Python 实现购物商城,含有用户入口和商家入口的示例

# Joe Young

import getpass
import os

# 调用os模块的system方法传入'cls'参数，清屏
os.system('cls') 

while True:
 entrance = input('请选择：\n\t1. 用户登陆\n\t2. 商家登陆\n>')
 if entrance != '1' and entrance != '2':
  print('\n输入有误，请重试...\n')
 else:
  break

# 打印商品列表
def print_product_list():
 index = 1
 with open('product_list.txt', 'r') as product_file:
  for product_line in product_file:
   L = [commodity, price, stock] = product_line.strip('\n').split(', ')
   commodity_list.append(L)
   print((str(index) + '. ' + commodity).ljust(20) + ('单价：' + price + '元').ljust(15) + '库存：' + stock)
   index += 1
 return

# 用户入口
if entrance == '1':

 info = []   # 存放用户的信息，初始为空
 if_payed = True # if_payed 表示订单是否已支付
 username = ''

 # 登录接口
 count = 0
 while count < 3:
  username = input('\n用户名： ')

  # 打开锁定列表文件
  with open('lock_list.txt', 'r+') as lock_file: 
   for lock_line in lock_file:
    # 用户名在锁定名单里面，则退出程序
    if username == lock_line.strip('\n'): 
     exit('\n用户名 %s 已被锁定，请联系管理员...' % username)

  login = False # 登录标志，初始为False

  # 打开用户名列表文件，读权限
  user_file = open('user_list.txt', 'r')  

  for user_line in user_file:
   # 获取每行的用户信息，用户名、密码、余额、支付密码，存入info列表
   info = [user, passwd, balance, pay_passwd] = user_line.strip('\n').split(',')
   # 用户名匹配，则进入密码输入环节
   if user == username: 
    n = 0
    # 3次输入机会
    while n < 3: 
     password = getpass.getpass('密码： ')
     # 密码匹配，显示登录成功
     if passwd == password: 
      print('\n欢迎 %s 登录商城，祝您购物愉快！\n' % username)
      login = True  # 登录标志赋值为True
      break
     # 密码不匹配
     else: 
      # n = 2 时是最后一次机会，不必提示还剩下0次机会
      if n != 2: 
       print('\n密码错误，请重新输入，您还有 %d 次机会\n' % (2-n))
     n += 1
    # 密码错误次数达到3次，锁定用户名，退出程序
    else: 
     open('lock_list.txt', 'w').write(username + '\n')
     exit('\n错误次数过多，账户已被锁定...')

    # 登录成功，跳出for循环
    if login: 
     break
  else:
   if count != 2:
    print('\n用户名不存在，请重试，您还有 %d 次机会' % (2-count))

  user_file.close()

  count += 1

  # 登录成功，跳出while循环
  if login: 
   break

 else:
  exit('\n错误次数过多，程序已退出...')

 # 购买程序
 shopping_cart = [] # 购物车初始为空
 commodity_list = []

 print_product_list()

 while True:
  i = input('\n请选择商品（输入序号），或输入 c 取消购买：')

  if i == 'c':
   while True:
    a = input('\n是否继续购买？（Y/N）:')
    if a == 'n' or a == 'N':
     exit('\n交易结束...')
    elif a == 'y' or a == 'Y':
     break
    else:
     print('\n输入格式有误，请重试...')
     continue

  if not i.isdigit():
   print('\n输入格式有误，请重试...')
   continue

  i = int(i)

  if i <= 0 or i > len(commodity_list):
   print('\n此商品不存在，请重试...')
   continue

  item_name = commodity_list[i-1][0]  # 商品名称
  item_price = commodity_list[i-1][1]  # 商品价格
  item_stock = commodity_list[i-1][2]  # 商品库存

  print('\n您已选择了 %s ，请输入购买的数量，或输入 b 重新选择：' % item_name)

  back = False

  while True:
   num = input('>')
   if num == 'b':
    back = True
    break
   if not num.isdigit():
    print('输入格式有误，请重试...')
    continue
   if int(num) > int(item_stock):
    print('数量大于库存，请重试...')
    continue
   if int(num) == 0:
    print('数量应大于0，请重试...')
   break
  if back:
   continue

  item = [item_name, item_price, num]

  print('\n您已选择了 %s，单价：%s 元，数量：%s，您想立即购买还是加入购物车？\n' % (item_name, item_price, num))
  print('\t1. 立即购买\n\t2. 加入购物车\n')

  while True:
   choice = input('>')
   if not (choice == '1' or choice == '2'):
    print('输入有误，请重试...')
    continue
   break

  user_balance = int(info[2])

