servlet-cookie和session应用示例：模拟购物车
思路分析：1.根据需求抽象出业务对象
User{
usrename;
password;
}
ShoppingCarItem{
product;
num;
}
ShoppingCar{
List<ShoppingCarItem>
}
2. 写Servlet处理请求
...
domain:
package cn.itcast.cd.domain;import java.util.ArrayList;import java.util.List;import java.util.UUID;public class ShoppingCar {private List<ShoppingCarItem> list = new ArrayList<ShoppingCarItem>();/** * 根据货品和数量往购物车中添加 * @param product * @param num */public void add(String product,Integer num){ShoppingCarItem carItem = new ShoppingCarItem();carItem.setNum(num);carItem.setProduct(product);carItem.setId(UUID.randomUUID().toString());list.add(carItem);}/** * 根据唯一的标示删除购物车中对应的明细 * @param id */public void remove(String id){for (ShoppingCarItem item : list) { if(id.equals(item.getId())){ list.remove(item); break; }}}public List<ShoppingCarItem> getList() {return list;}}package cn.itcast.cd.domain;public class ShoppingCarItem {private String product;private Integernum;private String id;//给每一个明细生成一个唯一的idpublic String getProduct() {return product;}public void setProduct(String product) {this.product = product;}public Integer getNum() {return num;}public void setNum(Integer num) {this.num = num;}public String getId() {return id;}public void setId(String id) {this.id = id;}}package cn.itcast.cd.domain;public class User {private String username;private String password;public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}}
servlet:
package cn.itcast.cd.servlet;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;import cn.itcast.cd.domain.ShoppingCar;public class BuyServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=utf-8"); //1.获取请求中的参数.String product = request.getParameter("product");String num = request.getParameter("num"); //2. 获取到购物车 //2.1首先要到session中找一下是否已经有了购物车. 如果有的话就不需要创建了... 直接把货品放到购物车中就可以了HttpSession httpSession = request.getSession();ShoppingCar shoppingCar = (ShoppingCar)httpSession.getAttribute("SHOPINGCAR_IN_SESSION");if(shoppingCar==null){ //说明是第一次购物. 还没有购物车的//2.2如果从session中没有找到购物车. 需要新创建一个购物车并且放到session中.为了下次购物使用这个购物车shoppingCar = new ShoppingCar();httpSession.setAttribute("SHOPINGCAR_IN_SESSION", shoppingCar);}shoppingCar.add(product, Integer.parseInt(num));PrintWriter pw = response.getWriter();pw.println("添加成功<br/>");pw.println("<a href='/buy.html'>继续购物</a><br/>");pw.println("<a href='/list'>管理购物</a><br/>");}}package cn.itcast.cd.servlet;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;import cn.itcast.cd.domain.ShoppingCar;import cn.itcast.cd.domain.ShoppingCarItem;import cn.itcast.cd.domain.User;public class ListServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=utf-8");HttpSession httpSession = request.getSession();//1. 先获取session中的User User user= (User) httpSession.getAttribute("USER_IN_SESSION"); PrintWriter pw = response.getWriter(); pw.println("当前用户为:"+user.getUsername()+"<br/>");//2. 获取session的购物车 ShoppingCar shoppingCar = (ShoppingCar) httpSession.getAttribute("SHOPINGCAR_IN_SESSION"); //2.1如果在session中购物车的话,列出购物车中的明细 if(shoppingCar!=null){ for (ShoppingCarItem item : shoppingCar.getList()) { pw.println("货品:"+item.getProduct()+"数量:"+item.getNum()+"<br/>"); } }else{ //2.2 在session中没有购物车的话.提示用户没有当前用户名购物车 pw.println("当前用户没有购物车."); }}}package cn.itcast.cd.servlet;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;import cn.itcast.cd.domain.User;public class LoginServlet extends HttpServlet {@Overrideprotected void service(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {request.setCharacterEncoding("UTF-8");response.setContentType("text/html;charset=utf-8");//1. 接收请求中的数据封装对象String username = request.getParameter("username");String password = request.getParameter("password");User user = new User();user.setPassword(password);user.setUsername(username);//2. 将用户方到session中供ListServlet从session中访问到UserHttpSessionhttpSession = request.getSession();httpSession.setAttribute("USER_IN_SESSION", user);PrintWriter pw = response.getWriter();pw.println("欢迎:"+username+"<br/>");pw.println("<a href='/buy.html'>购物</a><br/>");pw.println("<a href='/list'>管理购物</a><br/>");}}
用户登录页面：
<!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>用户登录</title></head><body><form action="/login" method="post">用户名：<input type="text" name="username"><br/>密码：<input type="text" name="password"><br/><input type="submit" value="登录"></form></body></html>
购买页面：
<!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>购物货品</title></head><body><form action="/buy" method="post">货品：<select name="product"><option value="鼠标">鼠标</option><option value="键盘">键盘</option><option value="内存">内存</option> <option value="显示器">显示器</option></select><br/>数量：<input type="text" name="num"><br/><input type="submit" value="购买"></form></body></html>
web.xml配置：
<?xml version="1.0" encoding="UTF-8"?><web-app 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" version="2.5"><servlet> <servlet-name>LoginServlet</servlet-name> <servlet-class>cn.itcast.cd.servlet.LoginServlet</servlet-class> </servlet> <servlet-mapping><servlet-name>LoginServlet</servlet-name><url-pattern>/login</url-pattern></servlet-mapping> <servlet> <servlet-name>BuyServlet</servlet-name> <servlet-class>cn.itcast.cd.servlet.BuyServlet</servlet-class> </servlet> <servlet-mapping><servlet-name>BuyServlet</servlet-name><url-pattern>/buy</url-pattern></servlet-mapping> <servlet> <servlet-name>ListServlet</servlet-name> <servlet-class>cn.itcast.cd.servlet.ListServlet</servlet-class> </servlet> <servlet-mapping><servlet-name>ListServlet</servlet-name><url-pattern>/list</url-pattern></servlet-mapping></web-app>
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