public <T> T get(String url) {
        List<String> urls = WMCollections.newArrayList(url);
        List<T> resultItemses = getAll(urls);
        if (resultItemses != null && resultItemses.size() > 0) {
            return resultItemses.get(0);
        } else {
            return null;
        }
    }
Download urls synchronizing.

@param urls urls
@param <T> type of process result
@return list downloaded
webmagic-core/src/main/java/us/codecraft/webmagic/Spider.java