Session简单应用

来源：互联网发布：javascript isnan函数编辑：程序博客网时间：2024/05/15 22:28

实现一：在首页上添加“购买”、“结账”超链接，当用户点击“购买”，再点击“结账”后，在浏览器中输出用户购买的商品。

其核心“购买”Servlet为Demo1.java

package SessionDemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class Demo1 extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{HttpSession session = request.getSession();session.setAttribute("name","洗衣机");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}

其核心“结账”Servlet为：Demo2.java

package SessionDemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class Demo2 extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{//解决中文乱码问题request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");  PrintWriter out = response.getWriter();  HttpSession session = request.getSession();String productname = (String) session.getAttribute("name");out.write("您购买的商品为 ： "+productname);}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}

其显示页面为index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>  <title>Index.jsp</title>  </head>    <body>    <a href="/SessionTest/servlet/Demo1">购买</a></br>    <a href="/SessionTest/servlet/Demo2">结账</a></br>  </body></html>

在浏览器中加载index.jsp

点击“购买”后，再点击“结账”，会显示

实现二：摧毁Session。

方法一：在web.xml中配置Session的失效时间，此处配置为10分钟

<session-config>  <session-timeout>10</session-timeout>  </session-config>

方法二：在Servlet中加入如下代码摧毁：

//摧毁Sessionsession.invalidate();

实现三：在实现一中，当用户在点击“购买”后若关闭浏览器，则再次打开浏览器点击“结账”时会显示：null。利用Cookie解决此问题。

将Demo1.java改为如下

package SessionDemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.Cookie;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;public class Demo1 extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{HttpSession session = request.getSession();String sessionId = session.getId();//将浏览器中Session基于的Cookie覆盖Cookie cookie = new Cookie("JSESSIONID",sessionId);cookie.setPath("/SessionTest");cookie.setMaxAge(30*60);response.addCookie(cookie);session.setAttribute("name","洗衣机");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}

Demo2.java不变。将首页改为index.html

<!DOCTYPE html><html>  <head>    <title>index.html</title>    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">    <meta http-equiv="description" content="this is my page">    <meta http-equiv="content-type" content="text/html; charset=UTF-8">        <!--<link rel="stylesheet" type="text/css" href="./styles.css">-->  </head>    <body>    <a href="/SessionTest/servlet/Demo1">购买</a></br>    <a href="/SessionTest/servlet/Demo2">结账</a></br>  </body></html>

实现四：当用户浏览器设置为禁用cookie时，也可以实现“购买”、“结账”。

Demo1.java和Demo2.java不变，添加WelcomeServlet.java

package SessionDemo;import java.io.IOException;import java.io.PrintWriter;import javax.servlet.ServletException;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;public class WelcomeServlet extends HttpServlet{public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{//解决中文乱码问题request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=UTF-8");  PrintWriter out = response.getWriter();  request.getSession();String url1 = response.encodeURL("/SessionTest/servlet/Demo1");String url2 = response.encodeURL("/SessionTest/servlet/Demo2");out.print("<a href='"+url1+"'>购买</a></br>");out.print("<a href='"+url2+"'>结账</a></br>");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException{doGet(request, response);}}

在浏览器中将cookie禁用，加载WelcomeServlet.java,可看到（注意地址栏变化）

点击“购买”后，再点击“结账”

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