利用redis的transaction功能，实现分布式下加锁

wangyan188

package memcached;
import java.util.List;
import redis.clients.jedis.Jedis;
import redis.clients.jedis.Transaction;
public class TestJedisLock {
Jedis jedis = new Jedis("127.0.0.1", 6379);
public static void main(String[] args) {
TestJedisLock t = new TestJedisLock();
System.out.println(t.testLock());
}
public boolean testLock() {
String pk = "mypk";
String lockPk = "lock" + pk;  
String lockValue = String.valueOf(System.currentTimeMillis()) + "111";  
try {  
if(jedis.exists(lockPk)) { // other one locked already   
System.out.println("Already locked pk:" + pk);  
return false;  
}  
jedis.watch(lockPk);// make sure below operation is particle   
jedis.multi();  
Transaction trans = new Transaction(jedis.getClient());  
trans.set(lockPk, lockValue);  
trans.expire(lockPk, 60*60);  
List<Object> ret = trans.exec();  
if(ret == null) {  
System.out.println("Concurrent lock fail for pk:" + pk);  
return false;  
}  
String lockedValue = jedis.get(lockPk);  
return lockValue.equals(lockedValue); // locked success   
} catch (Exception e) {  
System.out.println("Exception in lock for pk:" + pk);   
return false;  
}
}
}