求解为何jsoup抓取时报503

elemt=Jsoup.connect("http://61.142.33.204/default4.aspx")
                .userAgent("Mozilla/5.0 (Windows NT 6.1; WOW64; rv:56.0) Gecko/20100101 Firefox/56.0")

                .header("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8")
                .header("Accept-Language","zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3")
                .header("Accept-Encoding", "gzip, deflate")
                .header("Connection","keep-alive")
                .header("Upgrade-Insecure-Requests", "1")
                .get();

对照浏览器访问网站同时抓包的结果，看尼的请求有什么不同。比如useragent referer cookie postdata等，以及你是否频繁提交而服务器有限制。