来源：腾讯云
2023-04-22 10:26:40
(资料图片)
在此之前，去看了下Redission的实现原理，不过在开发中，原本的代码使用RedistTemplate实现的，也不太想换，所以我想了下，不如自己实现要给WatchDog。
我的想法是，在用户加上锁的时候开启个定时任务线程，并且在定时任务中，判断原线程isAlive状态进行“续命”。
下面是代码(在这里面为了方便，未使用的是HuTool.CornUtil来实现动态定时任务)：
/** * Title * * @ClassName: LockUtil * @Description:锁工具类,通过内部枚举类实现单例，防止反射攻击 * @author: Karos * @date: 2023/1/4 0:17 * @Blog: https://www.wzl1.top/ */package cn.katool.lock;import cn.hutool.core.util.BooleanUtil;import cn.hutool.core.util.ObjectUtil;import cn.hutool.cron.CronUtil;import cn.hutool.cron.task.Task;import cn.katool.Config.LockConfig;import cn.katool.Exception.ErrorCode;import cn.katool.Exception.KaToolException;import cn.katool.other.MethodIntefaceUtil;import com.qiniu.util.StringUtils;import lombok.SneakyThrows;import lombok.extern.slf4j.Slf4j;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Scope;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.stereotype.Component;import org.springframework.util.ObjectUtils;import javax.annotation.Resource;import java.util.concurrent.ConcurrentHashMap;import java.util.concurrent.TimeUnit;@Component@Scope("prototype")@Slf4jpublic class LockUtil { @Resource RedisTemplate redisTemplate; private LockUtil(){ } private static boolean isOpenCorn=false; /** * 带看门狗机制上锁 * @param lockObj * @return */ public boolean DistributedLock(Object lockObj){ try { return DistributedLock(lockObj,null,null); } catch (KaToolException e) { throw new RuntimeException(e); } } @Resource LockConfig lockConfig; //加锁 /** * 无看门狗机制上锁 * @param obj * @param exptime * @param timeUnit * @return * @throws KaToolException */ public boolean DistributedLock(Object obj,Long exptime,TimeUnit timeUnit) throws KaToolException { if (ObjectUtil.isEmpty(obj)){ throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空"); } Boolean isDelay=false; if (ObjectUtil.isAllEmpty(exptime,timeUnit)){ isDelay=true; } if(ObjectUtil.isEmpty(exptime)){ exptime= lockConfig.getInternalLockLeaseTime();; } if (ObjectUtils.isEmpty(timeUnit)){ timeUnit=lockConfig.getTimeUnit(); } //线程被锁住了，就一直等待 DistributedAssert(obj); Boolean aBoolean = redisTemplate.opsForValue().setIfAbsent("Lock:"+obj.toString(), "1", exptime, timeUnit); log.info("katool=> LockUntil => DistributedLock:{} value:{} extime:{} timeUnit:{}",obj.toString(), "1", exptime, timeUnit); //实现看门狗 if (isDelay){ if (LockUtil.isOpenCorn==false){ //如果同一个项目之前打开过，那么先关闭，避免重复启动 CronUtil.stop(); //支持秒级别定时任务 CronUtil.setMatchSecond(true); //定时服务启动 CronUtil.start(); LockUtil.isOpenCorn=true; } Thread thread = Thread.currentThread(); TimeUnit finalTimeUnit = timeUnit; Long finalExptime = exptime; class TempClass{ public String scheduleId; } final TempClass tempClass = new TempClass(); tempClass.scheduleId=CronUtil.schedule("0/30 * * * * ?", new Task() { @SneakyThrows @Override public void execute() { boolean alive = thread.isAlive(); if (alive) { delayDistributedLock(obj, finalExptime>=3?(finalExptime / 3):finalExptime, finalTimeUnit); return; } else { if (tempClass.scheduleId==null||"".equals(tempClass.scheduleId)){ return; } CronUtil.remove(tempClass.scheduleId); DistributedUnLock(obj); return; } } }); } return BooleanUtil.isTrue(aBoolean); } //检锁 public void DistributedAssert(Object obj) throws KaToolException { if (ObjectUtils.isEmpty(obj)){ throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空"); } while(true){ Object o = redisTemplate.opsForValue().get("Lock:" + obj.toString()); if (ObjectUtils.isEmpty(o))return; } } //延期 public boolean delayDistributedLock(Object obj,Long exptime,TimeUnit timeUnit) throws KaToolException { if (ObjectUtils.isEmpty(obj)){ throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空"); } Boolean aBoolean = redisTemplate.opsForValue().setIfPresent("Lock:"+obj.toString(), "1", exptime, timeUnit); log.info("katool=> LockUntil => delayDistributedLock:{} value:{} extime:{} timeUnit:{}",obj.toString(), "1", exptime, timeUnit); return BooleanUtil.isTrue(aBoolean); } //释放锁 public boolean DistributedUnLock(Object obj) throws KaToolException { if (ObjectUtils.isEmpty(obj)){ throw new KaToolException(ErrorCode.PARAMS_ERROR," Lock=> 传入obj为空"); } Boolean aBoolean = redisTemplate.delete("Lock:" + obj.toString()); log.info("katool=> LockUntil => unDistributedLock:{} isdelete:{} ",obj.toString(),true); return BooleanUtil.isTrue(aBoolean); } //利用枚举类实现单例模式，枚举类属性为静态的 private enum SingletonFactory{ Singleton; LockUtil lockUtil; private SingletonFactory(){ lockUtil=new LockUtil(); } public LockUtil getInstance(){ return lockUtil; } } @Bean("LockUtil") public static LockUtil getInstance(){ return SingletonFactory.Singleton.lockUtil; }}关键词：
