JSP
JSP三种脚本元素
EL表达式(获取域中的数据)
Cookie
记录最新访问时间，获得cookie中上次访问时间，显示浏览器页面上
商品浏览记录案例
Session
验证码登录案例
购物车案例
持久Session案例(Session的JSESSIONID保存到Cookie中)
------------------------------------------------------------------
在做练习的时候:
有些字段是不能小写的,例如:JSESSIONID.
输出HTML标签时,<a>标签少打了个 ' 导致页面无显示内容,但源码中有内容
JSP
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <h1>Hello JSP</h1> <%=new java.util.Date().toLocaleString() %> </body> </html>
JSP三种脚本元素
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <h1>学习JSP三种脚本元素</h1> <!-- JSP 声明脚本, 会被翻译为 Servlet成员变量、方法 --> <%! int a = 10; class A { // 内部类 } %> <!-- JSP 脚本表达式 ,输出HTML源代码 , 不能以 ;结尾 --> <%="aaa"+"bbb" %> <%="<h1>Hello</h1>" %> <!-- JSP脚本代码中 嵌入任意java代码 --> <% for(int i =0 ;i <10 ;i++){ // 输出i 到浏览器 out.print(i); } %> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <% // 可以嵌入任意java代码， 由多个 % 共同组成一段java代码， 脚本片段可以断开 for(int i = 0;i < 10 ;i++){ %> <h1>两个脚本片段中间可以编写HTML代码</h1> <% } %> </body> </html>
EL表达式(获取域中的数据)
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <!-- ServletContext 允许将一个数据保存到ServletContext ,这个数据全局数据，可以被多个Servlet共享 --> <!-- HttpServletRequest 允许将一个数据 保存 request对象中，通过请求转发，将数据传递另一个Servlet --> <% // 将数据 保存ServletContext中 getServletContext().setAttribute("name","传智播客"); // 将数据 保存request中 request.setAttribute("address","北京"); %> <!-- 取出上面保存两个值，输出浏览器端 --> <%=getServletContext().getAttribute("name") %> <%=request.getAttribute("address") %> <!-- 通过EL表达式 取出 name和address的值 --> ${ applicationScope.name} ${requestScope.address } <hr/> <!-- 访问一个不存在的属性 --> 传统%方式 ： <%=request.getAttribute("city") %> <br/> EL方式： ${requestScope.city } <br/> </body> </html>
Cookie
记录最新访问时间，获得cookie中上次访问时间，显示浏览器页面上
package cn.itcast.cookie; import java.io.IOException; import java.util.Date; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 记录最新访问时间，获得cookie中上次访问时间，显示浏览器页面上 * * @author seawind * */ public class VisitServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 判断是否存在cookie 信息 Cookie[] cookies = request.getCookies(); // 获得所有cookie信息 // 在cookies 数组中查找指定名称cookie Cookie lastVisitCookie = findCookie(cookies, "lastvisit"); if (lastVisitCookie == null) { // 不存在上次访问时间 response.setContentType("text/html;charset=utf-8"); response.getWriter().println("欢迎第一次访问XXX网站！"); } else { // 存在上次访问时间 long lastvisittimes = Long.parseLong(lastVisitCookie.getValue()); // 假设保存时间是毫秒 response.setContentType("text/html;charset=utf-8"); response.getWriter().println( "您上次的访问时间是：" + new Date(lastvisittimes).toLocaleString()); } // 向客户端写回最新访问时间 Cookie newLastVisitCookie = new Cookie("lastvisit", System .currentTimeMillis() + ""); newLastVisitCookie.setMaxAge(60 * 60);// 保存cookie 1小时 newLastVisitCookie.setPath("/"); response.addCookie(newLastVisitCookie); } // Cookie格式========== Cookie: name=value,name=value,name=value // 客户端对于同一个网站会存在很多个cookie private Cookie findCookie(Cookie[] cookies, String name) { if (cookies == null) { // 不存在任何cookie return null; } else { // 存在cookie，查找指定cookie for (Cookie cookie : cookies) { if (cookie.getName().equals(name)) { // 找到了 return cookie; } } // 没有找到 return null; } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
商品浏览记录案例
