Python is a credit card system that implements functions such as online shopping malls, transfers, deposits and withdrawals, etc.

1. Requirements

2. Ideas

1. Shopping buy

Receive credit card credit card available balance,

Return the consumption amount

2. Credit card (ATM) category

Receive credit card available balance, total arrears, remaining arrears, and deposits since the last operation

Among them: 1. Each transaction type does not process money separately, nor does it record separate running accounts. Each transaction type calls the function that processes money (incoming transaction type, transaction amount)

　　2. The function that handles money calls the configuration file for the addition, subtraction, and interest rate of each transaction type

Return to the credit card’s available balance, total arrears, remaining arrears, and deposits after this operation

3.Client

Bank administrator registration and login

Ordinary user registration and login

Sending requirements: registration, login, transaction type, transaction amount

4. Server side

Call the shopping class and create the shopping object (shopping interface)

Call the credit card (ATM) class to process repayments, transfers and other operations, record interest on a monthly basis, and write to files

5. Scheduled tasks

Execute the program regularly to calculate interest.

3. Code

3.1 Configuration File

import os
 
BASE_DIR = os.path.dirname(os.path.dirname(__file__)) #配置文件的上层目录
DB_DIR=os.path.join(BASE_DIR,'db')  #数据文件夹
ADMIN=os.path.join(DB_DIR,'admin')
ALL_USERS=os.path.join(DB_DIR,'allusrs')
A=os.path.join(BASE_DIR,'db','s')
LOG=os.path.join(BASE_DIR,'log')
 
 
TRANSACTION={
 'repay':{'action':'plus','interest':0}, #还款
 'withdraw':{'action':'minus','interest':0.05},#取现
 'transfer':{'action':'minus','interest':0.05},#转账
 'consume':{'action':'minus','interest':0},#消费
 'saving':{'action':'plus','interest':0} #存款
}
 

3.2 Public Class

3.2.1 Shopping category

class buy:
 goods=[
   {"name": "电脑", "price": 1999},
   {"name": "鼠标", "price": 10},
   {"name": "游艇", "price": 20},
   {"name": "美女", "price": 998},
  ]
 
 def __init__(self,money,consumption,shopping_cart,):
  self.money=money
  self.consumption=consumption
  self.shopping_cart=shopping_cart
 
 def gouwu(self): #购物模块
  print('您的当前余额为：%d' %self.money)
  num=int(input('请输入商品序号：'))
  num-=1
  if self.goods[num]["name"] in self.shopping_cart.keys():    #goods[num]["name"]取商品名
   self.shopping_cart[self.goods[num]["name"]]['n']+=1     #商品数量+1
  else:
   self.shopping_cart[self.goods[num]["name"]]={"price":self.goods[num]["price"],'n':1,} # 创建购物车字典 {keys{"price"：价格,数量：1}}
  self.money-=self.shopping_cart[self.goods[num]["name"]]["price"]*self.shopping_cart[self.goods[num]["name"]]['n']  #单价*数量
  self.consumption+=self.shopping_cart[self.goods[num]["name"]]["price"]*self.shopping_cart[self.goods[num]["name"]]['n']
 
 def yichu(self): #移除购物车模块
  c=int(input(' 请输入0/1选择是否移除购物车商品, 移除请输入1:'))
  if c==1:
   e=int(input(' 请输入要移除的商品序号:'))
   d=self.goods[e-1]
   if d in self.shopping_cart.keys():    #判断要移除的商品是否在购物车内
    self.shopping_cart.remove(d)   #移除商品
    self.money=self.money+self.goods[self.goods.index(d)]["price"]    #余额增加
    self.consumption=self.consumption-self.goods[self.goods.index(d)]["price"] #消费总额减少
   else:
    print('商品不存在')
 def chongzhi(self): #充值模块
  pay=int(input('请输入充值金额'))
  self.money=self.money+pay
  print('您的当前余额为：%d' % self.money) #显示当前余额
 
 def main(self):
  print('商品清单：')
  for m,n in enumerate(self.goods,1):
   print(m)
   for v in n.values():
    print(v)
   print('=============')
  #消费总额清零
  self.consumption=0
  buy=True #定义默认一直购物
  while buy:
   price=0 #定义初始价格
   b=1 #定义默认不退出购物或充值状态
   if self.money>=price:
 
