过滤器 禁止直接访问静态文件

 HttpServletRequest req = (HttpServletRequest) request; HttpServletResponse res = (HttpServletResponse) response; String uri = req.getRequestURI();if (uri.indexOf("/css/") != -1                && req.getHeader("referer") == null) {            res.sendError(HttpServletResponse.SC_FORBIDDEN);}