基于Redis分布式锁的实现代码

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.Transaction;
import redis.clients.jedis.exceptions.JedisException;
import java.util.List;
import java.util.UUID;

public class DistributedLock {
 private final JedisPool jedisPool;
 public DistributedLock(JedisPool jedisPool) {
 this.jedisPool = jedisPool;
 }
 
 public String lockWithTimeout(String locaName,
     long acquireTimeout, long timeout) {
 Jedis conn = null;
 String retIdentifier = null;
 try {
  // 获取连接
  conn = jedisPool.getResource();
  // 随机生成一个value
  String identifier = UUID.randomUUID().toString();
  // 锁名，即key值
  String lockKey = "lock:" + locaName;
  // 超时时间，上锁后超过此时间则自动释放锁
  int lockExpire = (int)(timeout / 1000);
  // 获取锁的超时时间，超过这个时间则放弃获取锁
  long end = System.currentTimeMillis() + acquireTimeout;
  while (System.currentTimeMillis() < end) {
  if (conn.setnx(lockKey, identifier) == 1) {
   conn.expire(lockKey, lockExpire);
   // 返回value值，用于释放锁时间确认
   retIdentifier = identifier;
   return retIdentifier;
  }
  // 返回-1代表key没有设置超时时间，为key设置一个超时时间
  if (conn.ttl(lockKey) == -1) {
   conn.expire(lockKey, lockExpire);
  }
  try {
   Thread.sleep(10);
  } catch (InterruptedException e) {
   Thread.currentThread().interrupt();
  }
  }
 } catch (JedisException e) {
  e.printStackTrace();
 } finally {
  if (conn != null) {
  conn.close();
  }
 }
 return retIdentifier;
 }
 
 public boolean releaseLock(String lockName, String identifier) {
 Jedis conn = null;
 String lockKey = "lock:" + lockName;
 boolean retFlag = false;
 try {
  conn = jedisPool.getResource();
  while (true) {
  // 监视lock，准备开始事务
  conn.watch(lockKey);
  // 通过前面返回的value值判断是不是该锁，若是该锁，则删除，释放锁
  if (identifier.equals(conn.get(lockKey))) {
   Transaction transaction = conn.multi();
   transaction.del(lockKey);
   List<Object> results = transaction.exec();
   if (results == null) {
   continue;
   }
   retFlag = true;
  }
  conn.unwatch();
  break;
  }
 } catch (JedisException e) {
  e.printStackTrace();
 } finally {
  if (conn != null) {
  conn.close();
  }
 }
 return retFlag;
 }
}