  #消费模块；金钱大于货物价格时，才能开始购物
    while self.money>=price:
  #计价模块，有钱就可以一直购物
     self.gouwu()
  #移除购物车商品模块
     self.yichu()
     if self.money>=0:
      print('您的当前余额为：%d' %self.money)   #显示当前余额
      b=int(input(' 请输入0/1选择是否继续购物, 购物请输入1:'))
      if b==0:  #
       break #退出计价模块
    if b==0:   #如果不购物
     break   #不购物退出整个购物程序
  #充值模块
   else:
    while self.money<price:   #金钱不足，可多次充钱，直到能买得起货物
     a=int(input(' 您的余额不足，请输入0/1选择是否充值，充值请输入1:'))
     if a==1:
      self.chongzhi()
     else:
      break   #退出充值模块
     if a==0:
      break   #不充值退出程序
  #打印购物车商品名、商品价格、消费总额、余额
  print('您的消费清单为：')
  for m,n in self.shopping_cart.items():
   print(m,n['price'],n['n'])
     #打印消费清单
   print('=============')
  print('您的当前余额为：%d,您的消费总额为：%d' % (self.money,self.consumption) )   #打印消费总额
  return self.consumption

3.2.2 Credit Card ATM

class Atm:
 credit=15000 #信用卡额度
 def __init__(self,balance,debt,remaining_debt,interest,saving,id):
  self.id=id    #信用卡id
  self.balance=balance  #信用卡可用金额
  self.debt=debt   #总欠款
  self.remaining_debt=remaining_debt #剩余欠款
  self.interest=interest  #手续费
  self.saving=saving  #存款
  self.now_time=time.strftime("%Y-%m-%d %H:%M:%S")
  self.now_data=time.strftime("%Y-%m")
  self.struct_time=time.gmtime(time.time())
  if self.struct_time.tm_mday>22:
   self.now_data=self.struct_time.tm_year+'-'+str(int(self.struct_time.tm_mon)+1)
 
 def account_info(self):#打印账户信息
  return '账户id%s 信用卡额度%s;信用卡可用金额%s;剩余欠款%s;'%(self.id,self.credit,self.balance,self.remaining_debt,)
 def ret_account_info(self):
  return [self.id,self.credit,self.balance,self.debt,self.remaining_debt,self.interest]
 def repay(self,amount):#还款
  self.handel_money('repay',amount)
 def withdraw(self,amount): #取现
  self.handel_money('withdraw',amount)
 def transfer(self,amount): #转账
  self.handel_money('transfer',amount)
 def consume(self,amount): #消费
  self.handel_money('consume',amount)
 def saves(self,amount):
  self.handel_money('saving',amount)
 def transaction(self,a,amount):
  dic={
   '1':self.repay,
   '2':self.withdraw,
   '3':self.transfer,
   '4':self.consume,
   '5':self.saves
  }
  print("debug: a:",type(a),"amount:",type(amount))
 
  print(a)
  print(dic[a])
  print(dic["5"])
  dic[a](amount)
  print("end debug")
 
 def handel_money(self,transaction,amount): #交易类型，
  amount=int(amount)
  interest=amount*settings.TRANSACTION[transaction]['interest'] #手续费计算
  if settings.TRANSACTION[transaction]['action']=='plus':
 
   if amount<=self.remaining_debt:
    self.remaining_debt-=amount
    self.balance+=amount
   else:
    self.balance+=self.remaining_debt
    self.remaining_debt=0
    self.saving+=amount-self.remaining_debt
  else:
 
   if self.saving<amount:
    self.saving=0
    a=amount-self.saving
    self.balance-=a+interest-self.saving
    # self.debt+=amount+interest
    self.remaining_debt+=a+interest
  a='time:%s id:%s transaction: %s amount:%s interest %s \n'%(self.now_time,self.id,transaction,amount,interest)
  print(a)
  mulu=os.path.join(settings.ALL_USERS,self.id)
  path_name_liushui=os.path.join(mulu,str(self.id)+'name_liushui',str(self.now_data))
 
  with open(path_name_liushui,'a')as f:   #记录流水信息
   f.write(a)
 
  s=[self.balance,self.debt,self.remaining_debt,self.interest,self.saving,]  #更新基本信息
  path_name_base=os.path.join(mulu,str(self.id)+'name_base')
  pickle.dump(s,open(path_name_base,'wb'))

　3.3 Server side:

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
import sys,os
import hashlib
import pickle
import time
import socketserver
sys.path.append(os.path.dirname(os.path.dirname(__file__)))
from config import settings
from lib import modules
from lib.modules import *
 
class Myserver(socketserver.BaseRequestHandler):
 
 def md5(self,pwd):
  '''
  对密码进行加密
  :param pwd: 密码
  :return:
  '''
  hash=hashlib.md5(bytes('xx7',encoding='utf-8'))
  hash.update(bytes(pwd,encoding='utf-8'))
  return hash.hexdigest()
 
