Session（重点）

服务器会给每一个用户（浏览器）创建一个Session对象；一个Session独占一个浏览器，只要浏览器没有关闭，这个Session就存在；用户登陆之后，整个网站它都可以访问-------->保存用户的信息；保存购物车的信息

cookie是把用户的数据写给用户的浏览器，浏览器保存（可以保存多个）Session把用户的数据写到用户独占Session中，服务器端保存（保存重要的信息，减少服务器资源的浪费）Session对象由服务器创建；cookie： Session：

保存一个登陆用户的信息；购物车信息；在整个项目中经常会使用的数据，我们将它保存在Session中； 使用Session

SessionDemo01.java

package com.godairo.servlet;

import pojo.Person;

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;

public class SessionDemo01 extends HttpServlet {

		@Override
		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
				//解决乱码
				request.setCharacterEncoding("UTF-8");
				request.setCharacterEncoding("UTF-8");
				response.setContentType("text/html;charset=utf-8");
				//得到Session
				HttpSession session = request.getSession();
				
				//给Session中存东西
				session.setAttribute("name",new Person("小可爱",23));
				
				//获取Session的ID
				String sessionid = session.getId();
				
				//判断Session是不是新创建的
				if (session.isNew()){
						response.getWriter().write("session创建成功，ID为："+sessionid);
				}else {
						response.getWriter().write("session已经在服务器中存在，ID为："+sessionid);
				}
				
				//Session创建的时候做了什么事情？
//				cookie cookie = new cookie("JSESSIONID",sessionid);
//				response.addcookie(cookie);

		}

		@Override
		protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
				super.doGet(req, resp);
		}
}

SessionDemo02.java

package com.godairo.servlet;

import pojo.Person;

import javax.servlet.ServletException;
import javax.servlet.http.*;
import java.io.IOException;

public class SessionDemo02 extends HttpServlet {

		@Override
		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
				//解决乱码
				request.setCharacterEncoding("UTF-8");
				request.setCharacterEncoding("UTF-8");
				response.setContentType("text/html;charset=utf-8");
				//得到Session
				HttpSession session = request.getSession();

				Person person = (Person) session.getAttribute("name");

				System.out.println(person.toString());
				response.getWriter().write(person.toString());

		}

		@Override
		protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
				super.doGet(req, resp);
		}
}

SessionDemo03.java

package com.godairo.servlet;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
import java.io.IOException;

public class SessionDemo03 extends HttpServlet {

		@Override
		protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
				HttpSession session = request.getSession();
				session.removeAttribute("name");
				//手动注销Session
				session.invalidate();
				
		}

		@Override
		protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
				doGet(req, resp);
		}
}

web.xml

        
        
                cookieDemo01
                com.godairo.servlet.cookieDemo01
        
        
        
                cookieDemo01
                /c1
        


        
                cookieDemo02
                com.godairo.servlet.cookieDemo02
        

        
                cookieDemo02
                /c2
        

        
                cookieDemo03
                com.godairo.servlet.cookieDemo03
        

        
                cookieDemo03
                /c3
        

        
                SessionDemo01
                com.godairo.servlet.SessionDemo01
        

        
                SessionDemo01
                /s1
        

        
        SessionDemo02
        com.godairo.servlet.SessionDemo02


        
                SessionDemo02
                /s2
        

        
                SessionDemo03
                com.godairo.servlet.SessionDemo03
        

        
                SessionDemo03
                /s3
        
        
        
        
                
                1
        

        
        1