前面用户验证成功以后跳转到hall.jsp,展示商品
hall.jsp
<%@ page language="java" import="java.util.*,com.wxh.domain.*" 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 style="text-align:center; margin:0 auto; ">
<h1>欢迎来到购物大厅</h1>
<table border="1"style="border-collapse: collapse; width: 500px" align="center">
<tr><th>书名</th><th>价格</th><th>出版社</th><th>点击购买</th></tr>
<%
//取出request中的那个Araylist
ArrayList al=(ArrayList)request.getAttribute("books");
for(int i=0;i<al.size();i++){
Book book=(Book)al.get(i);
%>
<tr><td><%=book.getName()%></td><td><%=book.getPrice() %></td><td><%=book.getPublishHouse() %></td>
<td>
<a href="/shopping/ShoppingClServlet?type=add&id=<%=book.getId()%>" >点击购买</a>
</td>
</tr>
<%
}
%>
<tr align="center"><td colspan="4"><input type="button" value="查看购物车" onclick="window.location.href='/shopping/ShoppingClServlet?type=show';"></td></tr>
</table>
<hr/>
<a href="/shopping/">返回重新登录</a>
</body>
</html>
在GoHallUI中已经给下一个页面hall.jsp准备要了显示的数据
调用了BookService类
首先
Book.java
package com.wxh.domain;
public class Book {
private int id;
private String name;
private String publishHouse;
private double price;
private int nums; //该书的库存
private int shoppingNum=1; //购买的数量
private String author;
public int getShoppingNum() {
return shoppingNum;
}
public void setShoppingNum(int shoppingNum) {
this.shoppingNum = shoppingNum;
}
public String getAuthor() {
return author;
}
public void setAuthor(String author) {
this.author = author;
}
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPublishHouse() {
return publishHouse;
}
public void setPublishHouse(String publishHouse) {
this.publishHouse = publishHouse;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
public int getNums() {
return nums;
}
public void setNums(int nums) {
this.nums = nums;
}
}
BookService.java
package com.wxh.service;
import java.util.ArrayList;
import com.wxh.domain.Book;
import com.wxh.utils.SqlHelper;
//这是一个业务逻辑类，用于处理与book表相关的业务，各司其职
public class BookService {
//根据书的编号，返回一个Book
public Book getBookById(String id){
Book book=new Book();
String sql="select * from book where id=?";
String paras[]={id};
ArrayList al=new SqlHelper().executeQuery(sql, paras);
if(al.size()==1){
Object[] obj=(Object[])al.get(0);
book.setId(Integer.parseInt(obj[0].toString()));
book.setName(obj[1].toString());
book.setAuthor(obj[2].toString());
book.setPublishHouse(obj[3].toString());
book.setPrice(Float.parseFloat(obj[4].toString()));
book.setNums(Integer.parseInt(obj[5].toString()));
}
return book;
}
//得到所有的书籍信息（分页）
public ArrayList getAllBook(){
String sql="select * from book where 1=?";
String paras[]={"1"};
ArrayList al=new SqlHelper().executeQuery(sql, paras);
ArrayList<Book> newAl=new ArrayList<Book>();
//二次业务封装
for(int i=0;i<al.size();i++){
Object obj[]=(Object[])al.get(i);
Book book=new Book();
book.setId(Integer.parseInt(obj[0].toString()));
book.setName(obj[1].toString());
book.setAuthor(obj[2].toString());
book.setPublishHouse(obj[3].toString());
book.setPrice(Float.parseFloat(obj[4].toString()));
book.setNums(Integer.parseInt(obj[5].toString()));
newAl.add(book);
}
return newAl;
}
}
购买功能的实现
在GOHallUI中已经创建了一个购物车
MyCart.java
package com.wxh.service;
import java.util.*;
import com.wxh.domain.Book;
//这个表示我的购物车
public class MyCart {
HashMap<String,Book> hm=new HashMap<String,Book>();
