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 }