【期末大作业】使用Python熟练掌握面向对象

引言

在编程学习过程中，构建项目是一个非常有效的方式，不仅能巩固和应用所学的知识，还能通过实践来解决实际问题。本文将通过几个经典的项目示例来展示如何用面向对象的方式设计和实现一个完整的系统，包括学生成绩管理系统、图书馆管理系统、电子商务网站模拟以及猜数字游戏。通过这些项目，你将能够掌握如何运用面向对象设计原则来处理数据存储、异常处理、系统功能模块化等常见问题，从而为更复杂的应用程序开发打下坚实的基础。

学生成绩管理系统

下面是学生管理系统的简单功能，其余几个类似，这里不做一一展示

这个学生成绩管理系统实现了以下功能：
添加学生信息
录入学生成绩
查询单个学生的成绩信息
查看某科目的班级平均分
数据持久化（保存到CSV文件）
系统的特点：
使用面向对象设计，将学生和管理系统分别封装
实现了异常处理，确保输入数据的正确性
使用CSV文件进行数据存储
提供了友好的命令行界面

首先创建主要的类和文件结构：

class Student:def __init__(self, student_id, name):self.student_id = student_idself.name = nameself.scores = {}  # 科目: 分数def add_score(self, subject, score):self.scores[subject] = scoredef get_average(self):if not self.scores:return 0return sum(self.scores.values()) / len(self.scores)

import csv
import osclass StudentManager:def __init__(self):self.students = {}  # student_id: Student对象self.file_path = "ts.csv"self.load_data()def add_student(self, student):self.students[student.student_id] = studentdef get_student(self, student_id):return self.students.get(student_id)def add_score(self, student_id, subject, score):if student_id in self.students:self.students[student_id].add_score(subject, score)def get_class_average(self, subject):scores = [s.scores.get(subject, 0) for s in self.students.values() if subject in s.scores]if not scores:return 0return sum(scores) / len(scores)def save_to_csv(self):with open(self.file_path, 'w', newline='', encoding='utf-8') as f:writer = csv.writer(f)writer.writerow(['学号', '姓名', '科目', '分数'])for student in self.students.values():for subject, score in student.scores.items():writer.writerow([student.student_id, student.name, subject, score])def load_data(self):if not os.path.exists(self.file_path):returnwith open(self.file_path, 'r', encoding='utf-8') as f:reader = csv.reader(f)next(reader)  # 跳过表头for row in reader:student_id, name, subject, score = rowif student_id not in self.students:self.students[student_id] = Student(student_id, name)self.students[student_id].add_score(subject, float(score))

# -*- coding: utf-8 -*-
rom student import Student
rom student_manager import StudentManager
def main():manager = StudentManager()while True:print("\n=== 学生成绩管理系统 ===")print("1. 添加学生")print("2. 录入成绩")print("3. 查询学生成绩")print("4. 查看班级平均分")print("5. 保存并退出")choice = input("请选择操作 (1-5): ").strip()if choice == '1':student_id = input("请输入学号: ").strip()name = input("请输入姓名: ").strip()student = Student(student_id, name)manager.add_student(student)print("学生添加成功！")elif choice == '2':student_id = input("请输入学号: ").strip()subject = input("请输入科目: ").strip()try:score = float(input("请输入分数: ").strip())manager.add_score(student_id, subject, score)print("成绩录入成功！")except ValueError:print("分数输入错误！请输入有效的数字。")elif choice == '3':student_id = input("请输入要查询的学号: ").strip()student = manager.get_student(student_id)if student:print(f"\n学号：{student.student_id}")print(f"姓名：{student.name}")print("成绩：")for subject, score in student.scores.items():print(f"{subject}: {score}")print(f"平均分：{student.get_average():.2f}")else:print("未找到该学生！")elif choice == '4':subject = input("请输入要查询的科目: ").strip()avg = manager.get_class_average(subject)print(f"{subject}的班级平均分是：{avg:.2f}")elif choice == '5':manager.save_to_csv()print("数据已保存，程序退出！")breakelse:print("无效的选择，请重试！")
if __name__ == "__main__":main()

界面如下

图书馆管理系统

class Book:def __init__(self, book_id, title,author):self.book_id = book_idself.title = titleself.author = authorself.is_borrowed = Falseself.borrow_history = []  # 借阅历史记录def borrow(self, user_id, borrow_date):if not self.is_borrowed:self.is_borrowed = Trueself.borrow_history.append({'user_id': user_id,'borrow_date': borrow_date,'return_date': None})return Truereturn Falsedef return_book(self, return_date):if self.is_borrowed:self.is_borrowed = Falseself.borrow_history[-1]['return_date'] = return_datereturn Truereturn False

class User:def __init__(self, user_id, name):self.user_id = user_idself.name = nameself.borrowed_books = []  # 当前借阅的图书ID列表     def borrow_book(self, book_id):self.borrowed_books.append(book_id)def return_book(self, book_id):if book_id in self.borrowed_books:self.borrowed_books.remove(book_id)return Truereturn False