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@page import="cn.itcast.utils.CookieUtils"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <!-- 商品列表 --> <h1>商品列表</h1> <a href="/day7/show?id=1">Java编程大全</a> <a href="/day7/show?id=2">MYSQL秘笈</a> <a href="/day7/show?id=3">设计模式入门</a> <a href="/day7/show?id=4">数据结构和算法</a> <a href="/day7/show?id=5">软件工程</a> <a href="/day7/show?id=6">面向对象程序设计</a> <!-- 浏览记录 --> <h1>浏览记录</h1> <h2><a href="/day7/clear">清空记录</a></h2> <% // 获得history对应商品编号 Cookie historyCookie = CookieUtils.findCookie(request.getCookies(),"history"); if(historyCookie == null){ // 没有浏览记录 out.println("<h2>无任何商品浏览记录！</h2>"); }else{ // 有浏览记录 String value = historyCookie.getValue(); String[] ids = value.split(","); String[] names = {"Java编程大全","MYSQL秘笈","设计模式入门","数据结构和算法","软件工程","面向对象程序设计"}; for(String id : ids){ out.println(names[Integer.parseInt(id)-1]+"<br/>"); } } %> </body> </html>
package cn.itcast.cookie; import java.io.IOException; 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 cn.itcast.utils.CookieUtils; /** * 查看商品信息，将浏览记录 保存到cookie 中 * * @author seawind * */ public class ShowProductServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 从请求参数中 获得商品 id String id = request.getParameter("id"); // 获得history 对应cookie信息 Cookie historyCookie = CookieUtils.findCookie(request.getCookies(), "history"); // 判断historyCookie是否存在 if (historyCookie == null) { // 不存在，这是浏览的第一个商品 Cookie cookie = new Cookie("history", id); cookie.setMaxAge(60 * 60 * 24 * 14);// 两个星期 cookie.setPath("/"); response.addCookie(cookie); } else { // 商品浏览记录已经存在 // 判断该商品是否已经在浏览记录中，如果在 String value = historyCookie.getValue(); String[] ids = value.split(","); if (!checkExist(ids, id)) { // 7,8 +,+ 3 Cookie cookie = new Cookie("history", value + "," + id); cookie.setMaxAge(60 * 60 * 24 * 14);// 两个星期 cookie.setPath("/"); response.addCookie(cookie); } } response.setContentType("text/html;charset=utf-8"); response.getWriter().println( "商品浏览成功！<a href='/day7/cookie/product.jsp'>返回 </a>"); } // 判断商品编号 是否已经存在 浏览记录中 private boolean checkExist(String[] ids, String id) { for (String eachId : ids) { if (eachId.equals(id)) { // id已经存在 return true; } } return false; } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package cn.itcast.cookie; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.Cookie; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 删除 history 持久cookie * * @author seawind * */ public class ClearServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Cookie cookie = new Cookie("history", ""); cookie.setMaxAge(0); cookie.setPath("/"); response.addCookie(cookie); response.sendRedirect("/day7/cookie/product.jsp"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package cn.itcast.utils; import javax.servlet.http.Cookie; public class CookieUtils { // 根据name 查找指定cookie public static Cookie findCookie(Cookie[] cookies, String name) { if (cookies == null) { // 不存在任何cookie return null; } else { // 存在cookie，查找指定cookie for (Cookie cookie : cookies) { if (cookie.getName().equals(name)) { // 找到了 return cookie; } } // 没有找到 return null; } } }
Session
验证码登录案例
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <h1>登陆后 欢迎页面</h1> <% String username = (String)request.getSession().getAttribute("username"); if(username == null){ // 未登陆 out.println("您还未登陆，<a href='/day7/session/login.jsp'>去登陆</a>"); }else{ // 已经登陆 out.println("欢迎您，"+username); } %> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> <script type="text/javascript"> function change(){ document.getElementById("myimg").src = "/day7/checkimg?"+new Date().getTime(); } </script> </head> <body> <h1>登陆页面</h1> <h2 style="color:red;">${requestScope.msg }</h2> <form action="/day7/login" method="post"> <table> <tr> <td>用户名</td> <td><input type="text" name="username" /></td> </tr> <tr> <td>密码</td> <td><input type="password" name="password"/> </td> </tr> <tr> <td>验证码</td> <td><input type="text" name="checkcode" /> <img src="/day7/checkimg" onclick="change();" id="myimg" style="cursor: pointer;"/></td> </tr> <tr> <td colspan="2"><input type="submit" value="登陆" /></td> </tr> </table> </form> </body> </html>
