Cookie to obtain client information and response

Personal blog address https://nfreak-man.cn
When the user is not logged in, cookies are often used to complete the province identification of the client to the server and save some settings.

The following is a simple function to record the user's last access time.

@WebServlet("/cookieTest")
public class CookieTest extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //设置响应的消息体的数据格式以及编码
        response.setContentType("text/html;charset=utf-8");

        //1.获取所有cookie
        Cookie[] cookies = request.getCookies();
        boolean flag = false;//没有cookie为lastTime
        //2.遍历cookie数组
        if (cookies != null && cookies.length > 0){
            for (Cookie cookie : cookies) {
                //3.获取cookie的名称
                String name = cookie.getName();
                //4.判断名称是否是：lastTime
                if ("lastTime".equals(name)){
                    //有该cookie，不是第一次访问
                    flag = true;

                    //响应数据
                    //获取cookie的value，时间
                    String value = cookie.getValue();
                    //URL解码
                    value = URLDecoder.decode(value,"utf-8");
                    response.getWriter().write("<h1>欢迎回来，您上次访问时间为："+value+"<h1>");

                    //设置cookie的value
                    //获取当前时间的字符串，重新设置cookie的值，重新发送cookie
                    Date date = new Date();
                    SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日HH:mm:ss");
                    String str_date = sdf.format(date);
                    //URL编码
                    str_date = URLEncoder.encode(str_date, "utf-8");
                    cookie.setValue(str_date);
                    //设置cookie的存活时间
                    cookie.setMaxAge(60 * 60 * 24 * 30);//一个月
                    response.addCookie(cookie);



                    break;
                }
            }
        }
        if (cookies == null || cookies.length == 0 || flag == false){
            //没有，第一次访问
            //设置cookie的value
            //获取当前时间的字符串，重新设置cookie的值，重新发送cookie
            Date date = new Date();
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss");
            String str_date = sdf.format(date);
            //URL编码
            str_date = URLEncoder.encode(str_date, "utf-8");
            Cookie cookie = new Cookie("lastTime",str_date);
            //设置cookie的存活时间
            cookie.setMaxAge(60 * 60 * 24 * 30);//一个月
            response.addCookie(cookie);

            response.getWriter().write("<h1>您好，欢迎首次访问<h1>");
        }
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }
}