请求对象HttpServletRequest——获取请求头信息的方法

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        String connection = req.getHeader("connection");
        System.out.println(connection);

        Enumeration<String> values = req.getHeaders("accept-encoding");
        while (values.hasMoreElements()) {
            String value = values.nextElement();
            System.out.println(value);
        }

        Enumeration<String> names = req.getHeaderNames();
        while (names.hasMoreElements()) {
            String value = req.getHeader(names.nextElement());
            System.out.println(value);
        }
    }