session完成简单购物功能

简单购物功能"/>

session完成简单购物功能

原理：

项目目录：

Book.java代码：

package com.haidi8.book;import java.io.Serializable;public class Book implements Serializable{private String id;private String name;private double price;private String author;public Book(String id, String name, double price, String author) {super();this.id = id;this.name = name;this.price = price;this.author = author;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public String getAuthor() {return author;}public void setAuthor(String author) {this.author = author;}@Overridepublic String toString() {return "Book [id=" + id + ", name=" + name + ", price=" + price+ ", author=" + author + "]";}}

 showallbooksservlet.java代码：

package com.haidi8.car;import java.io.IOException;
import java.io.PrintWriter;
import java.util.Map;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.haidi8.book.Book;
import com.haidi8.util.DBUtil;public class showallbooksservlet extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();out.print("本网站有一下好书<br/>");Map<String, Book> books = DBUtil.findAllBooks();for (Map.Entry<String, Book> book : books.entrySet()) {String url = request.getContextPath()+"/addcar?id="+book.getKey();out.print("<a href='"+response.encodeURL(url)+"' >"+book.getValue().getName()+"</a><br/>");}String url2 = request.getContextPath()+"/showcar";out.print("<a href='"+response.encodeURL(url2)+"'>查看购物车</a>");}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}}

addcar.java代码：

package com.haidi8.car;import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;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 com.haidi8.book.Book;
import com.haidi8.util.DBUtil;public class addcar extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=UTF-8");PrintWriter out = response.getWriter();//根据ID得到书String id = request.getParameter("id");Book book=DBUtil.findBookById(id);//得到session对象HttpSession session = request.getSession();//从session中取出list(购物车）List<Book> list = (List<Book>) session.getAttribute("car");if(list==null){list=new ArrayList<Book>();}list.add(book);out.print("购买成功！");String url = request.getContextPath()+"/showallbooksservlet";response.setHeader("refresh", "2;url="+response.encodeURL(url));session.setAttribute("car", list);//把list放回session域中}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}}

showcar.java:

package com.haidi8.car;import java.io.IOException;
import java.io.PrintWriter;
import java.util.List;
import java.util.Map;import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;import com.haidi8.book.Book;public class showcar extends HttpServlet {public void doGet(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {response.setContentType("text/html;charset=utf-8");PrintWriter out = response.getWriter();out.print("购物车中有一下商品");//得到session对象List<Book> books = (List<Book>) request.getSession().getAttribute("car");if(books==null){out.print("你还没有忘购物车中添加商品");response.setHeader("refresh", "2;url="+request.getContextPath()+"/showallbooksservlet");//response.sendRedirect(request.getContextPath()+"/showallbooksservlet");}for(Book book:books){out.write(book.getName()+"<br/>");}}public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException {}}

DBUtil.java代码：

package com.haidi8.util;import java.util.HashMap;
import java.util.Map;import com.haidi8.book.Book;public class DBUtil {private static Map<String, Book> books = new HashMap<String, Book>();static{books.put("1", new Book("1", "金瓶梅", 20, "王瑞鑫"));books.put("2", new Book("2", "葵花宝典", 20, "杨成毅"));books.put("3", new Book("3", "九阴真经", 30, "陈光"));books.put("4", new Book("4", "玉女心经", 10, "陈志家"));}//得到所有书public static Map<String, Book> findAllBooks(){return books;}/*** 根据id查找指定的书* @param id* @return*/public static Book findBookById(String id){return books.get(id);}
}

web.xml代码:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" xmlns="" xmlns:xsi="" xsi:schemaLocation=" .xsd"><display-name></display-name><servlet><servlet-name>showallbooksservlet</servlet-name><servlet-class>com.haidi8.car.showallbooksservlet</servlet-class></servlet><servlet><servlet-name>addcar</servlet-name><servlet-class>com.haidi8.car.addcar</servlet-class></servlet><servlet><servlet-name>showcar</servlet-name><servlet-class>com.haidi8.car.showcar</servlet-class></servlet><servlet-mapping><servlet-name>showallbooksservlet</servlet-name><url-pattern>/showallbooksservlet</url-pattern></servlet-mapping><servlet-mapping><servlet-name>addcar</servlet-name><url-pattern>/addcar</url-pattern></servlet-mapping><servlet-mapping><servlet-name>showcar</servlet-name><url-pattern>/showcar</url-pattern></servlet-mapping>	<welcome-file-list><welcome-file>index.jsp</welcome-file></welcome-file-list>
</web-app>

运行效果：