请求对象HttpServletRequest——获取请求参数信息

@Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

        System.out.println(req.getParameter("userName"));
        System.out.println("------------------");

        String[] parameterValues = req.getParameterValues("hobby");
        for (String hobby : parameterValues) {
            System.out.println(hobby);
        }
        System.out.println("------------------");

        Enumeration<String> names = req.getParameterNames();
        while (names.hasMoreElements()) {
            String name = names.nextElement();
            System.out.println(req.getParameter(name));
        }
        System.out.println("------------------");

        Map<String, String[]> map = req.getParameterMap();
        for (String key : map.keySet()) {
            String[] values = map.get(key);
            System.out.print(key + ":");
            for (String value : values) {
                System.out.print(value + " ");
            }
            System.out.println();
        }

    }