【案例3-1】基于控制台的购书系统
【案例介绍】
伴随互联网的蓬勃发展,网络购书系统作为电子商务的一种形式,正以其高效、低成本的优势逐步成为新兴的经营模式,人们已经不再满足互联网的用途仅仅局限于信息的浏览和发布,更渴望着能够充分享受互联网所带来的更多便利。网络购书系统正适应了当今社会快节奏地生活,使顾客足不出户便可以方便快捷轻松地选购自己喜欢的图书。
本任务要求,使用所学知识编写一个基于控制台的购书系统,实现购书功能。
- 输出所有图书的信息:包括每本书的编号、书名、单价、库存。
- 顾客购买书时,根据提示输入图书编号来选购需要的书,并根据提示输入购买书的的数量。
- 购买完毕后输出顾客的订单信息,包括:订单号、订单明细、订单总额。
【分析】
(1)通过任务描述可知,该系统中必须包括3个实体类,类名及属性设置如下:
- 图书类(Book):
a) 图书编号(id)
b) 图书名称(name)
c) 图书单价(price)
d) 库存数量(storage) - 订单项类(OrderItem):
a) 图书(book)
b) 购买数量(num) - 订单类(Order):
a) 订单号(orderID)
b) 订单总额(total)
c) 订单项列表(items)
(2)由于购买图书时,需要选择图书的数量,所以需要在订单项类里定义获取图书对象以及图书数量的方法。
(3)由于需要指定订单项以及获取订单的订单列表、订单号、订单总额等信息,所以需要有订单列表、订单号、订单总额指定订单项等方法。
【代码】
Book.java
package com.j2se.myInstances.example3_1;
public class Book {
private int bno;
private String bid;
private String name;
private double price;
private int stocks;
public Book(int bno, String bid, String name, double price, int stocks) {
this.bno = bno;
this.bid = bid;
this.name = name;
this.price = price;
this.stocks = stocks;
}
public int getBno() {
return bno;
}
public String getBid() {
return bid;
}
public String getName() {
return name;
}
public double getPrice() {
return price;
}
public int getStocks() {
return stocks;
}
}
OrderItem.java
package com.j2se.myInstances.example3_1;
public class OrderItem {
private Book book;
private int nums;
public OrderItem(Book book, int nums) {
this.book = book;
this.nums = nums;
}
public Book getBook() {
return book;
}
public int getNums() {
return nums;
}
public void setBook(Book book) {
this.book = book;
}
public void setNums(int nums) {
this.nums = nums;
}
}
Order.java
package com.j2se.myInstances.example3_1;
public class Order {
private String oid;
private OrderItem[] items;
private double total;
public Order(String oid) {
this.oid = oid;
this.items = new OrderItem[3];
}
public String getOid() {
return oid;
}
public void setOid(String oid) {
this.oid = oid;
}
public OrderItem[] getItems() {
return items;
}
public void setItems(OrderItem item, int idx) {
this.items[idx] = item;
}
public double getTotal() {
calcTotal();
return total;
}
private void calcTotal() {
double total = 0;
for (int i = 0; i < items.length; ++i) {
total += items[i].getNums() * items[i].getBook().getPrice();
}
this.total = total;
}
public void setTotal(double total) {
this.total = total;
}
}
BookDemo.java
package com.j2se.myInstances.example3_1;
import java.time.LocalTime;
import java.util.Scanner;
public class BookDemo {
public static void main(String[] args) {
Book[] books = new Book[3]; // 存储图书
outBookInfo(books);
// 购买图书
Order order = purchase(books);
// 打印订单
outOrderInfo(order);
}
private static void outOrderInfo(Order order) {
System.out.println("-------------------\t图书订单\t--------------------");
System.out.println("订单编号:" + order.getOid());
System.out.println("\t图书名称\t\t购买数量\t图书单价");
OrderItem[] items = order.getItems();
String line = null;
for (int i = 0; i < items.length; ++i) {
line = items[i].getBook().getName() + "\t" + items[i].getNums() + "\t" + items[i].getBook().getPrice();
System.out.println(line);
}
System.out.println("订单总额:¥" + order.getTotal());
System.out.println("------------------------------------------------");
}
private static Order purchase(Book[] books) {
Scanner sc = new Scanner(System.in);
OrderItem item = null;
Order order = new Order("book-order-" + LocalTime.now().toString());
for (int i = 0; i < books.length; i++) {
System.out.print("请选择需要购买的图书编号:");
int bno = sc.nextInt();
System.out.print("购买数量:");
int num = sc.nextInt();
item = new OrderItem(books[bno - 1], num);
order.setItems(item, i);
System.out.println("请继续购买图书。");
}
sc.close();
return order;
}
private static void outBookInfo(Book[] books) {
books[0] = new Book(1, "b978-7-115-548", "Java基础案例编程", 19.9, 100);
books[1] = new Book(2, "b328-3-124-431", "Python数据分析", 29.9, 56);
books[2] = new Book(3, "b112-8-765-904", "机器学习实战(上)", 39.9, 220);
System.out.println("-------------------\t图书列表\t--------------------");
System.out.println("编号\t\tISBN\t\t\t名称\t\t\t价格\t\t库存");
String line = null;
for (int i = 0; i < books.length; i++) {
line = books[i].getBno() + "\t" + books[i].getBid() + "\t" + books[i].getName() + "\t" + books[i].getPrice()
+ "\t" + books[i].getStocks();
System.out.println(line);
}
System.out.println("------------------------------------------------");
}
}