redis 加锁与释放锁（分布式锁1）

使用Redis的 SETNX 命令可以实现分布式锁

SETNX key value

返回值

返回整数，具体为 
- 1，当 key 的值被设置 
- 0，当 key 的值没被设置

分布式锁使用

import redis.clients.jedis.Jedis;
import redis.clients.jedis.JedisPool;
import redis.clients.jedis.JedisPoolConfig;

/**
 * @Author: feng
 * @Date: 2019/5/25 21:54
 * @Description:
 */
public class RedisManager {

    private static JedisPool jedisPool;

    static {
        JedisPoolConfig jedisPoolConfig = new JedisPoolConfig();
        jedisPoolConfig.setMaxTotal(18);
        jedisPoolConfig.setMaxIdle(5);
        jedisPool = new JedisPool(jedisPoolConfig,"127.0.0.1",6379,5000);
    }

    public static Jedis getJedis() throws Exception {
        if (null != jedisPool){
            return jedisPool.getResource();
        }
        throw new Exception("Jedispool was not init");
    }
}

　　

import redis.clients.jedis.Jedis;
import redis.clients.jedis.Transaction;

import java.util.List;

/**
 * @Author: feng
 * @Date: 2019/5/25 22:04
 * @Description:
 */
public class RedisLock {

    public String getLock(String key, int timeout) {
        Jedis jedis = null;
        try {
            jedis = RedisManager.getJedis();
//            String value = UUID.randomUUID().toString();
            //以当前线程id作为value
            String value = String.valueOf(Thread.currentThread().getId());
            long end = System.currentTimeMillis() + timeout;
            while (System.currentTimeMillis() < end) {
                if (jedis.setnx(key, value) == 1) {
                    jedis.expire(key, timeout);
                    return value;
                }
                if (jedis.ttl(key) == -1) {
                    jedis.expire(key, timeout);
                }
                Thread.sleep(500);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            jedis.close();
        }
        return null;
    }

    public boolean releaseLock(String key, String value) {
        Jedis jedis = null;
        try {
            jedis = RedisManager.getJedis();
            while (true) {
                jedis.watch(key);
                System.out.println(jedis.get(key));
                if (value.equals(jedis.get(key))) {
                    Transaction transaction = jedis.multi();
                    transaction.del(key);
                    List<Object> list = transaction.exec();
                    if (list == null) {
                        continue;
                    }
                }
                jedis.unwatch();
                return true;
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            jedis.close();
        }
        return false;
    }

    public static void main(String[] args) {
        RedisLock redisLock = new RedisLock();
        String thredId = redisLock.getLock("test", 1000);
        System.out.println("返回值value:" + thredId);
        boolean b = redisLock.releaseLock("test", String.valueOf(Thread.currentThread().getId()));
        System.out.println(b);
    }

}