JavaWeb实战——记录网站上一次访问时间

帮助网站实现提示客户端计算机上次访问网站的时间

package net.wen.cookie;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URLDecoder;
import java.net.URLEncoder;
import java.text.SimpleDateFormat;
import java.util.Date;

@WebServlet(name = "TimeCookieServlet", urlPatterns = "/timeCookie")
public class TimeCookieServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html;charset=utf-8");

        //制作当前时间字符串
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd号，hh时mm分ss秒");
        String curdata = sdf.format(new Date());
        //因为我们即将传给cookie的值不能含有中文，所以进行编码
        curdata = URLEncoder.encode(curdata,"utf-8");

        Cookie[] cookies = request.getCookies();
        Cookie timeCookie = new Cookie("timeCookie", curdata);
        if(cookies!=null)//如果不是第一次访问
        {
            for (Cookie cookie : cookies) {
                if(cookie.getName().equals("timeCookie")){
                    String value = cookie.getValue();
                    //解码
                    value = URLDecoder.decode(value,"utf-8");
                    response.getWriter().write("上次访问时间："+value);
                    break;
                }
            }
        }
        if(cookies==null){//第一次访问
            response.getWriter().write("第一次访问");
        }
        timeCookie.setMaxAge(9999);
        response.addCookie(timeCookie);
    }
}