10.Cookie

客户端缓冲数据技术
将数据储存在客户端，每次请求都携带Cookie数据进行访问

发送Cookie

        Cookie cookie = new Cookie("username","zs");
        resp.addCookie(cookie);

获取Cookie

        Cookie[] cookies = req.getCookies();
        for (Cookie cookie : cookies){
            String name = cookie.getName();
            String value = cookie.getValue();
        }