redis 设置分布式锁

public static boolean acquireLock ( String lock ) {

     // 1. 通过SETNX试图获取一个lock

     boolean success = false ;

     Jedis jedis = pool . getResource ( ) ;       

     long value = System . currentTimeMillis ( ) + expired + 1 ;     

     System . out . println ( value ) ;     

     long acquired = jedis . setnx ( lock , String . valueOf ( value ) ) ;

     //SETNX成功，则成功获取一个锁

     if ( acquired == 1 )       

         success = true ;

     //SETNX失败，说明锁仍然被其他对象保持，检查其是否已经超时

     else {

         long oldValue = Long . valueOf ( jedis . get ( lock ) ) ;

 

         //超时

         if ( oldValue < System . currentTimeMillis ( ) ) {

             String getValue = jedis . getSet ( lock , String . valueOf ( value ) ) ;               

             // 获取锁成功

             if ( Long . valueOf ( getValue ) == oldValue )

                 success = true ;

             // 已被其他进程捷足先登了

             else

                 success = false ;

         }

         //未超时，则直接返回失败

         else             

             success = false ;

     }         

     pool . returnResource ( jedis ) ;

     return success ;       

}

 

//释放锁

public static void releaseLock ( String lock ) {

     Jedis jedis = pool . getResource ( ) ;       

     long current = System . currentTimeMillis ( ) ;       

     // 避免删除非自己获取得到的锁

     if ( current < Long . valueOf ( jedis . get ( lock ) ) )

         jedis . del ( lock ) ;       

     pool . returnResource ( jedis ) ;

}



//--------------------------

public Long acquireLock(final String lockName,final long expire){
    return redisTemplate.execute(new RedisCallback<Long>() {
     public Long doInRedis(RedisConnection connection) {
        byte[] lockBytes = redisTemplate.getStringSerializer().serialize(lockName);
boolean locked = connection.setNX(lockBytes, lockBytes);
connection.expire(lockBytes, expire);
if(locked){
return 1L;
}
            return 0L;
}
});
}


//原子操作 -----------------------

public String getAndSet(final String key,final String value){
return redisTemplate.execute(new RedisCallback<String>() {
@Override
public String doInRedis(RedisConnection connection)
throws DataAccessException {
byte[] result = connection.getSet(redisTemplate.getStringSerializer().serialize(key),
redisTemplate.getStringSerializer().serialize(value));
if(result!=null){
                                     return new String(result);
  }

return null;
                    }
          });

}