code: protected String parseRequestUriWithoutContextPath(HttpServletRequest req){
          String requestUri = req.getRequestURI();
          String contextPath = req.getContextPath();
          requestUri = requestUri.substring(contextPath.length());
          if(requestUri.startsWith("/")){
              return requestUri;
          }else {
              return "/"+requestUri;
          }
      }
docs: 返回一个不包含contextPath的请求路径，如:<code>/ssoclient/login</code>