public void stop() {
        if (stat.compareAndSet(STAT_RUNNING, STAT_STOPPED)) {
            logger.info("Spider " + getUUID() + " stop success!");
        } else {
            logger.info("Spider " + getUUID() + " stop fail!");
        }
    }
Add urls with information to crawl.<br>

@param requests requests
@return this
webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java