Spring整合Redis分布式锁

Posted 2021-12-03 monkey66

1.导包

<spring.boot.version>2.2.6.RELEASE</spring.boot.version>

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
    <version>${spring.boot.version}</version>
</dependency>

<dependency>
    <groupId>org.apache.commons</groupId>
    <artifactId>commons-pool2</artifactId>
    <version>2.6.2</version>
</dependency>

2.工具类

@Slf4j
@Component
public class RedisUtils {


    @Autowired
    private StringRedisTemplate redisTemplate;

    /**
     * 上锁 将键值对设定一个指定的时间timeout.
     *
     * @param key
     * @param timeout 键值对缓存的时间，单位是秒
     * @return 设置成功返回true，否则返回false
     */
    public boolean tryLock(String key, String value, long timeout) {
        //底层原理就是Redis的setnx方法
        boolean isSuccess = redisTemplate.opsForValue().setIfAbsent(key, value);
        if (isSuccess) {
            //设置分布式锁的过期时间
            redisTemplate.expire(key, timeout, TimeUnit.SECONDS);
        }
        return isSuccess;
    }

    public void del(String... key) {
        if (key != null && key.length > 0) {
            if (key.length == 1) {
                redisTemplate.delete(key[0]);
            } else {
                redisTemplate.delete(CollectionUtils.arrayToList(key));
            }
        }
    }

    public Object get (String key) {
        if (key != null) {
            return redisTemplate.opsForValue().get(key);
        }
        return null;
    }
}

 

3.使用

 

@Scheduled(cron = "*/5 * * ? * *")
    public void globalStatCache (){

        //-------------上分布式锁开始-----------------

        InetAddress addr = null;
        try {
            addr = InetAddress.getLocalHost();
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }
        //获取本机ip
        String ip = addr.getHostAddress();
        //默认上锁时间为五小时
        //此key存放的值为任务执行的ip，
        // redis_default_expire_time 不能设置为永久，避免死锁
        boolean lock = redisUtils.tryLock(redisKey, ip, redis_default_expire_time);
        log.info("============定时任务开始==============");

        if (lock) {

            //具体代码.........
    
            try {
                Thread.sleep(1000*60);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            redisUtils.del(redisKey);
            log.info("============本次定时任务结束==============");
            //三个月
        }else {
            log.info("============获得分布式锁失败=======================");
            ip = (String) redisUtils.get(redisKey);
            log.info("============{}机器上占用分布式锁，聚类任务正在执行=======================", ip);
            return;
        }


    }