import org.slf4j.Logger; import org.slf4j.LoggerFactory; import org.springframework.data.redis.core.RedisCallback; import org.springframework.data.redis.core.RedisTemplate; import org.springframework.stereotype.Component; import org.springframework.util.StringUtils; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisCluster; import redis.clients.jedis.JedisCommands; import javax.annotation.Resource; import java.util.ArrayList; import java.util.List; import java.util.UUID; /** * @author superchen * @since 2018/5/16 **/ @Component public class RedisDistributedLock{ @Resource private RedisTemplate<String, Object> redisTemplate; public static final String UNLOCK_LUA; static { StringBuilder sb = new StringBuilder(); sb.append("if redis.call(\"get\",KEYS[1]) == ARGV[1] "); sb.append("then "); sb.append(" return redis.call(\"del\",KEYS[1]) "); sb.append("else "); sb.append(" return 0 "); sb.append("end "); UNLOCK_LUA = sb.toString(); } private final Logger logger = LoggerFactory.getLogger(RedisDistributedLock.class); public boolean lock(String key, long expire, int retryTimes, long sleepMillis) { boolean result = setRedis(key, expire); // 如果获取锁失败，按照传入的重试次数进行重试 while ((!result) && retryTimes-- > 0) { try { logger.debug("lock failed, retrying..." + retryTimes); Thread.sleep(sleepMillis); } catch (InterruptedException e) { return false; } result = setRedis(key, expire); } return result; } public boolean setRedis(String key, long expire) { try { RedisCallback<String> callback = (connection) -> { JedisCommands commands = (JedisCommands) connection.getNativeConnection(); String uuid = UUID.randomUUID().toString(); return commands.set(key, uuid, "NX", "PX", expire); }; String result = redisTemplate.execute(callback); return !StringUtils.isEmpty(result); } catch (Exception e) { logger.error("set redis occured an exception", e); } return false; } public String get(String key) { try { RedisCallback<String> callback = (connection) -> { JedisCommands commands = (JedisCommands) connection.getNativeConnection(); return commands.get(key); }; String result = redisTemplate.execute(callback); return result; } catch (Exception e) { logger.error("get redis occured an exception", e); } return ""; } public boolean releaseLock(String key,String requestId) { // 释放锁的时候，有可能因为持锁之后方法执行时间大于锁的有效期，此时有可能已经被另外一个线程持有锁，所以不能直接删除 try { List<String> keys = new ArrayList<>(); keys.add(key); List<String> args = new ArrayList<>(); args.add(requestId); // 使用lua脚本删除redis中匹配value的key，可以避免由于方法执行时间过长而redis锁自动过期失效的时候误删其他线程的锁 // spring自带的执行脚本方法中，集群模式直接抛出不支持执行脚本的异常，所以只能拿到原redis的connection来执行脚本 RedisCallback<Long> callback = (connection) -> { Object nativeConnection = connection.getNativeConnection(); // 集群模式和单机模式虽然执行脚本的方法一样，但是没有共同的接口，所以只能分开执行 // 集群模式 if (nativeConnection instanceof JedisCluster) { return (Long) ((JedisCluster) nativeConnection).eval(UNLOCK_LUA, keys, args); } // 单机模式 else if (nativeConnection instanceof Jedis) { return (Long) ((Jedis) nativeConnection).eval(UNLOCK_LUA, keys, args); } return 0L; }; Long result = redisTemplate.execute(callback); return result != null && result > 0; } catch (Exception e) { logger.error("release lock occured an exception", e); } finally { // 清除掉ThreadLocal中的数据，避免内存溢出 //lockFlag.remove(); } return false; } }
