Simple Shopping System
People often go online to get enough, so the so-called shopping cart on the Internet should not be unfamiliar, so today we use the MVC design mode of javaweb to implement a case of online shopping system.
The results are as follows:
A brief introduction to the three-tier architecture
1. Development Steps
First figure out what you want to do, then:
1. Set up development environment
jstl.jar
standard.jar
2. Create Class Packages
3. Set up a database
Use in-memory database
In summary, the implementation of this shopping cart uses MVC design mode, the idea of MVC design mode is to display from jsp--javabean-servlet--jsp page
Flow chart:
Figure 1: Introduction to MVC design pattern
Figure 2: Implementing ideas for shopping system cases:
Figure 3: Design the shopping cart page
The Festival Officially begins, and you can't miss it.
1. Write a jsp shopping page
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <% String path = request.getContextPath(); String basePath = request.getScheme() + "://" + request.getServerName() + ":" + request.getServerPort() + path + "/"; %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <title>Piaoye Online Shop</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <hr/> <h2 >Welcome to Drifting Leaf Online Shopping Mall</h2> <hr> <a href="${pageContext.request.contextPath}/ListBookServlet">Go to shopping page</a> <br> </body> </html>
2. Write a javabean
package cn.itcast.cart.domain; public class Book { private String id; private String name;//Title private String author;//author private int price; public Book() { super(); // TODO Auto-generated constructor stub } public Book(String id, String name, String author, int price) { super(); this.id = id; this.name = name; this.author = author; this.price = price; } 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 int getPrice() { return price; } public void setPrice(int price) { this.price = price; } }
3. Set up a DB to simulate a database with a Map collection
package cn.itcast.cart.domain; import java.util.Collection; import java.util.LinkedHashMap; import java.util.Map; public class DB { // Use map Collection to simulate database private static Map<String , Book> books=new LinkedHashMap<String, Book>(); static{ books.put("1", new Book("1", "<Water Margin", "Shi Nai'an", 48)); books.put("2", new Book("2", "<Journey to the West", "Wu Cheng-en ", 58)); books.put("3", new Book("3", "<The Romance of the Three Kingdoms", "Luo Guanzhong", 78)); books.put("4", new Book("4", "<Dream of Red Mansion", "Cao Xueqin", 28)); books.put("5", new Book("5", "<Ordinary World", "Rotel", 18)); } // Get all books // Get all books public static Collection<Book> getAll() { return books.values(); } // according to id Find Books public static Book find(String id) { return books.get(id); } }
4. Create a shopping cart object with javabean
package cn.itcast.cart.domain; public class ShoppingcartItem { //Shopping cart items, how many books each book has bought, how much is the total money private Book book; private int quantity; private int 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; this.price=this.book.getPrice()*quantity; } public int getPrice() { return price; } public void setPrice(int price) { this.price = price; } }
Shopping cart - cart
package cn.itcast.cart.domain; import java.util.HashMap; import java.util.Map; //Shopping Cart Objects public class Shoppingcart { private Map<String, ShoppingcartItem> items=new HashMap<String, ShoppingcartItem>(); private int price;//Total Price public Map<String, ShoppingcartItem> getItems() { return items; } public void setItems(Map<String, ShoppingcartItem> items) { this.items = items; } public int getPrice() { //Calculate total price int price=0; for(ShoppingcartItem item:items.values()) { price+=item.getPrice(); } return price; } public void setPrice(int price) { this.price = price; } }
5. Obtain a servlet for a list of book merchandises-ListBookServlet.java
package cn.itcast.cart.web.servlet; import java.io.IOException; import java.util.Collection; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import cn.itcast.cart.domain.Book; import cn.itcast.cart.domain.DB; public class ListBookServlet extends HttpServlet { //from DB Query all books in public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //Query all items Collection<Book> books = DB.getAll(); // Forward to jsp display request.setAttribute("books", books); request.getRequestDispatcher("/WEB-INF/pages/listbook.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
6. The data handled by the servlet is forwarded to a page showing the goods-listbook.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %> <!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>Show all items</title> <script type="text/javascript"> function buy(id){ window.location = "${pageContext.request.contextPath}/BuyServlet?id="+id; } </script> </head> <body style="text-align: center"> <h1 >List of Goods</h1> <table border="1" width="400px"> <tr> <td>Book Name</td> <td>author</td> <td>Price</td> <td>purchase</td> </tr> <c:forEach var="book" items="${requestScope.books}"> <tr> <td>${book.name}</td> <td>${book.author}</td> <td>${book.price}</td> <td> <input type="button" value="purchase" onclick="buy(${book.id})"/> </td> </tr> </c:forEach> </table> </body> </html>
7. Write a servlet for purchase processing
