带你轻松掌握Redis分布式锁

int tag = random.nextint()//随机数
boolean nx=true;
int ex=5;
if(redis.set(key, tag, nx, ex)){
    do_something()
    redis.delifequals(key, tag)//不存在这样的命令
}

#delifequals.lua文件，下面的是社区热门代码
if redis.call('get', KEYS[1]) == ARGV[1] then
    return redis.call('del', KEYS[1])
else
    return 0
end
//java调用
public void delifequals(){
    String script = readScript("delifequals.lua");
    int tag = 5;
    String key = "key";
    Object eval = jedis.eval(script, Lists.newArrayList(key), Lists.newArrayList(tag));
    System.out.println(eval);
}

public class JedisWithReentrantLock {
    private Jedis jedis;
    /**
     * 当前线程的锁及计数
     */
    private ThreadLocal<Map<String, Integer>> lockers = new ThreadLocal<>();
    public JedisWithReentrantLock(Jedis jedis) {
        this.jedis = jedis;
    }
    private boolean set(String key) {
        return jedis.set(key, "", "nx", "ex", 5L) != null;
    }
    private void del(String key) {
        jedis.del(key);
    }
    private Map<String, Integer> getLockers() {
        Map<String, Integer> refs = lockers.get();
        if (refs != null) {
            return refs;
        }
        lockers.set(Maps.newHashMap());
        return lockers.get();
    }
 
    public boolean lock(String key) {
        Map<String, Integer> refs = getLockers();
        Integer refCount = refs.get(key);
        if (refCount != null) {
            refs.put(key, refCount + 1);
            return true;
        }
        if (!this.set(key)) {
            return false;
        }
        refs.put(key, 1);
        return true;
    }
 
    public boolean unlock(String key) {
        Map<String, Integer> refs = getLockers();
        Integer refCount = refs.get(key);
        if (refCount == null) {
            return false;
        }
        refCount -= 1;
        if (refCount > 0) {
            refs.put(key, refCount);
        } else {
            refs.remove(key);
            this.del(key);
        }
        return true;
    }
}
    @Test
    public void runJedisWithReentrantLock() {
        JedisWithReentrantLock redis = new JedisWithReentrantLock(jedis);
        System.out.println(redis.lock("alex"));
        System.out.println(redis.lock("alex"));
        System.out.println(redis.unlock("alex"));
        System.out.println(redis.unlock("alex"));
    }