private static final long serialVersionUID = -8867272732777764701L;
   
       @Id
       @Column(name = "id")
       @GeneratedValue(strategy = GenerationType.IDENTITY)
       private Long id;
   
       @Column(name = "order_name")
       private String order_name;
   
       @Column(name = "order_user")
       private String order_user;
   }
   

   
   import lombok.Data;
   import javax.persistence.Column;
   import javax.persistence.GeneratedValue;
   import javax.persistence.GenerationType;
   import javax.persistence.Id;
   import javax.persistence.Table;
   import java.io.Serializable;
   @Table(name = "stock")
   @Data
   public class Stock implements Serializable {
       private static final long serialVersionUID = 2451194410162873075L;
   
       @Id
       @Column(name = "id")
       @GeneratedValue(strategy = GenerationType.IDENTITY)
       private Long id;
   
       @Column(name = "name")
       private String name;
   
       @Column(name = "stock")
       private Long stock;
   }
   

4. 配置tkmybatis的接口

​ 4.1 需要通过继承它来实现数据库操作

4. 2新建名为base的包，在base下面新建service的接口

5. 3新建GenericMapper接口

import tk.mybatis.mapper.common.Mapper;
import tk.mybatis.mapper.common.MySqlMapper;

public interface GenericMapper<T> extends Mapper<T>, MySqlMapper<T> {
}

5. 新建mapper层

OrderMapper.java

import com.demo.base.service.GenericMapper;
import com.demo.pojo.Order;

public interface OrderMapper extends GenericMapper<Order> {
    void insertOrder(Order order);
}
    

StockMapper.java

import com.demo.base.service.GenericMapper;
import com.demo.pojo.Stock;

public interface StockMapper extends GenericMapper<Stock> {
}

6. 编写RabbitMQ和redis的配置类
   新建config包，新建redis和RabbitMQ的类

package com.demo.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();
    }
}

package com.demo.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;
    }
}

7. 编写service层
   新建service包以及impl包，这里只提供实现类

import com.demo.mapper.OrderMapper;
import com.demo.pojo.Order;
import com.demo.service.OrderService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class OrderServiceImpl implements OrderService {
    @Autowired
    private OrderMapper orderMapper;
    @Override
    public void createOrder(Order order) {
        orderMapper.insert(order);
    }
}

package com.demo.service.impl;
import com.demo.mapper.StockMapper;
import com.demo.pojo.Stock;
import com.demo.service.StockService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.util.CollectionUtils;
import tk.mybatis.mapper.entity.Example;
import java.util.List;
@Service
public class StockServiceImpl implements StockService {
    @Autowired
    private StockMapper stockMapper;
    // 秒杀商品后减少库存
    @Override
    public void decrByStock(String stockName) {
        Example example = new Example(Stock.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("name", stockName);
        List<Stock> stocks = stockMapper.selectByExample(example);
        if (!CollectionUtils.isEmpty(stocks)) {
            Stock stock = stocks.get(0);
            stock.setStock(stock.getStock() - 1);
            stockMapper.updateByPrimaryKey(stock);
        }
    }
    // 秒杀商品前判断是否有库存
    @Override
    public Integer selectByExample(String stockName) {
        Example example = new Example(Stock.class);
        Example.Criteria criteria = example.createCriteria();
        criteria.andEqualTo("name", stockName);
        List<Stock> stocks = stockMapper.selectByExample(example);
        if (!CollectionUtils.isEmpty(stocks)) {
            return stocks.get(0).getStock().intValue();
        }
        return 0;
    }
}

8. 继续在 service包下面新建

   MQOrderService.java

package com.demo.service;

import com.demo.config.MyRabbitMQConfig;
import com.demo.pojo.Order;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.annotation.RabbitListener;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
/*订单的消费队列*/
@Service
@Slf4j
public class MQOrderService {
    @Autowired
    private OrderService orderService;
    /**
     * 监听订单消息队列，并消费
     *
     * @param order
     */
    @RabbitListener(queues = MyRabbitMQConfig.ORDER_QUEUE)
    public void createOrder(Order order) {
        log.info("收到订单消息，订单用户为：{}，商品名称为：{}", order.getOrder_user(), order.getOrder_name());
        /**
         * 调用数据库orderService创建订单信息
         */
        orderService.createOrder(order);
    }
}

MQStockService.java

package com.demo.service;

import com.demo.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;
/*消费队列*/
@Service
@Slf4j
public class MQStockService {
    @Autowired
    private StockService stockService;
    /**
     * 监听库存消息队列，并消费
     * @param stockName
     */
    @RabbitListener(queues = MyRabbitMQConfig.STORY_QUEUE)
    public void decrByStock(String stockName) {
        log.info("库存消息队列收到的消息商品信息是：{}", stockName);
        /**
         * 调用数据库service给数据库对应商品库存减一
         */
        stockService.decrByStock(stockName);
    }
}

RedisService.java

**主要用来实现对redis得key和value初始化以及对value得操作** 

package com.demo.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;
    /**
     * 设置String键值对
     * @param key
     * @param value
     * @param millis
     */
    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);
    }

    /**
     * 对指定key的键值减一
     * @param key
     * @return
     */
    public Long decrBy(String key) {
        return redisTemplate.opsForValue().decrement(key);
    }
}