package cn.itcast.cart.web.servlet; 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.cart.domain.Book; import cn.itcast.cart.domain.DB; import cn.itcast.cart.domain.Shoppingcart; import cn.itcast.cart.domain.ShoppingcartItem; public class BuyServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //Purchase Page //Get Books String id=request.getParameter("id"); Book book=DB.find(id); // Get a shopping cart Shoppingcart cart = (Shoppingcart) request.getSession().getAttribute("cart"); if(cart==null){ //First time shopping cart=new Shoppingcart(); request.getSession().setAttribute("cart", cart); } // Goods in shopping cart bookInCart(book,cart); // Jump to the shopping cart page,Is a page requesting redirection response.sendRedirect(request.getContextPath()+"/ListCartServlet"); } //Shopping private void bookInCart(Book book, Shoppingcart cart) {//Determine if you have ever bought Map<String, ShoppingcartItem> items = cart.getItems(); ShoppingcartItem item = items.get(book.getId()); if(item==null){ //This book has not been bought, create a new entry item=new ShoppingcartItem(); item.setBook(book); item.setQuantity(1); //Entries are stored in the shopping cart items.put(book.getId(), item); }else{ //Buied quantity plus 1 item.setQuantity(item.getQuantity()+1); } } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
8. Write a servlet to get data processing from the shopping cart-ListCartServlet.java
package cn.itcast.cart.web.servlet; import java.io.IOException; import javax.servlet.ServletException; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; public class ListCartServlet extends HttpServlet { //View the shopping cart, request redirection page public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.getRequestDispatcher("/WEB-INF/pages/listcart.jsp").forward(request, response); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
9. Put your purchases in the shopping cart and turn to the shopping cart display page-listcart.jsp
<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%> <%-- As long as you use foreach To import this code--%> <%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%> <!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>Shopping Cart Page</title> <script type="text/javascript"> function change(id,inputObj){ var quantity=inputObj.value; if(quantity==null || quantity=="") { alert("Quantity cannot be empty"); inputObj.value = defaultValue; return; } if(quantity.match(/^[1-9][0-9]*$/)==null) { alert("Quantity must be a positive integer"); inputObj.value = defaultValue; return; } if(parseInt(quantity)>999) { alert("The quantity you have purchased has reached the group purchase standard, please call 800-820-8820"); inputObj.value = defaultValue; return; } window.location="${pageContext.request.contextPath}/UpdateServlet?id="+id+"&quantity="+quantity; } </script> </head> <body style="text-align: center"> <h1>My shopping cart</h1><br> <hr> <table border="1" width="800px"> <tr> <td>Commodity Name</td> <td>Unit Price</td> <td>Number</td> <td>Subtotal</td> <td>operation</td> </tr> <%--map After iteration, all entry--%> <c:forEach var="entry" items="${cart.items}"> <tr> <td>${entry.value.book.name}</td> <td>${entry.value.book.price}</td> <td> <input type="text" value="${entry.value.quantity}" onblur="change(${entry.key},this) " style="width: 40px;"/> </td> <td>${entry.value.price}</td> <td> <a href="${pageContext.request.contextPath}/DaleServlet?id=${entry.key }">delete</a> </td> </tr> </c:forEach> <tr> <td> <a href="${pageContext.request.contextPath}/clearServlet">empty cart</a> </td> <td> <a href="${pageContext.request.contextPath}/ListBookServlet">Continue shopping</a> </td> <td> <a href="#">Place an order</a> </td> <td colspan="2">Total Shopping Cart Price:￥${cart.price}element</td> </tr> </table> </body> </html>
Here are some of the operation functions inside the shopping cart
10. Updating the shopping cart means automatically updating the shopping cart after modifying the quantity-UpdateServlet.java
package cn.itcast.cart.web.servlet; 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.cart.domain.Shoppingcart; import cn.itcast.cart.domain.ShoppingcartItem; public class UpdateServlet extends HttpServlet { //Update shopping cart public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { //Get id and quantity String id=request.getParameter("id"); int quantity=Integer.parseInt(request.getParameter("quantity")); //Get a shopping cart Shoppingcart cart = (Shoppingcart) request.getSession().getAttribute("cart"); // Modified Quantity /* Map<String, ShoppingcartItem> items = cart.getItems(); ShoppingcartItem item = items.get(id); item.setQuantity(quantity);*/ cart.getItems().get(id).setQuantity(quantity); // Jump to the shopping cart page response.sendRedirect(request.getContextPath() + "/ListCartServlet"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
11. Delete one-line data from the shopping cart -DaleServlet.java
package cn.itcast.cart.web.servlet; 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.cart.domain.Shoppingcart; public class DaleServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Get id String id = request.getParameter("id"); // Get a shopping cart Shoppingcart cart = (Shoppingcart) request.getSession().getAttribute("cart"); //Delete entries cart.getItems().remove(id); // Jump to the shopping cart page response.sendRedirect(request.getContextPath()+"/ListCartServlet"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
12. Empty the shopping cart-clearServlet.java
package cn.itcast.cart.web.servlet; 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.cart.domain.Shoppingcart; public class clearServlet extends HttpServlet { public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // Get a shopping cart Shoppingcart cart = (Shoppingcart) request.getSession().getAttribute("cart"); // empty cart cart.getItems().clear(); // Jump to the purchase page response.sendRedirect(request.getContextPath()+"/ListBookServlet"); } public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
ok, busy till midnight, that's the end. Let's see what we're doing in the end:
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Hey hey, no artistic pages, okay, like that?
All the above functions can be achieved!