package cn.itcast.session; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 进行登陆操作 * * @author seawind * */ public class LoginServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获得用户名、密码和 验证码 request.setCharacterEncoding("utf-8"); String username = request.getParameter("username"); String password = request.getParameter("password"); String checkcode = request.getParameter("checkcode"); // 判断验证码是否正确 String checkcode_session = (String) request.getSession().getAttribute( "checkcode_session"); request.getSession().removeAttribute("checkcode_session"); if (checkcode_session == null || !checkcode_session.equals(checkcode)) { // 验证码输入错误 // 重定向跳回 login.jsp 无法携带信息，转发可以 request.setAttribute("msg", "验证码输入错误！"); request.getRequestDispatcher("/session/login.jsp").forward(request, response); return; } // 判断用户名和密码是否正确 ，假设用户名和密码都是admin/admin if ("admin".equals(username) && "admin".equals(password)) { // 登陆成功 // 将登陆信息保存session request.getSession().setAttribute("username", username); response.sendRedirect("/day7/session/welcome.jsp"); } else { // 登陆失败 request.setAttribute("msg", "用户名或者密码错误！"); request.getRequestDispatcher("/session/login.jsp").forward(request, response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package cn.itcast.session; import java.awt.Color; import java.awt.Font; import java.awt.Graphics; import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.IOException; import java.util.Random; import javax.imageio.ImageIO; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; /** * 生成验证码图片 * * @author seawind * */ public class CheckImgServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 禁止缓存 // response.setHeader("Cache-Control", "no-cache"); // response.setHeader("Pragma", "no-cache"); // response.setDateHeader("Expires", -1); int width = 120; int height = 30; // 步骤一 绘制一张内存中图片 BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB); // 步骤二 图片绘制背景颜色 ---通过绘图对象 Graphics graphics = bufferedImage.getGraphics();// 得到画图对象 --- 画笔 // 绘制任何图形之前 都必须指定一个颜色 graphics.setColor(getRandColor(200, 250)); graphics.fillRect(0, 0, width, height); // 步骤三 绘制边框 graphics.setColor(Color.WHITE); graphics.drawRect(0, 0, width - 1, height - 1); // 步骤四 四个随机数字 Graphics2D graphics2d = (Graphics2D) graphics; // 设置输出字体 graphics2d.setFont(new Font("宋体", Font.BOLD, 18)); // String words = // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890"; String words = "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"; Random random = new Random();// 生成随机数 // 为了将验证码保存Session StringBuffer buffer = new StringBuffer(); // 定义x坐标 int x = 10; for (int i = 0; i < 4; i++) { // 随机颜色 graphics2d.setColor(new Color(20 + random.nextInt(110), 20 + random .nextInt(110), 20 + random.nextInt(110))); // 旋转 -30 --- 30度 int jiaodu = random.nextInt(60) - 30; // 换算弧度 double theta = jiaodu * Math.PI / 180; // 生成一个随机数字 int index = random.nextInt(words.length()); // 生成随机数 0 到 length - 1 // 获得字母数字 char c = words.charAt(index); // 将生成汉字 加入buffer buffer.append(c); // 将c 输出到图片 graphics2d.rotate(theta, x, 20); graphics2d.drawString(String.valueOf(c), x, 20); graphics2d.rotate(-theta, x, 20); x += 30; } // 将验证码内容保存session request.getSession().setAttribute("checkcode_session", buffer.toString()); // 步骤五 绘制干扰线 graphics.setColor(getRandColor(160, 200)); int x1; int x2; int y1; int y2; for (int i = 0; i < 30; i++) { x1 = random.nextInt(width); x2 = random.nextInt(12); y1 = random.nextInt(height); y2 = random.nextInt(12); graphics.drawLine(x1, y1, x1 + x2, x2 + y2); } // 将上面图片输出到浏览器 ImageIO graphics.dispose();// 释放资源 ImageIO.write(bufferedImage, "jpg", response.getOutputStream()); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } /** * 取其某一范围的color * * @param fc * int 范围参数1 * @param bc * int 范围参数2 * @return Color */ private Color getRandColor(int fc, int bc) { // 取其随机颜色 Random random = new Random(); if (fc > 255) { fc = 255; } if (bc > 255) { bc = 255; } int r = fc + random.nextInt(bc - fc); int g = fc + random.nextInt(bc - fc); int b = fc + random.nextInt(bc - fc); return new Color(r, g, b); } }
购物车案例
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <!-- 商品列表页面 --> <h1>商品列表</h1> <h2><a href="/day7/session/cart.jsp">查看购物车</a></h2> Java编程大全 <a href="/day7/buy?id=1">购买</a> <br/> MySQL秘笈 <a href="/day7/buy?id=2">购买</a> <br/> 设计模式入门 <a href="/day7/buy?id=3">购买</a> <br/> 软件工程模式 <a href="/day7/buy?id=4">购买</a> <br/> 敏捷开发 <a href="/day7/buy?id=5">购买</a> <br/> 项目管理精要 <a href="/day7/buy?id=6">购买</a> <br/> </body> </html>
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%@page import="java.util.Map"%> <%@page import="java.util.Set"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>Insert title here</title> </head> <body> <!-- 显示Session中保存 购物车数据 --> <% Map<String,Integer> map = (Map<String,Integer>)request.getSession().getAttribute("cart"); if(map == null){ // 购物车对象不存在 out.println("<h2>购物车无任何商品信息！</h2>"); }else{ // 购物车对象已经存在 out.println("<h1>商品列表</h1>"); out.println("<a href='/day7/clearCart'>清空购物车</a><br/>"); Set<String> keySet = map.keySet(); for(String productName: keySet){ int number = map.get(productName);// 购买数量 out.println("商品名称： " + productName +", 购买数量：" + number + "<br/>"); } } %> </body> </html>
package cn.itcast.session; import java.io.IOException; import java.util.HashMap; import java.util.Map; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * 添加商品到购物车 * * @author seawind * */ public class BuyServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获得购买商品 id String id = request.getParameter("id"); // 获得id 对应商品名称 String[] names = { "Java编程入门", "MySQL秘笈", "设计模式入门", "软件工程模式", "敏捷开发", "项目管理精要" }; String productName = names[Integer.parseInt(id) - 1]; // 判断Session中购物车是否存在 HttpSession session = request.getSession(); Map<String, Integer> cart = (Map<String, Integer>) session .getAttribute("cart"); if (cart == null) { // 购物车不存在 cart = new HashMap<String, Integer>(); } // 判断购买商品是否存在于购物车中，商品名称就是map的key if (cart.containsKey(productName)) { // 商品已经在购物车中 int number = cart.get(productName);// 取出原来数量 cart.put(productName, number + 1);// 数量+1 放回购物车 } else { // 商品不在购物车中 cart.put(productName, 1);// 保存商品到购物车，数量为1 } // 将购物车对象保存Session session.setAttribute("cart", cart); // 给用户提示 response.setContentType("text/html;charset=utf-8"); response.getWriter().println( "商品已经添加到购物车！<a href='/day7/session/product.jsp'>返回</a>"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package cn.itcast.session; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * 清空购物车 * * @author seawind * */ public class ClearCartServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 删除购物车 cart对象 HttpSession session = request.getSession(); // 删除购物车cart对象 session.removeAttribute("cart"); // 跳转cart.jsp response.sendRedirect("/day7/session/cart.jsp"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
持久Session案例(Session的JSESSIONID保存到Cookie中)
