三层架构模式(MVC)案例:购物车实现
1.搭建开发环境
1.1 导开发包
jstl开发包
1.2 建立程序开发包
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2、开发实体
2.1 创建封装实体的Javabean,
2.1.1Book.java
public class Book { private String id; private String name; private String author; private double price; private String description; public Book() { super(); // TODO Auto-generated constructor stub } public Book(String id, String name, String author, double price, String description) { super(); this.id = id; this.name = name; this.author = author; this.price = price; this.description = description; } 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 String getAuthor() { return author; } public void setAuthor(String author) { this.author = author; } public double getPrice() { return price; } public void setPrice(double price) { this.price = price; } public String getDescription() { return description; } public void setDescription(String description) { this.description = description; } }
2.1.1购物车Cart对象,Cart.java
import java.util.LinkedHashMap; import java.util.Map; //代表购物车 public class Cart { //用于保存购物车中所有商品 private Map<String,CartItem> map = new LinkedHashMap(); private double price; //0 public void add(Book book){ //javaweb CartItem item = map.get(book.getId()); if(item!=null){ item.setQuantity(item.getQuantity()+1); }else{ item = new CartItem(); item.setBook(book); item.setQuantity(1); map.put(book.getId(), item); } } public Map<String, CartItem> getMap() { return map; } public void setMap(Map<String, CartItem> map) { this.map = map; } public double getPrice() { double totalprice = 0; for(Map.Entry<String,CartItem> me : map.entrySet()){ CartItem item = me.getValue(); totalprice += item.getPrice(); } return totalprice; } public void setPrice(double price) { this.price = price; } }
2.1.3CartItem.java 完成购买哪本书,购买数量 功能
//cartItem代表某本书，并表示书出现多少次 public class CartItem { private Book book; private int quantity; private double price; public Book getBook() { return book; } public void setBook(Book book) { this.book = book; } public int getQuantity() { return quantity; } public void setQuantity(int quantity) { this.quantity = quantity; } public double getPrice() { return book.getPrice()*this.quantity; } public void setPrice(double price) { this.price = price; } }
2.2 创建一个类模拟数据库MyDb.java
import java.util.LinkedHashMap; import java.util.Map; import cn.itcast.domain.Book; //模似数据库 public class MyDb { private static Map<String,Book> map = new LinkedHashMap(); static{ map.put("1", new Book("1","javaweb开发","老张",20,"一本经典的书")); map.put("2", new Book("2","jdbc开发","李勇",30,"一本jdbc的书")); map.put("3", new Book("3","spring开发","老黎",50,"一本相当经典的书")); map.put("4", new Book("4","hibernate开发","老佟",56,"一本佟佟的书")); map.put("5", new Book("5","struts开发","老毕",40,"一本经典的书")); map.put("6", new Book("6","ajax开发","老张",50,"一本老张的书")); } public static Map getAll(){ return map; } }
2.3 实现Dao类,获取数据库数据BookDao.java
import java.util.Map; import cn.itcast.db.MyDb; import cn.itcast.domain.Book; public class BookDao { public Map getAll(){ return MyDb.getAll(); } public Book find(String id){ return (Book) MyDb.getAll().get(id); } }
3,开发Service 层
3.1开发BusinessService.java完成业务处理功能
package cn.itcast.service; import java.util.Map; import cn.itcast.dao.BookDao; import cn.itcast.domain.Book; import cn.itcast.domain.Cart; import cn.itcast.domain.CartItem; import cn.itcast.exception.CartNotFoundException; public class BusinessService { BookDao dao = new BookDao(); //列出所有书的服务 public Map getAllBook(){ return dao.getAll(); } public void buybook(String bookid, Cart cart) { Book book = dao.find(bookid); cart.add(book); } public void deleteBook(String bookid, Cart cart) throws CartNotFoundException { if(cart==null){ throw new CartNotFoundException("购物车为空！！"); } Map map = cart.getMap(); map.remove(bookid); } public void clearCart(Cart cart) throws CartNotFoundException { if(cart==null){ throw new CartNotFoundException("购物车为空！！"); } cart.getMap().clear(); } public void updateCart(Cart cart, String bookid, int quantity) throws CartNotFoundException { if(cart==null){ throw new CartNotFoundException("购物车为空！！"); } CartItem item = cart.getMap().get(bookid); item.setQuantity(quantity); } }
3.2 开发自定义异常类 CartNotFoundException.java
package cn.itcast.exception; public class CartNotFoundException extends Exception { public CartNotFoundException() { // TODO Auto-generated constructor stub } public CartNotFoundException(String message) { super(message); // TODO Auto-generated constructor stub } public CartNotFoundException(Throwable cause) { super(cause); // TODO Auto-generated constructor stub } public CartNotFoundException(String message, Throwable cause) { super(message, cause); // TODO Auto-generated constructor stub } }
4,Web层开发Servlet与用户界面层
4.1 实现购买功能的Servlet :BuyServlet.java
package cn.itcast.web.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.domain.Cart; import cn.itcast.service.BusinessService; //完成购买操作 public class BuyServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String bookid = request.getParameter("bookid"); //把用户买的书加到购物车中 Cart cart = (Cart) request.getSession().getAttribute("cart"); if(cart==null){ cart = new Cart(); request.getSession().setAttribute("cart", cart); } BusinessService service = new BusinessService(); service.buybook(bookid,cart); request.getRequestDispatcher("/WEB-INF/jsp/listcart.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
4.2 实现清空购物车Servlet:ClearCartServlet.java
