后面检测网站是否挂掉

用ajax发送同步请求来判断网站是否挂掉不能解决跨域访问的问题。。
可以在后台用定时任务去检测试
代码如下：
  public void httpConnetion(String urlStr,AsformwebSite webSite) {
        URL url = null;
        try {
            url = new URL(urlStr);
            URLConnection URLconnection = url.openConnection();
            HttpURLConnection httpConnection = (HttpURLConnection) URLconnection;
            int responseCode = httpConnection.getResponseCode();
            System.out.println(responseCode);
            if (responseCode == HttpURLConnection.HTTP_OK) {//HTTP_OK 为200
            } else {
                //oa提醒
                addRemind(webSite);
                //短信提醒
                sendSm(webSite.getF5(),"网站'"+webSite.getF2()+"'出现异常，请检查网站服务！");
            }
        } catch (Exception e) {
            //oa提醒
            addRemind(webSite);
            //短信提醒
            sendSm(webSite.getF5(),"网站'"+webSite.getF2()+"'出现异常，请检查网站服务！");
        }
    }