使用Redis中间件设计商品秒杀活动（使用Java多线程模拟高并发环境）

系统管理员 2023-02-21 09:09 101阅读 0赞

# 一、引入相关依赖 #

可以新建Spring或Maven工程，在pom文件中引入Jedis依赖：

<dependencies>
            <dependency>
                <groupId>redis.clients</groupId>
                <artifactId>jedis</artifactId>
                <version>2.9.0</version>
            </dependency>
            <dependency>
                <groupId>com.alibaba</groupId>
                <artifactId>fastjson</artifactId>
                <version>1.2.58</version>
            </dependency>
            <dependency>
                <groupId>junit</groupId>
                <artifactId>junit</artifactId>
                <version>4.12</version>
            </dependency>
        </dependencies>

# 二、核心代码 #

**SecKillDemo**

package com.redis;
    
    import java.util.List;
    import redis.clients.jedis.Jedis;
    import redis.clients.jedis.Transaction;
    
    public class SecKillDemo implements Runnable { 
        //这里需要更改成自己的Redis服务器地址
        private Jedis jedis = new Jedis("10.128.*.*", 6379);
        //顾客
        private String customerName;
        //商品
        private String key;
    
        public SecKillDemo1(String customerName, String key) { 
            this.customerName = customerName;
            this.key = key;
        }
    
        @Override
        public void run() { 
            boolean success = false;
            String data;
            int currentNum;
            while (!success) { 
            	//可重复抢购直到成功
                //通过watch实现redis的incr(原子递增操作)
                jedis.watch(key);
                data = jedis.get(key);
                //获取剩余商品数
                currentNum = Integer.parseInt(data);
                if (currentNum > 0) { 
                    //开启事务
                    Transaction transaction = jedis.multi();
                    //设置新值,如果key的值被其它连接的客户端修改，那么当前连接的exec命令将执行失败
                    //方式一 ,在事务中设置data的值为原值减1，此时transaction.exec()的返回值的第一个元素是"OK"
                    currentNum--;
                    transaction.set(key, String.valueOf(currentNum));
                 
                    //方式二,在事务中对键data对应的值做减1操作，此时transaction.exec()的返回值的第一个元素是data对应的当前值
                    //transaction.decrBy(key, Integer.valueOf(currentNum--));
                    
                    List res = transaction.exec();
                    if (res.size() == 0) { 
                    	
                        String failUserInfo = "fail---" + customerName;
                        String failMsg = failUserInfo + "，抢购失败，剩余商品数量："+ currentNum ;
                        // 将秒杀失败的用户信息存入Redis。
                        jedis.setnx(failUserInfo, failMsg);
                        System.out.println(customerName + " 抢购失败");
                    } else { 
                        success = true;
    					System.out.println(customerName + " 抢购成功,[" + key + "]剩余：" + currentNum);
    					String succUserInfo = customerName + " 抢购成功,[" + key + "]";
    					String succMsg = succUserInfo + "，抢购成功，"	+ "剩余商品数量："+currentNum;
    					System.out.println(res.get(0)+ " " + succMsg);
    					
    					// 将秒杀成功的用户信息存入Redis。
    					jedis.setnx(succUserInfo, succMsg);
                    	
                    }
                } else { 
                    System.out.println("商品售空,活动结束!");
                    System.exit(0);
                }
            }
        }
    }

# 三、单元测试 #

**SecKillDemoTest**

package com.redis;
    
    import java.util.Collections;
    import java.util.concurrent.ExecutorService;
    import java.util.concurrent.Executors;
    import org.junit.Before;
    import org.junit.Test;
    import junit.framework.TestCase;
    import junit.framework.TestSuite;
    import redis.clients.jedis.Jedis;
    
    public class SecKillDemoTest { 
        //商品名称
        private static String key = "华为P40";
        //商品数量
        private static String num = "50";
        // 模拟用户抢购最大并发数
        private static ExecutorService executorService = Executors.newFixedThreadPool(5);
        
        @Before
        public void before() { 
            Jedis jedis = new Jedis("10.128.*.*");
            //命令包括set、get、del等
            //eval代表执行Lua语言的命令
            //KEYS[1]代表传递给Lua脚本的第一个key参数，
            //ARGV[1]代表第一个非key参数
            String script = "redis.call('del',KEYS[1]);return redis.call('set',KEYS[1],ARGV[1])";
            jedis.eval(script, Collections.singletonList(key), Collections.singletonList(num));
            jedis.close();
        }
        
        @Test
        public void test() { 
        	
        }
    
        public static void main(String[] args) { 
            try{ 
                for (int i = 1; i <= 100; i++) { 
                	 executorService.submit(new SecKillDemo("顾客"+i,key));
                }
            }catch (Exception e) { 
            	e.printStackTrace();
    		}finally { 
                executorService.shutdown();
            }
        }
    }

执行步骤：  
**（1）执行junit单元测试方法，在redis中构建<key,value>数据。  
（2）执行SecKillDemoTest 中的main方法。**  
执行结果如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70]  
从redis中查看结果如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70 1]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70 2]  
**代码下载地址**  
https://gitee.com/codefarmer001/spring-redis.git

参考文章：  
[使用Redis中间件解决商品秒杀活动中出现的超卖问题（使用Java多线程模拟高并发环境）][Redis_Java]  
[redis watch命令实现秒杀][redis watch]  
[Redis常用技术-----使用Lua语言][Redis_-----_Lua]

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70]: https://img-blog.csdnimg.cn/20200629202419894.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20200629202510648.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ==,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20200629202531195.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2ppa2UxMTIzMQ==,size_16,color_FFFFFF,t_70
[Redis_Java]: https://blog.csdn.net/qq_15329947/article/details/87982966
[redis watch]: https://www.jianshu.com/p/93cd65d07b56
[Redis_-----_Lua]: https://blog.csdn.net/a_helloword/article/details/81878759