package cn.itcast.session; import java.io.IOException; 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; /** * 第一次访问 创建Session对象，将数据保存到Session中 * * @author seawind * */ public class SessionServlet1 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 第一次访问，创建新的Session对象 HttpSession session = request.getSession(); // 将jsessionid 写到持久cookie中 Cookie cookie = new Cookie("JSESSIONID", session.getId()); cookie.setMaxAge(60 * 60 * 24); cookie.setPath("/"); response.addCookie(cookie); // 保存数据到Session session.setAttribute("name", "冰箱"); // 生成链接 --- 使用URL重写 String url = "/day7/session2";// 拼jsessionid url = response.encodeURL(url); response.getWriter().println("<a href='" + url + "'>session2</a>"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
package cn.itcast.session; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import javax.servlet.http.HttpSession; /** * 从Session读取 已经保存信息 显示到浏览器上 * * @author seawind * */ public class SessionServlet2 extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获得Session对象，因为不是第一次访问，获得之前已经存在Session HttpSession session = request.getSession(); // 获得之前保存name数据 String name = (String) session.getAttribute("name"); // 显示浏览器上 response.setContentType("text/html;charset=utf-8"); response.getWriter().println("name:" + name); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <servlet> <servlet-name>HelloServlet</servlet-name> <servlet-class>cn.itcast.servlet.HelloServlet</servlet-class> </servlet> <servlet> <servlet-name>VisitServlet</servlet-name> <servlet-class>cn.itcast.cookie.VisitServlet</servlet-class> </servlet> <servlet> <servlet-name>ShowProductServlet</servlet-name> <servlet-class>cn.itcast.cookie.ShowProductServlet</servlet-class> </servlet> <servlet> <servlet-name>ClearServlet</servlet-name> <servlet-class>cn.itcast.cookie.ClearServlet</servlet-class> </servlet> <servlet> <servlet-name>SessionServlet1</servlet-name> <servlet-class>cn.itcast.session.SessionServlet1</servlet-class> </servlet> <servlet> <servlet-name>SessionServlet2</servlet-name> <servlet-class>cn.itcast.session.SessionServlet2</servlet-class> </servlet> <servlet> <servlet-name>BuyServlet</servlet-name> <servlet-class>cn.itcast.session.BuyServlet</servlet-class> </servlet> <servlet> <servlet-name>ClearCartServlet</servlet-name> <servlet-class>cn.itcast.session.ClearCartServlet</servlet-class> </servlet> <servlet> <servlet-name>CheckImgServlet</servlet-name> <servlet-class>cn.itcast.session.CheckImgServlet</servlet-class> </servlet> <servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.itcast.session.LoginServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>HelloServlet</servlet-name> <url-pattern>/hello</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>VisitServlet</servlet-name> <url-pattern>/visit</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>ShowProductServlet</servlet-name> <url-pattern>/show</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>ClearServlet</servlet-name> <url-pattern>/clear</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>SessionServlet1</servlet-name> <url-pattern>/session1</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>SessionServlet2</servlet-name> <url-pattern>/session2</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>BuyServlet</servlet-name> <url-pattern>/buy</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>ClearCartServlet</servlet-name> <url-pattern>/clearCart</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>CheckImgServlet</servlet-name> <url-pattern>/checkimg</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>LoginServlet</servlet-name> <url-pattern>/login</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>