I just download this page.
http://search.jd.com/Search?keyword=%E6%96%87%E5%AD%A6&enc=utf-8&area=22&book=y
it do not send a header of charset in http response header and I put it content to Crawler::addContent,Then Crawler use wrong charset ISO-8859-1.
It works fine if I use follow code:

        $crawler = new Crawler();
        $crawler->addHtmlContent($content,'GBK');

Is there some way to guess charset from html meta?