介绍
当客户端禁用了cookie时,造成session无法访问,此时我们可以使用URL重写来解决这个问题
URL重写要求将站点中的所有超链接都进行改造,在超链接后用一个特殊的参数JSESSIONID保存当前浏览器对应session的编号,这样一来,当用户点击超链接访问服务器时,服务器可以从URL后的参数中分析出JSESSIONID,从而找到对应的sesison使用.
URL重写之前,要先创建出session,才能进行重写操作
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response.encodeURL(String url);
//--如果是普通的地址用这个方法
response.encodeRedirectURL(String url);
//--如果地址是用来进行重定向的,用这个方法
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以上两个方法可以实现URL重写,这两个方法非常的智能,只要发现浏览器发送了任何Cookie过来,就认为当前客户端没有禁用Cookie,就不会在进行URL重写
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举例：
重写URL
jsp页面
1 <%@ page language="java" import="java.util.*" pageEncoding="utf-8" session="false"%>
2 <!DOCTYPE HTML>
3 <html>
4 <head>
5 <title>My JSP 'index.jsp' starting page</title>
6 <meta http-equiv="pragma" content="no-cache">
7 <meta http-equiv="cache-control" content="no-cache">
8 <meta http-equiv="expires" content="0">
9 </head>
10 <body>
11 <h1>商品列表</h1>
12 <%
13 //在url后拼接上session的id 防止在禁用cookie时候影响session的使用
14 HttpSession session = request.getSession(); 15 String url1=response.encodeURL(request.getContextPath()+"/servlet/BuyServlet?prod=小米手机"); 16 String url2=response.encodeURL(request.getContextPath()+"/servlet/BuyServlet?prod=海尔洗衣机"); 17 String url4=response.encodeURL(request.getContextPath()+"/servlet/PayServlet"); 18
19
20
21 %>
22 <a href="<%= url1 %>">小米手机</a><br/><br/>
23 <a href="<%= url2 %>">海尔洗衣机</a><br/><br/>
24 <a href="<%= request.getContextPath() %>/servlet/BuyServlet?prod=阿迪王">阿迪王皮鞋</a><br/><br/>
25 <a href="<%= url4 %>">支付</a><br/><br/>
26 </body>
27 </html>
存入Session
servlet
1 package cn.tedu.session; 2
3 import java.io.IOException; 4
5 import javax.servlet.ServletException; 6 import javax.servlet.http.Cookie; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse; 10 import javax.servlet.http.HttpSession; 11 /** 12 * 案例:购物车 13 */
14 public class BuyServlet extends HttpServlet { 15
16 public void doGet(HttpServletRequest request, 17 HttpServletResponse response) 18 throws ServletException, IOException { 19 response.setContentType("text/html;charset=utf-8"); 20
21 //获取商品信息 控制字符集影响
22 String prod = request.getParameter("prod"); 23 byte[] bytes = prod.getBytes("iso8859-1"); 24 prod = new String(bytes, "utf-8"); 25
26 //获取session, 保存数据到session中
27 HttpSession session = request.getSession(); 28 session.setAttribute("prod", prod); 29
30 //创建一个Cookie, 这个Cookie的名字和path要和服务器创建的Cookie一样
31 Cookie cookie = new Cookie("JSESSIONID", session.getId()); 32 cookie.setPath(request.getContextPath()+"/"); 33
34 cookie.setMaxAge(3600);//设置最大生存时间为1小时
35
36 response.addCookie(cookie); 37
38 response.getWriter().write("成功将["+prod+"]商品加入了购物车..."); 39 } 40
41 public void doPost(HttpServletRequest request, 42 HttpServletResponse response) 43 throws ServletException, IOException { 44 doGet(request, response); 45 } 46
47 }
读取session
servlet
1 package cn.tedu.session; 2
3 import java.io.IOException; 4
5 import javax.servlet.ServletException; 6 import javax.servlet.http.HttpServlet; 7 import javax.servlet.http.HttpServletRequest; 8 import javax.servlet.http.HttpServletResponse; 9 import javax.servlet.http.HttpSession; 10 /** 11 * 案例:购物车 12 */
13 public class PayServlet extends HttpServlet { 14
15 public void doGet(HttpServletRequest request, 16 HttpServletResponse response) 17 throws ServletException, IOException { 18 response.setContentType("text/html;charset=utf-8"); 19
20 //获取为当前客户端服务的session, 从中取出商品信息
21 HttpSession session = request.getSession(false); 22
23 if(session != null){ 24 String prod = (String) session.getAttribute("prod"); 25 response.getWriter().write("成功为["+prod+"]商品支付10000$....."); 26 }else{ 27 response.getWriter().write("您还没有将任何商品加入购物车....."); 28 } 29 } 30
31 public void doPost(HttpServletRequest request, 32 HttpServletResponse response) 33 throws ServletException, IOException { 34 doGet(request, response); 35 } 36
37 }