How to use Redis command "bitcount" in java

I am trying to use redis bitmap to save online user, use command "bitcount onlineUser" to count the number of online user.I use RedisTemplate to deal with redis. But I can't find any API in RedisTemplate to execute command "bitcount'.How can I execute command "bitcount" in java? Any help will be appreciated.

 @Override
    public Boolean saveOnlineUser(Long userId) {
        ValueOperations<String,Object> ops = redisTemplate.opsForValue();
        return ops.setBit("onlineUser",userId,true);
    }

    @Override
    public Integer getOnlineUser() {
        //I want to use Redis command "bitcount 'onlineUser'" here to count the number of online users
        return redisTemplate.opsForValue().;
    }