保存状态的两种方式

 

 

package com.bjsxt.cookie;

import java.io.IOException;
import java.net.URLEncoder;

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;

/**
 * Servlet implementation class TestSetCookie
 */
@WebServlet("/TestSetCookie")
public class TestSetCookie extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
    System.out.println("TestSetCookie.service()");
    //创建cookie
    Cookie cookie01=new Cookie("vivo","vivox5");
    Cookie cookie02=new Cookie("vivo","vivox6");
    Cookie cookie03=new Cookie("vivo","vivox7");
    Cookie cookie04=new Cookie("vivo","vivox21");
    //设置中文编码cookie
    Cookie cookie05=new Cookie("vivo",URLEncoder.encode("步步高五","utf-8"));
    //设置cookie信息的有效期,setmaxage是以秒为单位
    cookie03.setMaxAge(3*24*3600);
    cookie04.setMaxAge(3*24*3600);
    //设置cookie的访问路径
    cookie01.setPath(req.getContextPath()+"/abc");
    
    //发送给客户端
    resp.addCookie(cookie01);
    resp.addCookie(cookie02);
    resp.addCookie(cookie03);
    resp.addCookie(cookie04);
    resp.addCookie(cookie05);
    }
    

}

package com.bjsxt.cookie;

import java.io.IOException;
import java.net.URLDecoder;

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;

/**
 * Servlet implementation class TestGetCookie
 */
@WebServlet("/TestGetCookie")
public class TestGetCookie extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        System.out.println("TestGetCookie.service()");
        //获取cookie--获取请求头里的cookie（从浏览器获取）
        Cookie[] cookies=req.getCookies();
        //获取cookie的名称和值
        for(int i=0;i<cookies.length;i++){
            System.out.println("cookie:"+cookies[i].getName()+":"+ URLDecoder.decode(cookies[i].getValue(),"utf-8"));
        }
    }

}

 

session

 

package com.bjsxt.session;

import java.io.IOException;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
/**
 * session:将http状态信息保存在服务器端的技术
 * seesion是客户端和服务器之间的一次会话
 *   会话-开始：当用户第一访问服务器时候就开始了
 *         结束：客户端--关闭浏览器（清除cookie）
 *           服务器--A:超过有效期 在tomcat中web.xml中配置   <session-config>
                                                    <session-timeout>30</session-timeout>
                                                 </session-config>
 *                   B:在本项目中web.xml配置session-config
 *                  C:设置session的最大不活动周期
 *                  D:服务器关闭
 *   
 *
 * cookie:不安全，效率低，容量小，但是不能舍弃这门技术，因为session的跟踪机制需要cookie来保存JSESSIONID
 */
@WebServlet("/HelloSession")
public class HelloSession extends HttpServlet {

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        System.out.println("HelloSession.service()");
        
        //获取session
        HttpSession hs = req.getSession();
        
        //设置sesssion的最大不活动周期
        //hs.setMaxInactiveInterval(10);
        
        //强制sesssion失效
        //hs.setMaxInactiveInterval(0);
        //hs.invalidate();
        
        //获取sessionid
        String hsid = hs.getId();
        System.out.println("HelloSession.service()sessionid:"+hsid);
        
    }

    
}