import json
import datetime
from book import Book
from user import Userclass Library:def __init__(self):self.books = {}  # book_id: Book对象self.users = {}  # user_id: User对象self.load_data()def add_book(self, book):self.books[book.book_id] =  def add_user(self, user):self.users[user.user_id] = userdef borrow_book(self, user_id, book_id):if user_id not in self.users or book_id not in self.books:return Falsebook = self.books[book_id]user = self.users[user_id]if book.borrow(user_id, datetime.datetime.now()):user.borrow_book(book_id)return Truereturn Falsedef return_book(self, user_id, book_id):if user_id not in self.users or book_id not in self.books:return Falsebook = self.books[book_id]user = self.users[user_id]if book.return_book(datetime.datetime.now()):user.return_book(book_id)return Truereturn Falsedef save_data(self):data = {'books': {bid: {'title': book.title,'author': book.author,'is_borrowed': book.is_borrowed,'borrow_history': book.borrow_history} for bid, book in self.books.items()},'users': {uid: {'name': user.name,'borrowed_books': user.borrowed_books} for uid, user in self.users.items()}}with open('library_data.json', 'w', encoding='utf-8') as f:json.dump(data, f, ensure_ascii=False, default=str)def load_data(self):try:with open('library_data.json', 'r', encoding='utf-8') as f:data = json.load(f)for book_id, book_data in data['books'].items():book = Book(book_id, book_data['title'], book_data['author'])book.is_borrowed = book_data['is_borrowed']book.borrow_history = book_data['borrow_history']self.books[book_id] = bookfor user_id, user_data in data['users'].items():user = User(user_id, user_data['name'])user.borrowed_books = user_data['borrowed_books']self.users[user_id] = userexcept FileNotFoundError:pass

界面如下

电子商务网站模拟

class Product:def __init__(self, product_id, name, price, stock):self.product_id = product_idself.name = nameself.price = priceself.stock = stockdef decrease_stock(self, quantity):if self.stock >= quantity:self.stock -= quantityreturn Truereturn False

class ShoppingCart:def __init__(self):self.items = {}  # product_id: quantitydef add_item(self, product_id, quantity):if product_id in self.items:self.items[product_id] += quantityelse:self.items[product_id] = quantitydef remove_item(self, product_id):if product_id in self.items:del self.items[product_id]def update_quantity(self, product_id, quantity):if quantity <= 0:self.remove_item(product_id)else:self.items[product_id] = quantitydef get_total(self, products):total = 0for product_id, quantity in self.items.items():if product_id in products:total += products[product_id].price * quantityreturn total

import datetimeclass Order:def __init__(self, order_id, user_id, items, total_amount):self.order_id = order_idself.user_id = user_idself.items = items  # {product_id: quantity}self.total_amount = total_amountself.order_date = datetime.datetime.now()self.status = "pending"  # pending, paid, delivereddef pay(self):self.status = "paid"def ship(self):self.status = "shipped"def deliver(self):self.status = "delivered"

import json
from product import Product
from cart import ShoppingCart
from order import Orderclass Store:def __init__(self):self.products = {}  # product_id: Product对象self.orders = {}    # order_id: Order对象self.load_data()def add_product(self, product):self.products[product.product_id] = productdef create_order(self, user_id, cart):order_id = str(len(self.orders) + 1)total = cart.get_total(self.products)# 检查库存for product_id, quantity in cart.items.items():if not self.products[product_id].decrease_stock(quantity):return Noneorder = Order(order_id, user_id, cart.items.copy(), total)self.orders[order_id] = orderreturn orderdef save_data(self):data = {'products': {pid: {'name': p.name,'price': p.price,'stock': p.stock} for pid, p in self.products.items()},'orders': {oid: {'user_id': o.o.items,'total_amount': o.total_amount,'order_date': str(o.order_date),'status': o.status} for oid, o in self.orders.items()}}with open('store_data.json', 'w', encoding='utf-8') as f:json.dump(data, f, ensure_ascii=False)def load_data(self):try:with open('store_data.json', 'r', encoding='utf-8') as f:data = json.load(f)for pid, p_data in data['products'].items():self.products[pid] = Product(pid, p_data['name'], p_data['price'], p_data['stock'])for oid, o_data in data['orders'].items():self.orders[oid] = Order(oid, o_data['user_id'], o_data['items'],o_data['total_amount'])self.orders[oid].status = o_data['status']except FileNotFoundError:pass