//添加书的第二个方法
public void addBook2(String id){
if(hm.containsKey(id)){
//hm已经有这个书
Book book=hm.get(id);
int shoppingNum=book.getShoppingNum();
book.setShoppingNum(shoppingNum+1);
}else{
hm.put(id, new BookService().getBookById(id));
}
}
//返回该购物车的总价格
public float getTotalPrice(){
float totalPrice=0.0f;
//得到总价格
ArrayList<Book> al=new ArrayList<Book>();
Iterator it=hm.keySet().iterator();
while(it.hasNext()){
//取出书号
String bookId=(String)it.next();
//取出书号对应的Book
Book book=hm.get(bookId);
totalPrice+=book.getPrice()*book.getShoppingNum();
}
return totalPrice;
}
//添加书籍
public void addBook(String id,Book book){
if(hm.containsKey(id)){
book=hm.get(id);
//如果这本书已经购买过，shoppingNum数量+1
int shoppingNum=book.getShoppingNum();
book.setShoppingNum(shoppingNum+1);
//hm.put(id, book);
}else{
hm.put(id, book);
}
}
//删除书籍
public void delBook(String id){
hm.remove(id);
}
//更新书籍(对于购物车，更新所买书籍的数量)
public void updateBook(String id,String nums){
//取出id对应的Book
Book book=hm.get(id);
book.setShoppingNum(Integer.parseInt(nums));
}
//显示该购物车中的所有商品信息
public ArrayList showMyCart(){
ArrayList<Book> al=new ArrayList<Book>();
//遍历HashMap
Iterator it=hm.keySet().iterator();
while(it.hasNext()){
//取出key
String id=(String)it.next();
//取出Book
Book book=hm.get(id);
al.add(book);
}
return al;
}
//清空书,清空购物车
public void clearBook(){
hm.clear();
}
}
当点击 点击购买 链接时 提交给ShoppingClServlet处理
ShoppingClServlet.java
//该控制器处理用户购买商品的请求
public class ShoppingClServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
PrintWriter out = response.getWriter();
//接收type值，区分用户希望做什么，del，update，add
String type=request.getParameter("type");
if(type.equals("del")){
//说明用户要删除商品
//接收用户想购买的商品的id
String id=request.getParameter("id");
//得到购物车(从session中取得购物车)
MyCart myCart=(MyCart)request.getSession().getAttribute("myCart");
myCart.delBook(id);
//把要显示的商品信息放入request
request.setAttribute("bookList", myCart.showMyCart());
//跳回showMyCart.jsp
request.getRequestDispatcher("/WEB-INF/showMyCart.jsp").forward(request, response);
}else if(type.equals("add")){
//接收用户想购买的商品的id
String id=request.getParameter("id");
System.out.println(id);
//什么时候创建购物车对象（当用户登录成功后，为他创建一个购物车）
//取出购物车，并添加书到购物车中
MyCart myCart=(MyCart)request.getSession().getAttribute("myCart");
//相当于把商品加到购物车
myCart.addBook2(id);
/*
//把要显示的数据放入request，准备显示。
request.setAttribute("bookList", myCart.showMyCart());
request.setAttribute("totalPrice", myCart.getTotalPrice()+"");
//跳转到显示我的购物车去
request.getRequestDispatcher("/WEB-INF/showMyCart.jsp").forward(request, response);
*/
//为了防止某个页面刷新，我们可以用sendredirect（）
response.sendRedirect("/shopping/GoShowMyCart");
}else if(type.equals("update")){
//更新
//判断有没有书籍
//得到用户希望更新的书号和数量
String bookIds[]=request.getParameterValues("id");
//得到每本书的数量
String nums[]=request.getParameterValues("booknum");
MyCart myCart=(MyCart)request.getSession().getAttribute("myCart");
for(int i=0;i<bookIds.length;i++){
//更新购物车
myCart.updateBook(bookIds[i], nums[i]);
}
//跳转回我的购物车
//把要显示的数据放入request，准备显示。
request.setAttribute("bookList", myCart.showMyCart());
request.setAttribute("totalPrice", myCart.getTotalPrice()+"");
//跳转到显示我的购物车去
request.getRequestDispatcher("/WEB-INF/showMyCart.jsp").forward(request, response);
}
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
————摘自《韩顺平细说jsp》
时间： 2024-08-28 02:22:51