@RequestMapping("/url_bypass")
@ResponseBody
public String url_bypass(HttpServletRequest request) throws Exception{
    String url = request.getParameter("url");
    System.out.println("url:  " + url);
    URL u = new URL(url);
    // 判断是否是http(s)协议
    if (!u.getProtocol().startsWith("http") && !u.getProtocol().startsWith("https")) {
        return "Url is not http or https";
    }
    String host = u.getHost().toLowerCase();
    System.out.println("host:  " + host);
    if (host.endsWith("." + "joychou.org")) {
        return "good url";
    } else {
        return "bad url";
    }
}