from store import Store
from product import Product
from cart import ShoppingCartdef main():store = Store()cart = ShoppingCart()    while True:print("\n电子商务系统")print("1. 添加商品")print("2. 查看商品列表")print("3. 添加到购物车")print("4. 查看购物车")print("5. 修改购物车")print("6. 创建订单")print("7. 查看订单")print("8. 保存并退出")choice = input("请选择操作 (1-8): ")if choice == '1':product_id = input("请输入商品ID: ")name = input("请输入商品名称: ")try:price = float(input("请输入价格: "))stock = int(input("请输入库存数量: "))product = Product(product_id, name, price, stock)store.add_product(product)print("商品添加成功！")except ValueError:print("输入错误！")elif choice == '2':print("\n商品列表：")for pid, product in store.products.items():print(f"ID: {pid}")print(f"名称: {product.name}")print(f"价格: ￥{product.price:.2f}")print(f"库存: {product.stock}")print()elif choice == '3':product_id = input("请输入商品ID: ")if product_id in store.products:try:quantity = int(input("请输入数量: "))if quantity > 0:cart.add_item(product_id, quantity)print("添加成功！")else:print("数量必须大于0！")except ValueError:print("输入错误！")else:print("商品不存在！")elif choice == '4':print("\n购物车：")total = 0for pid, quantity in cart.items.items():if pid in store.products:product = store.products[pid]subtotal = product.price * quantitytotal += subtotalprint(f"商品: {product.name}")print(f"数量: {quantity}")print(f"小计: ￥{subtotal:.2f}")print()print(f"总计: ￥{total:.2f}")elif choice == '5':product_id = input("请输入要修改的商品ID: ")if product_id in cart.items:try:quantity = int(input("请输入新的数量(0表示删除): "))cart.update_quantity(product_id, quantity)print("修改成功！")except ValueError:print("输入错误！")else:print("购物车中没有该商品！")elif choice == '6':if not cart.items:print("购物车为空！")continueuser_id = input("请输入用户ID: ")order = store.create_order(user_id, cart)if order:print(f"订单创建成功！订单号：{order.order_id}")cart = ShoppingCart()  # 清空购物车else:print("订单创建失败！库存不足")elif choice == '7':print("\n订单列表：")for oid, order in store.orders.items():print(f"订单号: {oid}")print(f"用户ID: {order.user_id}")print(f"总金额: ￥{order.total_amount:.2f}")print(f"状态: {order.status}")print("商品:")for pid, quantity in order.items.items():if pid in store.products:print(f"- {store.products[pid].name} x {quantity}")print()elif choice == '8':store.save_data()print("数据已保存，程序退出！")breakelse:print("无效的选择，请重试！")
if __name__ == "__main__":main()

界面如下

猜数字游戏

import random
import json
from datetime import datetimeclass NumberGame:def __init__(self):self.target = 0self.max_tries = 10self.high_scores = []self.load_scores()def start_new_game(self):self.target = random.randint(1, 100)return self.targetdef check_guess(self, guess):if guess < self.target:return "太低了"elif guess > self.target:return "太高了"else:return "猜对了"def add_score(self, player_name, tries):score = {'player': player_name,'tries': tries,'date': datetime.now().strftime("%Y-%m-%d %H:%M:%S")}self.high_scores.append(score)self.high_scores.sort(key=lambda x: x['tries'])self.high_scores = self.high_scores[:10]  # 只保留前10名self.save_scores()def save_scores(self):with open('high_scores.json', 'w', encoding='utf-8') as f:json.dump(self.high_scores, f, ensure_ascii=False)def load_scores(self):try:with open('high_scores.json', 'r', encoding='utf-8') as f:self.high_scores = json.load(f)except FileNotFoundError:self.high_scores = []

from game import NumberGamedef main():game = NumberGame()while True:print("\n猜数字游戏")print("1. 开始新游戏")print("2. 查看排行榜")print("3. 退出")choice = input("请选择操作 (1-3): ")if choice == '1':game.start_new_game()tries = 0print(f"\n游戏开始！你有{game.max_tries}次机会猜一个1-100之间的数。")while tries < game.max_tries:ry:guess = int(input(f"还剩{game.max_tries - tries}次机会，请猜一个数: "))tries += 1if guess < 1 or guess > 100:print("请猜1-100之间的数！")continueresult = game.check_guess(guess)print(result)if result == "猜对了":print(f"恭喜你用了{tries}次猜对了！")name = input("请输入你的名字记录成绩: ")game.add_score(name, tries)breakexcept ValueError:print("请输入有效的数字！")if tries >= game.max_tries:print(f"游戏结束！正确答案是{game.target}")elif choice == '2':print("\n排行榜：")for i, score in enumerate(game.high_scores, 1):print(f"{i}. {score['player']}: {score['tries']}次 ({score['date']})")elif choice == '3':print("谢谢游戏，再见！")breakelse:print("无效的选择，请重试！")
if __name__ == "__main__":main()

界面如下

结语

本文展示的几个项目涵盖了日常生活中常见的管理和游戏系统，旨在帮助读者更好地理解如何运用Python进行面向对象的编程实践。每个项目都涉及到不同的功能模块与实际问题，通过这些示例，你可以学到如何设计易于维护的代码结构，如何处理用户输入、数据存储以及程序的整体逻辑。无论你是初学者还是有一定基础的开发者，这些项目都能为你提供一定的编程经验和思维方式，帮助你在未来的编程道路上更加自信地面对挑战。希望你能从这些项目中获得启发，并将所学应用到更多实际的编程任务中！

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