package com.session.homework;

import cn.hutool.core.date.DateUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Calendar;
import java.util.Date;


@WebServlet("/sessionHomework02")
public class SessionHomework02 extends HttpServlet
{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        /**
         * 1.解决中文乱码
         */
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        /**
         * 1.使用Hutool工具类获取当前时间
         * 2.将时间格式化成对应的yyyy年MM月dd日 HH时mm分ss秒
         * 3.使用utf-8编码  timeFormatDateCoded= URLEncoder.encode(formatDate,"utf-8");
         * 4.使用utf-8解码  timeFormatDateDecode = URLDecoder.decode(value,"utf-8");
         */
        Date date = DateUtil.date(System.currentTimeMillis());
        String formatDate = DateUtil.format(date, "yyyy年MM月dd日 HH时mm分ss秒");
        String timeFormatDateCoded = URLEncoder.encode(formatDate, "utf-8");
        String timeFormatDateDecode = URLDecoder.decode(formatDate, "utf-8");
        /**
         * 1.登录时间存储在session中  timeFormatDate
         * 2.往session中装入属性  key(String) : value(Object))
         */
        HttpSession session = req.getSession();

        if (session.getAttribute("time")==null)
        {
            resp.getWriter().write("您好，欢迎您首次访问");
            session.setAttribute("time", timeFormatDateDecode);
        }
        else
        {
            resp.getWriter().write("欢迎回来，您上次访问时间为：" + session.getAttribute("time"));
        }

    }
}

package com.session.homework;

import cn.hutool.core.date.DateUtil;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.*;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.util.Calendar;
import java.util.Date;


@WebServlet("/sessionHomework02")
public class SessionHomework02 extends HttpServlet
{
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
    {
        /**
         * 1.解决中文乱码
         */
        req.setCharacterEncoding("utf-8");
        resp.setContentType("text/html;charset=utf-8");
        /**
         * 1.使用Hutool工具类获取当前时间
         * 2.将时间格式化成对应的yyyy年MM月dd日 HH时mm分ss秒
         * 3.使用utf-8编码  timeFormatDateCoded= URLEncoder.encode(formatDate,"utf-8");
         * 4.使用utf-8解码  timeFormatDateDecode = URLDecoder.decode(value,"utf-8");
         */
        Date date = DateUtil.date(System.currentTimeMillis());
        String formatDate = DateUtil.format(date, "yyyy年MM月dd日 HH时mm分ss秒");
        String timeFormatDateCoded = URLEncoder.encode(formatDate, "utf-8");
        String timeFormatDateDecode = URLDecoder.decode(formatDate, "utf-8");
        /**
         * 1.登录时间存储在session中  timeFormatDate
         * 2.往session中装入属性  key(String) : value(Object))
         */
        HttpSession session = req.getSession();
        if (session.getAttribute("time")==null)
        {
            resp.getWriter().write("您好，欢迎您首次访问");
            session.setAttribute("time", timeFormatDateDecode);
        }
        else
        {
            /*
            *1.else也需要set一下当前时间
            * 2.这样便于下次访问的时候准确显示时间
            * 3.你set完就取不到之前的时间了，再取的话就是你刚set的时间
            */
            //  session.setAttribute("time", timeFormatDateDecode); 这里set取到的是之前的时间
            resp.getWriter().write("欢迎回来，您上次访问时间为：" + session.getAttribute("time"));
            session.setAttribute("time", timeFormatDateDecode);//这里set取到的是当前的时间

        }

    }
}