session是客户端和服务端的一次会话
web的session是指用户在浏览某个网站时，从进入网站到关闭浏览器的这段时间，uyejiushi用户浏览这个网站所花费的时间。
session是一个时间的概念
在服务器的内存中保存着不同用户的session
session_page1.jsp
<%@ page language="java" import="java.util.*,java.text.*" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP 'exersice.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <h1>session内置对象</h1> <hr> <% SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日 HH:mm:ss"); Date d = new Date(session.getCreationTime()); session.setAttribute("username","admin"); session.setAttribute("password","123456"); session.setAttribute("age",20); //设置当前session最大生存期限 session.setMaxInactiveInterval(10);//10秒钟，是秒过后再跳转则session不再保存 %> Session创建时间：<%=sdf.format(d) %><br> Session的ID编号：<%=session.getId() %><br> 从Session中换取用户名：<%=session.getAttribute("username") %><br> <a href = "session_page2.jsp" target = "_blank_">跳转</a> </body> </html>
session_page2.jsp
<%@ page language="java" import="java.util.*,java.text.*" contentType="text/html; charset=utf-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP 'exersice.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <h1>page2</h1> Session的ID编号：<%=session.getId() %><br> 从Session中换取用户名：<%=session.getAttribute("username") %><br> Session中保存的属性有：<% String[] names = session.getValueNames(); for(int i = 0;i<names.length;i++){ out.println(names[i]+"  "); }; %> <br> </body> </html>