package cn.itcast.web.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.domain.Cart; import cn.itcast.exception.CartNotFoundException; import cn.itcast.service.BusinessService; public class ClearCartServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { Cart cart = (Cart) request.getSession().getAttribute("cart"); BusinessService service = new BusinessService(); try { service.clearCart(cart); request.getRequestDispatcher("/WEB-INF/jsp/listcart.jsp").forward(request, response); } catch (CartNotFoundException e) { request.setAttribute("message", "对不起，您还没有购买任何商品!!!"); request.getRequestDispatcher("/message.jsp").forward(request, response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
4.3 删除购买书的Servlet:DeleteServlet.java
package cn.itcast.web.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.domain.Cart; import cn.itcast.exception.CartNotFoundException; import cn.itcast.service.BusinessService; public class DeleteServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String bookid = request.getParameter("bookid"); Cart cart = (Cart) request.getSession().getAttribute("cart"); BusinessService service = new BusinessService(); try { service.deleteBook(bookid,cart); request.getRequestDispatcher("/WEB-INF/jsp/listcart.jsp").forward(request, response); } catch (CartNotFoundException e) { request.setAttribute("message", "对不起，您还没有购买任何商品!!!"); request.getRequestDispatcher("/message.jsp").forward(request, response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
4.4 实现购买首页书本列表Servlet;ListBookServlet.java
package cn.itcast.web.controller; import java.io.IOException; import java.util.Map; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.service.BusinessService; //列出所有书 public class ListBookServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { BusinessService service = new BusinessService(); Map map = service.getAllBook(); request.setAttribute("map", map); request.getRequestDispatcher("/WEB-INF/jsp/listbook.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
4.5 更新修改购买书本数量Servlet: UpdateCartServlet.java
package cn.itcast.web.controller; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.domain.Cart; import cn.itcast.exception.CartNotFoundException; import cn.itcast.service.BusinessService; public class UpdateCartServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String bookid = request.getParameter("bookid"); int quantity = Integer.parseInt(request.getParameter("quantity")); Cart cart = (Cart) request.getSession().getAttribute("cart"); BusinessService service = new BusinessService(); try { service.updateCart(cart,bookid,quantity); request.getRequestDispatcher("/WEB-INF/jsp/listcart.jsp").forward(request, response); } catch (CartNotFoundException e) { request.setAttribute("message", "对不起，您还没有购买任何商品!!!"); request.getRequestDispatcher("/message.jsp").forward(request, response); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
5. 购物车JSP显示页面
5.1 listbook.jsp 用到jstl.jar
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>为 JSTL 中导入标签库的taglib导入,这个需要注意,不能忘记!!
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>书籍列表页面</title> </head> <body style="text-align: center;"> <br/> <h2>书籍列表</h2> <br/><br/> <table border="1" width="80%"> <tr> <td>书籍编号</td> <td>书名</td> <td>作者</td> <td>售价</td> <td>描述</td> <td>操作</td> </tr> <%-- Set<Map.Entry<String,Book>> --%> <c:forEach var="me" items="${map}"> <tr> <td>${me.key }</td> <td>${me.value.name }</td> <td>${me.value.author }</td> <td>${me.value.price }</td> <td>${me.value.description }</td> <td> <a href="${pageContext.request.contextPath }/servlet/BuyServlet?bookid=${me.key }">购买</a> </td> </tr> </c:forEach> </table> </body> </html>
5.2 listcart.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>My JSP 'listcart.jsp' starting page</title> <script type="text/javascript"> function clearcart(){ var b = window.confirm("您确定要清空购物车吗？？"); if(b){ window.location.href="${pageContext.request.contextPath}/servlet/ClearCartServlet"; } } function updateCart(input,id,oldvalue){ var quantity = input.value; //alert(quantity); if(quantity.match(/^[0-9]*[1-9][0-9]*$/)){ var b = window.confirm("请确认改为：" + quantity); if(b){ window.location.href="${pageContext.request.contextPath}/servlet/UpdateCartServlet?bookid="+id + "&quantity=" + quantity; }else{ input.value=oldvalue; //发现用户取消的话，把input输入值改为原始值 } }else{ alert("请输入正确购买数量"); input.value=oldvalue; } } </script> </head> <body style="text-align: center;"> <br/> <h2>购物车列表</h2> <br/><br/> <c:if test="${!empty(cart.map)}"> <table border="1" width="80%"> <tr> <td>书名</td> <td>作者</td> <td>单价</td> <td>数量</td> <td>小计</td> <td>操作</td> </tr> <c:forEach var="me" items="${cart.map }"> <tr> <td>${me.value.book.name }</td> <td>${me.value.book.author }</td> <td>${me.value.book.price }</td> <td> <input type="text" name="quantity" value="${me.value.quantity }" style="width: 30px"
onchange="updateCart(this,${me.value.book.id },${me.value.quantity })"> </td> <td>${me.value.price }</td> <td> <a href="${pageContext.request.contextPath }/servlet/DeleteServlet?bookid=${me.value.book.id }">删除</a> </td> </tr> </c:forEach> <tr> <td colspan="2"> <a href="javascript:clearcart()">清空购物车</a> </td> <td colspan="2">合计</td> <td colspan="2">${cart.price }</td> </tr> </table> </c:if> <c:if test="${empty(cart.map)}"> 对不起，您还没有购买任何商品 </c:if> </body> </html>
5.3 全局消息处理页面 message.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>全局消息显示</title> </head> <body> ${message } </body> </html>
6,界面效果
ListBookServlet 首页
购物车界面
