crawler.setBackground(true);
            ((UrlFilterImpl) crawler.urlFilter).setIncludeFilteringPattern("$1$2$3.*");
            crawler.addUrl(url);
            crawler.getCrawlerContext().setMaxAccessCount(maxCount);
            crawler.getCrawlerContext().setNumOfThread(numOfThread);
            final String sessionId = crawler.execute();
            Thread.sleep(3000);

                    if (crawlerList.get(i).getCrawlerContext().getStatus() == CrawlerStatus.DONE
                            && Constants.RUNNING.equals(crawlerStatusList.get(i))) {
                        crawlerList.get(i).awaitTermination();
                        crawlerStatusList.set(i, Constants.DONE);
                        final String sid = crawlerList.get(i).getCrawlerContext().getSessionId();

            crawler.setBackground(true);
            ((UrlFilterImpl) crawler.urlFilter).setIncludeFilteringPattern("$1$2$3.*");
            crawler.addUrl(url);
            crawler.getCrawlerContext().setMaxAccessCount(maxCount);
            crawler.getCrawlerContext().setNumOfThread(numOfThread);
            final String sessionId = crawler.execute();
            Thread.sleep(3000);

            // not support robots.txt
            return;
        }

        // crawler context
        final CrawlerContext crawlerContext = CrawlingParameterUtil.getCrawlerContext();
        if (crawlerContext == null) {
            // wrong state
            return;
        }

        final int idx = url.indexOf('/', url.indexOf("://") + 3);
        String hostUrl;