使用StringRedisTemplate实现redis分布式锁

背景：单个接口可能同时被多个用户调用，但是每个用户使用的数据都是不一样，因此需要使用分布式锁解决数据减少了没有即使减少的问题

使用的指令来自的edis的setnx命令，setnx(k,v1),setnx(k.v2),当设置值为v1后，v2的设置无效

上图中启动了两台一样的服务，大多数情况，同一时间只有一条日志打印，但是定时任务是每15秒执行一次，数据有效期15秒，所以会有同一秒不同毫秒的日志打印

　当时间设置为

1	`timed.task=0` `30,35,40` `17` `* * *`

同一秒内无法保证只执行一次

但是到了毫秒级别，不一样，实际上是不一样用户，但是定时任务部署多台服务器，这样可能存在问题

上图看到没有了在一秒内重合的日志打印，这边是调整了锁的过期时间

1 2	`该行代码保证了原子性` `Boolean setIfAbsent = stringRedisTemplate.opsForValue().setIfAbsent(lockKey,` `"001",` `25, TimeUnit.SECONDS);`

相关代码部分

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
 
    <groupId>com.redis</groupId>
    <artifactId>redis-service</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/>
    </parent>
 
    <dependencies>
        <!--tomcat容器-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-redis</artifactId>
        </dependency>
        <!--lombok依赖-->
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.16</version>
        </dependency>
 
        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-pool2</artifactId>
            <version>2.4.1</version>
        </dependency>
    </dependencies>
 
 
</project>

package com.redis;
 
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.scheduling.annotation.EnableAsync;
 
/**
 * @Description:
 * @Author: Yourheart
 * @Create: 2023/2/28 14:38
 */
@SpringBootApplication
@EnableAsync
public class RedisApplication {
    public static void main(String[] args) {
 
        SpringApplication.run(RedisApplication.class, args);
 
    }
}

package com.redis.task;
 
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.EnableScheduling;
import org.springframework.scheduling.annotation.Scheduled;
 
import java.util.UUID;
import java.util.concurrent.TimeUnit;
 
/**
 * @Description:
 * @Author: Yourheart
 * @Create: 2023/2/28 14:51
 */
@Configuration      //1.主要用于标记配置类，兼备Component的效果。
@EnableScheduling   // 2.开启定时任务
@Slf4j
public class RedisTimeTask {
 
 
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
 
 
    @Scheduled(cron = "${timed.task}")//每天上午9点，下午5点执行
 
    /**
     * 单位都是毫秒
     */
   // @Scheduled(initialDelay = 5000,fixedRate=5000)
 
   // @Scheduled(initialDelay = 5000,fixedRate=20000)
    @Async
    public void timerSendMessage(){
        String lockKey="test_001";
//        Boolean setIfAbsent = stringRedisTemplate.opsForValue().setIfAbsent(lockKey, "001");
//        stringRedisTemplate.expire(lockKey,25, TimeUnit.SECONDS);
 
        Boolean setIfAbsent = stringRedisTemplate.opsForValue().setIfAbsent(lockKey, "001", 25, TimeUnit.SECONDS);
 
        if (setIfAbsent){
 
            try {
 
                log.info("测试redis的分布式锁成功....");
 
            } finally {
               stringRedisTemplate.delete(lockKey);
            }
        }
 
    }
}

server.port=8081
 
# 当天17点25分0秒
#timed.task=0 05,10,15,20,25,30,35,40,45,50,55 * * * *
#每隔15秒执行一次
timed.task=0/15 * * * * *
 
#timed.task= 0 0/5 * * * *
 
#redis配置
spring.redis.host=127.0.0.1
spring.redis.port=6380
spring.redis.database=1
spring.redis.jedis.pool.max-active=8
spring.redis.jedis.pool.min-idle=0
spring.redis.password=
spring.redis.lettuce.pool.max-wait=1000
 
logging.level.com.redis=debug
logging.level.web=debug
spring.devtools.add-properties=false