  # 立即购买
  if choice == '1': 
   amount = int(item_price) * int(num)
   count = 0
   cancel = False

   while count < 3:
    user_pay_passwd = getpass.getpass('\n请输入支付密码，或输入 c 放弃支付：')
    if user_pay_passwd == 'c':
     print('\n取消支付成功...')
     cancel = True
     break
    elif user_pay_passwd != info[3]:
     if count != 2:
      print('\n密码错误，请重试，您还有 %d 次机会...' % (2-count))
     count += 1
    else:
     break

   if count == 3:
    with open('lock_list.txt', 'w') as lock_file:
     lock_file.write(username + '\n')
    exit('密码错误，账户已被锁定...')

   if cancel:
    while True:
     choice = input('\n是否继续购买？(Y/N)：')
     if not (choice == 'Y' or choice == 'y' or choice == 'N' or choice == 'n'):
      print('\n输入格式有误，请重试...')
      continue
     break
    if choice == 'Y' or choice == 'y':
     continue
    else:
     break

   # 如果用户的账户余额大于总金额
   if user_balance >= amount: 
    user_balance -= amount
    print('\n支付成功！您已成功购买 %s ，单价：%s 元，数量：%s，总金额：%s 元，账户余额：%s 元'
      % (item_name, item_price, num, amount, user_balance))
    lines = open('product_list.txt', 'r').readlines()
    # 定位到用户所购买的商品所在行，分割成列表赋值给select
    select = lines[i-1].strip('\n').split(', ')    
    # 修改商品的库存
    select[-1] = (str(int(select[-1]) - int(num)) + '\n') 
    # 拼接成字符串
    lines[i-1] = ', '.join(select)       
    # 将修改写回文件
    open('product_list.txt', 'w').writelines(lines)   

    lines = open('user_list.txt', 'r').readlines()
    # 修改用户余额
    for line in lines: 
     if username in line.split(','):  # 定位到用户名所在行
      j = lines.index(line)   # 获取用户名所在行的行号索引
      select = line.split(',')  # 分割用户名所在行赋值给列表select
      select[-2] = str(user_balance) # 修改用户余额
      lines[j] = ','.join(select)  # 修改后的列表拼接成字符串，覆盖用户名所在行
      open('user_list.txt', 'w').writelines(lines) # 将修改写回文件
   else:
    print('\n对不起，您的余额不足...')

  else: # 加入购物车
   j = 0
   for j in range(len(shopping_cart)):
    # 如果商品在购物车里面，更新商品数量
    if item_name in shopping_cart[j]: 
     shopping_cart[j][2] = str(int(shopping_cart[j][2]) + int(num))
     break
   # 商品若不在购物车，则添加到购物车
   else:
    shopping_cart.append(item) 
   print('\n成功加入购物车！')

  while True:
   choice = input('\n是否继续购买？(Y/N)：')
   if not (choice == 'Y' or choice == 'y' or choice == 'N' or choice == 'n'):
    print('\n输入格式有误，请重试...')
    continue
   break

  if choice == 'Y' or choice == 'y':
   continue
  else:
   break

 # 如果购物车不为空
 if shopping_cart: 
  print('\n您的购物车里有以下宝贝：\n')
  i = 1
  total_sum = 0
  for item in shopping_cart:
   (commodity, price, number) = (item[0], item[1], item[2])
   print((str(i) + '. ' + commodity).ljust(20) + ('单价：' + price + ' 元').ljust(15) + '数量：' + number)
   total_sum += int(price) * int(number)
   i += 1
  print('\n合计：%d 元' % total_sum)

  while True:
   if_buy = input('\n是否结算？(Y/N):')
   if not (if_buy == 'Y' or if_buy == 'y' or if_buy == 'N' or if_buy == 'n'):
    print('\n输入有误，请重试...')
    continue
   break

  while True:
   # 结算
   if if_buy == 'Y' or if_buy == 'y': 
    count = 0
    cancel = False

    while count < 3:
     user_pay_passwd = getpass.getpass('\n请输入支付密码，或输入 c 放弃支付：')
     if user_pay_passwd == 'c':
      print('\n取消支付成功...')
      cancel = True
      break
     elif user_pay_passwd != info[3]:
      if count != 2:
       print('\n密码错误，请重试，您还有 %d 次机会...' % (2-count))
      count += 1
     else:
      break

    if cancel:
     if_payed = False

    elif count == 3:
     with open('lock_list.txt', 'w') as lock_file:
      lock_file.write(username + '\n')
     exit('\n密码错误，账户已被锁定...')