​ 下面为service包得完整目录

10. 新建controller层,添加SecController.java,包含两种方法，参考下面的代码

```java
import com.demo.config.MyRabbitMQConfig;
import com.demo.pojo.Order;
import com.demo.service.OrderService;
import com.demo.service.RedisService;
import com.demo.service.StockService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.amqp.rabbit.core.RabbitTemplate;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
@Controller
@Slf4j
public class SecController {
    @Autowired
    private RabbitTemplate rabbitTemplate;
    @Autowired
    private RedisService redisService;
    @Autowired
    private OrderService orderService;
    @Autowired
    private StockService stockService;
    /**
     * 使用redis+消息队列进行秒杀实现
     *
     * @param username
     * @param stockName
     * @return
     */
    @PostMapping( value = "/sec",produces = "application/json;charset=utf-8")
    @ResponseBody
    public String sec(@RequestParam(value = "username") String username, @RequestParam(value = "stockName") String stockName) {

        log.info("参加秒杀的用户是：{}，秒杀的商品是：{}", username, stockName);
        String message = null;
        //调用redis给相应商品库存量减一
        Long decrByResult = redisService.decrBy(stockName);
        if (decrByResult >= 0) {
            /**
             * 说明该商品的库存量有剩余，可以进行下订单操作
             */
            log.info("用户：{}秒杀该商品：{}库存有余，可以进行下订单操作", username, stockName);
            //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, stockName);

            //发消息给订单消息队列，创建订单
            Order order = new Order();
            order.setOrder_name(stockName);
            order.setOrder_user(username);
            rabbitTemplate.convertAndSend(MyRabbitMQConfig.ORDER_EXCHANGE, MyRabbitMQConfig.ORDER_ROUTING_KEY, order);
            message = "用户" + username + "秒杀" + stockName + "成功";
        } else {
            /**
             * 说明该商品的库存量没有剩余，直接返回秒杀失败的消息给用户
             */
            log.info("用户：{}秒杀时商品的库存量没有剩余,秒杀结束", username);
            message = "用户："+ username + "商品的库存量没有剩余,秒杀结束";
        }
        return message;
    }

    /**
     * 实现纯数据库操作实现秒杀操作
     * @param username
     * @param stockName
     * @return
     */
    @RequestMapping("/secDataBase")
    @ResponseBody
    public String secDataBase(@RequestParam(value = "username") String username, @RequestParam(value = "stockName") String stockName) {
        log.info("参加秒杀的用户是：{}，秒杀的商品是：{}", username, stockName);
        String message = null;
        //查找该商品库存
        Integer stockCount = stockService.selectByExample(stockName);
        log.info("用户：{}参加秒杀，当前商品库存量是：{}", username, stockCount);
        if (stockCount > 0) {
            /**
             * 还有库存，可以进行继续秒杀，库存减一,下订单
             */
            //1、库存减一
            stockService.decrByStock(stockName);
            //2、下订单
            Order order = new Order();
            order.setOrder_user(username);
            order.setOrder_name(stockName);
            orderService.createOrder(order);
            log.info("用户：{}.参加秒杀结果是：成功", username);
            message = username + "参加秒杀结果是：成功";
        } else {
            log.info("用户：{}.参加秒杀结果是：秒杀已经结束", username);
            message = username + "参加秒杀活动结果是：秒杀已经结束";
        }
        return message;
    }

}
```

11. 编写springboot启动类，对redis进行初始化，**简而言之就是调用我们上面写得方法，新建一个redis缓存，模拟商品信息** 

    ```java
    import com.demo.service.RedisService;
    import org.springframework.boot.SpringApplication;
    import org.springframework.boot.autoconfigure.SpringBootApplication;
    
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.boot.ApplicationArguments;
    import org.springframework.boot.ApplicationRunner;
    import tk.mybatis.spring.annotation.MapperScan;
    @MapperScan("com.demo.mapper")
    @SpringBootApplication
    public class DemoApplication  implements ApplicationRunner{
    
        public static void main(String[] args) {
            SpringApplication.run(DemoApplication.class, args);
        }
        @Autowired
        private RedisService redisService;
        /**
         * redis初始化商品的库存量和信息
         * @param args
         * @throws Exception
         */
        @Override
        public void run(ApplicationArguments args) throws Exception {
            redisService.put("watch", 10, 20);
        }
    }
    ```

    12. 至此，代码已全部写完，下图为项目目录，下面进入测试步骤，请检查以上步骤是否出错！

        [外链图片转存失败,源站可能有防盗链机制,建议将图片保存下来直接上传(img-T5smGH7i-1577175164825)(C:\Users\WuLian\Pictures\1\QQ图片20191224144222.png)]

3.测试项目

1. 启动springboot项目，并且打开 redis和rabbitmq的服务

2. 打开Redis Desktop Manager工具，查看是否新建了一个redis ：watch

3. 打开我们得JMeter工具

3.1 选择中文

3.2 完成中文之后，我们在测试计划右键，添加一个线程组

3.3 给这个线程组得数量为40，这个线程组得作用就是模拟40个用户发送请求，去秒杀.然后再在线程组右键，添加一个Http请求，这个就是我们用来发送请求得组件了 

3.4 这个请求唯一要说得就是，随机参数了，因为用户名肯定不可能给40个相同得名字，**这边我们利用JMeter给用户名得值为随机数**

点击上方得白色小书本，选择random，1-99得随机数

3.5 然后我们把这个函数字符串复制到http得参数上面去

3.6 最后我们在测试计划建一个结果树，查看我们发送请求返回得消息数据

3.7 点击运行

4.测试结果

直接在run控制台查看运行结果，以及数据库表的变化。