添加Cookies和Session的代码

package Cookies;
public class AddCookies extends HttpServlet {

    /**
     * @author Administrator
     */    private static final long serialVersionUID = 1L;

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        // Session
        HttpSession session = req.getSession();
        session.setAttribute("Lckiss", "Session NotPass");
        // Cookies
        Cookie C = new Cookie("Lckiss", "Cookies Pass");
        // C.setPath("/Cookies/");
        C.setMaxAge(60 * 60 * 24);
        resp.addCookie(C);

        resp.setContentType("text/html;charset=utf-8");
        PrintWriter out = resp.getWriter();
        out.println("<h3>已添加一个Cookies</h3>");
        out.println("<h3>已生成一个Session</h3>");
    }
}

 读取Cookies和Session的代码

package Cookies;

public class ReadCookies extends HttpServlet {

    /**
     * @author Administrator
     */    private static final long serialVersionUID = 1L;

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter out = resp.getWriter();
        Cookie MYCookies[] = req.getCookies();

        out.println("<h3>以下为Cookies数据</h3>");
        out.println(MYCookies.length);
        for (int i = 0; i < MYCookies.length; i++) {
            Cookie C = MYCookies[i];
            out.println("<p>Cookies Name:" + C.getName() + " ");
            out.println("| Cookies Value:" + C.getValue() + "</p>");
            out.println("-----------");
            // out.println("<p>Cookies.getPath:" + C.getPath() + "</p>");
            // System.out.println(C.getVersion());
        }

        HttpSession S = req.getSession();
        Enumeration<String> Sname = S.getAttributeNames();
        String Svalue = S.getAttribute("Lckiss").toString();
        out.println("<h3>以下为Session数据</h3>");
        out.println("<p>Session Name:" + Sname.nextElement().toString() + " ");
        out.println("| Session Value:" + Svalue + "</p>");
    }
}

书上一个记录访问时间和访问次数的代码

package Cookies;

import java.io.IOException;
import java.io.PrintWriter;
import java.text.SimpleDateFormat;
import java.util.Date;

import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class VisitTimes extends HttpServlet {

    /**
     * @author Administrator
     */    private static final long serialVersionUID = 1L;

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        resp.setContentType("text/html;charset=utf-8");
        PrintWriter out = resp.getWriter();

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        String nowTime = sdf.format(new Date());
        String lastVistTime = "";
        int vistedCount = 0;
        // 获取所有的Cookies
        Cookie[] cookies = req.getCookies();
        if (cookies != null) {
            for (Cookie cookie : cookies) {
                // 判断是否为记录最近访问时间的Cookies
                if ("lastVistTime".equals(cookie.getName())) {
                    lastVistTime = cookie.getValue();
                }
                // 判断是否为记录访问次数的Cookies
                if ("VistedCount".equals(cookie.getName())) {
                    vistedCount = Integer.valueOf(cookie.getValue());
                }
            }
            System.out.println(vistedCount);
            // 若曾经访问过，输出上次访问时间
            if (!"".equals(lastVistTime))
                out.println("<p>您上次访问的时间是：" + lastVistTime + "</p>");
            // 输入访问次数
            out.println("<p>您是第" + (vistedCount + 1) + "次访问网站</p>");
            // 以本次访问时间重建同名新Cookies
            Cookie lastVistedTimeC = new Cookie("lastVistTime", nowTime);
            lastVistedTimeC.setMaxAge(60 * 60 * 24);
            // 以本次访问时间重建同名新Cookies
            Cookie VistedCountC = new Cookie("VistedCount", String.valueOf(vistedCount + 1));
            VistedCountC.setMaxAge(60 * 60 * 24);
            resp.addCookie(lastVistedTimeC);
            resp.addCookie(VistedCountC);

        }
    }
}

我的感觉就是Cookies是Session的一个载体，Cookies没了 Session也肯定没了，百度的结果如下

cookie 和session 的区别：

1、cookie数据存放在客户的浏览器上，session数据放在服务器上。

2、cookie不是很安全，别人可以分析存放在本地的COOKIE并进行COOKIE欺骗
  考虑到安全应当使用session。

3、session会在一定时间内保存在服务器上。当访问增多，会比较占用你服务器的性能
  考虑到减轻服务器性能方面，应当使用COOKIE。

4、单个cookie保存的数据不能超过4K，很多浏览器都限制一个站点最多保存20个cookie。

5、所以个人建议：
  将登陆信息等重要信息存放为SESSION
  其他信息如果需要保留，可以放在COOKIE中

 Anr-C 2016.10.28