    else:
     if total_sum <= user_balance:
      user_balance -= total_sum
      print('\n支付成功！您已成功购买以下商品：\n')
      i = 1
      for item in shopping_cart:
       (commodity, price, number) = (item[0], item[1], item[2])
       print((str(i) + '. ' + commodity).ljust(20) +
         ('单价：' + price + ' 元').ljust(15) + '数量：' + number)
       lines = open('product_list.txt', 'r').readlines()
       for line in lines: # 修改商品库存
        if commodity in line.split(', '):     # 定位到商品所在行
         j = lines.index(line)       # 获取商品所在行的行号索引
         select = line.split(', ')      # 商品所在行分割为字符串列表
         select[-1] = (str(int(select[-1]) - int(number)) + '\n') # 修改商品库存
         lines[j] = ', '.join(select)      # 将修改后的字符串列表组成字符串
         open('product_list.txt', 'w').writelines(lines) # 把修改写回文件
       i += 1

      lines = open('user_list.txt', 'r').readlines()

      for line in lines: # 用户余额写入文件
       if username in line.split(','):
        j = lines.index(line)
        select = line.split(',')
        select[-2] = str(user_balance)
        lines[j] = ','.join(select)
        open('user_list.txt', 'w').writelines(lines)

      exit('\n合计：%d 元， 账户余额：%d 元' % (total_sum, user_balance))

   # 不结算
   else: 
    print('\n您有一笔未支付订单...')
    while True:
     choice = input('\n是否进行支付？(Y/N):')
     if not (choice == 'Y' or choice == 'y' or choice == 'N' or choice == 'n'):
      print('\n输入有误，请重试...')
      continue
     break
    if choice == 'n' or choice == 'N':
     exit('\n订单已取消，感谢光临购物商城，再见...')
    else:
     if_buy = 'Y'
     continue

   if not if_payed:
    print('\n您有一笔未支付订单...')
    while True:
     choice = input('\n是否进行支付？(Y/N):')
     if not (choice == 'Y' or choice == 'y' or choice == 'N' or choice == 'n'):
      print('\n输入有误，请重试...')
      continue
     break

    if choice == 'n' or choice == 'N':
     exit('\n订单已取消，感谢光临购物商城，再见...')
    else:
     if_buy = 'Y'
     continue

# 商家入口
if entrance == '2':  

 seller_name = ''

 # 登录接口
 count = 0
 while count < 3:
  seller_name = input('\n用户名：')

  with open('lock_list.txt', 'r') as lock_file:
   for lock_line in lock_file:
    if seller_name == lock_line.strip('\n'):
     exit('\n用户名 %s 已被锁定，请联系管理员...' % seller_name)

  seller_file = open('seller_list.txt', 'r')
  login = False

  for seller_line in seller_file:
   (seller, passwd) = seller_line.strip('\n').split(',')
   if seller_name == seller:
    n = 0
    while n < 3:
     password = getpass.getpass('密码：')
     # 登录成功，跳出while循环
     if password == passwd:
      print('\n欢迎 %s 登录商城' % seller_name)
      login = True
      break 
     else:
      if n != 2:
       print('\n密码错误，请重试，您还有 %d 次机会' % (2-n))
     n += 1
    # n = 3，锁定用户名
    else:   
     open('lock_list.txt', 'w').write(seller_name + '\n')
     exit('\n错误次数过多，账户已被锁定...')
    # 登录成功，跳出for循环
    if login:  
     break

  # 用户名不存在
  else:  
   if count != 2:
    print('\n用户名不存在，请重试，您还有 %d 次机会' % (2-count))

  # 登录成功，跳出while循环
  if login: 
   break

  count += 1

 else:
  exit('\n错误次数过多，程序已退出...')


 # 商品列表编辑程序
 
 L = []
 # 存放商品列表，初始为空
 commodity_list = []
 index = 1

 print('\n您的货架上有以下商品：\n')
 
 print_product_list()

 while True:
  choice = input('\n是否编辑您的商品列表？(Y/N):')
  if not (choice == 'Y' or choice == 'y' or choice == 'N' or choice == 'n'):
   print('\n输入有误，请重试...')
   continue
  break

 if choice == 'Y' or choice == 'y':
  while True:
   print('\n请选择（输入 q 退出）：\n')
   print('1. 上架新品\n\n2. 下架商品\n\n3. 修改商品信息')
   choice = input('\n>')
   if not (choice == '1' or choice == '2' or choice == '3' or choice == 'q'):
    print('输入有误，请重试...')
    continue

