Cookie和Session详解

package cn.zjq.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("/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;//有lastTime的cookie

				//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);
				System.out.println("编码前："+str_date);
				//URL编码
				str_date = URLEncoder.encode(str_date,"utf-8");
				System.out.println("编码后："+str_date);
				cookie.setValue(str_date);
				//设置cookie的存活时间
				cookie.setMaxAge(60 * 60 * 24 * 30);//一个月
				response.addCookie(cookie);


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

				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);
		System.out.println("编码前："+str_date);
		//URL编码
		str_date = URLEncoder.encode(str_date,"utf-8");
		System.out.println("编码后："+str_date);

		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，欢迎您首次访问</h1>");
	}


}

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

Cookie c = new Cookie("JSESSIONID",session.getId());
c.setMaxAge(60*60);
response.addCookie(c);

<session-config>
	<session-timeout>30</session-timeout>
</session-config>