   # 上架新品
   if choice == '1':
    while True:
     if_add = False # 是否添加商品的标志，初始为False
     new_commodity = input('\n输入商品名：')

     product_file = open('product_list.txt', 'r')

     for product_line in product_file:
      commodity = product_line.strip('\n').split(', ')[0]  # 获取商品列表中的商品名
      if new_commodity == commodity:
       print('\n此商品已在货架上...')
       continue
      else:
       while True:
        if_sure = input('\n确定上架新品 %s 吗？（Y/N）：' % new_commodity)
        if not (if_sure == 'Y' or if_sure == 'y' or if_sure == 'N' or if_sure == 'n'):
         print('\n输入有误，请重试...')
         continue
        break
       # 确定上架新品
       if if_sure == 'Y' or if_sure == 'y':
        while True:  # 输入单价
         price = input('\n请输入单价：')
         if not price.isdigit():
          print('\n输入有误，请重试...')
          continue
         break
        while True:  # 输入库存
         stock = input('\n请输入库存：')
         if not stock.isdigit():
          print('\n输入有误，请重试...')
          continue
         break
        new_line = '\n' + new_commodity + ', ' + price + ', ' + stock
        open('product_list.txt', 'a').writelines(new_line)
        print('\n成功上架新品 %s ,单价 %s 元，库存 %s 件' % (new_commodity, price, stock))

        while True:
         option = input('\n是否继续添加？(Y/N):')
         if not (option == 'Y' or option or option == 'N' or option == 'n'):
          print('\n输入有误，请重试...')
          continue
         break
        if option == 'Y' or option == 'y':
         if_add = True
         break # 跳出for循环
        else:
         break
       # 取消上架新品
       else:
        if_add = False
        break # 跳出for循环
     product_file.close()

     if if_add is True:
      continue
     else:
      break # 跳出while循环

   # 下架商品
   elif choice == '2':
    while True:
     del_num = input('\n请输入您想下架商品的序号：')
     if not (del_num.isdigit() or int(del_num) > 0 and int(del_num) <= len(commodity_list)):
      print('\n输入有误，请重试...')
      continue
     break

    del_num = int(del_num)
    del_commodity = commodity_list[del_num - 1][0]

    with open('product_list.txt', 'r') as old_file:
     with open('product_list.txt', 'r+') as new_file:

      current_line = 0

      # 定位到需要删除的行
      while current_line < (del_num - 1):
       old_file.readline()
       current_line += 1

      # 当前光标在被删除行的行首，记录该位置
      seek_point = old_file.tell()

      # 设置光标位置
      new_file.seek(seek_point, 0)

      # 读需要删除的行，光标移到下一行行首
      old_file.readline()
      
      # 被删除行的下一行读给 next_line
      next_line = old_file.readline()

      # 连续覆盖剩余行，后面所有行上移一行
      while next_line:
       new_file.write(next_line)
       next_line = old_file.readline()

      # 写完最后一行后截断文件，因为删除操作，文件整体少了一行，原文件最后一行需要去掉
      new_file.truncate()

    print('\n您已成功下架 %s ！' % del_commodity)

   # 修改商品信息
   elif choice == '3':

    # 修改商品信息
    def mod_commodity_info(i, j):
     i = int(i)
     j = int(j)
     with open('product_list.txt', 'r+') as f:
      current_line = 0
      while current_line < i - 1:
       f.readline()
       current_line += 1
      seek_point = f.tell()
      f.seek(seek_point, 0)

      # 修改商品名
      if j == 1:
       update_line = mod_name() + ', ' + commodity_list[i-1][1] + ', ' + commodity_list[i-1][2] + '\n'
      # 修改商品价格
      elif j == 2:
       update_line = commodity_list[i-1][0] + ', ' + mod_price() + ', ' + commodity_list[i-1][2] + '\n'
      # 修改商品库存
      else:
       update_line = commodity_list[i-1][0] + ', ' + commodity_list[i-1][1] + ', ' + mod_stock() + '\n'
      
      f.write(update_line)
     return
    
    def mod_name():
     new_name = input("\n请输入新的商品名：")
     return new_name

    def mod_price():
     new_price = input("\n请输入新的商品单价：")
     return new_price

    def mod_stock():
     new_stock = input("\n请输入新的商品库存：")
     return new_stock

    # 修改商品单价
    def mod_commodity_price(i):
     i = int(i)
     with open('product_list.txt', 'r+') as f:
      current_line = 0
      while current_line < i -1:
       f.readline()
       current_line += 1
      seek_point = f.tell()
      f.seek(seek_point, 0)
      new_price = input()


    while True:
     i = input("\n请输入需要编辑的商品序号（输入 c 取消）：")
     if not (i.isdigit or i == 'c' or int(i) > 0 and int(i) <= len(commodity_list)):
      print("\n输入有误，请重试...")
      continue
     elif i == 'c':
      break
     else:
      while True:
       j = input("\n请选择需要编辑的选项（输入 c 取消）：\n\n1. 商品名\n\n2. 单价\n\n3. 库存\n\n>")
       if not (j == 'c' or j == '1' or j == '2' or j == '3'):
        print("\n输入有误，请重试...")
        continue
       break
      if j == 'c':
       break
      else:
       mod_commodity_info(i, j)

   else:
    exit('\n您已退出商城...')
 else:
  exit('\n您已退出商城...')