 
 def login(self,usrname,pwd,x):
  '''
  登陆
  :param usrname: 用户名
  :param pwd: 密码
  :return:是否登陆成功
  '''
  conn=self.request
  if x=='1':
   path_name_pwd=os.path.join(settings.ADMIN,usrname)
  else:
   mulu=os.path.join(settings.ALL_USERS,usrname)
   path_name_pwd=os.path.join(mulu,usrname+'name_pwd')
  s=pickle.load(open(path_name_pwd,'rb'))
  if usrname in s:
    if s[usrname]==self.md5(pwd):  #和加密后的密码进行比较
    return True
    else:
    return False
  else:
   return False
 
 
 def regist(self,usrname,pwd,x):
  '''
  注册
  :param usrname: 用户名
  :param pwd: 密码
  :return:是否注册成功
  '''
 
  conn=self.request
  if x=='1':
   mulu=os.path.join(settings.ADMIN,usrname)
  else:
   mulu=os.path.join(settings.ALL_USERS,usrname)
 
 
  if os.path.exists(mulu):
    return False
  else:
   os.mkdir(mulu)
   s={}
   s[usrname]=self.md5(pwd)
   path_name_pwd=os.path.join(mulu,usrname+'name_pwd')
   pickle.dump(s,open(path_name_pwd,'wb'))
   path_name_base=os.path.join(mulu,usrname+'name_base')
   pickle.dump([15000,{},0,0,0],open(path_name_base,'wb'))
   path_name_liushui=os.path.join(mulu,usrname+'name_liushui')
   os.mkdir(path_name_liushui)
   return True
 
 def user_identity_authentication(self,usrname,pwd,ret,x):
  '''
  判断注册和登陆，并展示用户的详细目录信息，支持cd和ls命令
  :return:
  '''
  conn=self.request
  if ret=='1':
   r=self.login(usrname,pwd,x)
   if r:
    conn.sendall(bytes('y',encoding='utf-8'))
   else:
    conn.sendall(bytes('n',encoding='utf-8'))
  elif ret=='2':
   # print(usrname,pwd)
   if x=='1':
    r=self.regist(usrname,pwd,x)
   else: #用户注册
    s=[0,1]
    pickle.dump(s,open(settings.A,'wb'))
    while True:
     ret=pickle.load(open(settings.A,'rb'))
     if ret[0]==0:
      time.sleep(30)
      continue
     elif ret[0]==1 or ret[0]==2:
      break #默认值已更改，银行管理员已操作
 
    if ret[0]==1: #如果管理员同意
     r=self.regist(usrname,pwd,x)
    else:
     r=0
    s=[0,0]
    pickle.dump(s,open(settings.A,'wb'))
   if r:
    conn.sendall(bytes('y',encoding='utf-8'))
   else:
    conn.sendall(bytes('n',encoding='utf-8'))
 def interactive(self,usrname): #进行交互
  conn=self.request
  while True:
   c=conn.recv(1024) #接收用户交互选项
   r=str(c,encoding='utf-8')
   mulu=os.path.join(settings.ALL_USERS,usrname)
   path_name_base=os.path.join(mulu,usrname+'name_base')
   s=pickle.load(open(path_name_base,'rb'))
 
   #打印账户信息
   obj=modules.Atm(s[0],s[1],s[2],s[3],s[4],usrname) #Atm对象
   a=obj.account_info() #接收账户信息
   conn.sendall(bytes(a,encoding='utf-8'))
 
   b=obj.ret_account_info()
 
 
 
   if r== '4':
    buy_obj=modules.buy(b[2],0,{})
    amount=buy_obj.main()
   elif r=='q':
    break
   else:
    s=conn.recv(1024)
    amount=str(s,encoding='utf-8')
 
   obj.transaction(r,amount)
 
 
  pass
 
 
 def handle(self):
  conn=self.request
  x=conn.recv(1024)
  x=str(x,encoding='utf-8')
  conn.sendall(bytes('收到用户类别',encoding='utf-8'))
  while True:
   if x=='1' or x=='2':
    b=conn.recv(1024)
    ret=str(b,encoding='utf-8')
    conn.sendall(bytes('b ok',encoding='utf-8'))
    c=conn.recv(1024)
    r=str(c,encoding='utf-8')
    usrname,pwd=r.split(',')
    print(usrname,pwd)
    self.user_identity_authentication(usrname,pwd,ret,x) #登陆或注册验证
    if x=='2':#普通用户身份验证成功后
     self.interactive(usrname)
 
     pass
 
    break
   elif x=='q':
    break
 
if __name__=='__main__':
 sever=socketserver.ThreadingTCPServer(('127.0.0.1',9999),Myserver)
 sever.serve_forever()

3.4 Client

#!/usr/bin/env python
# -*- coding: utf-8 -*-
'''
本程序作为用户或银行管理员的入口，其中c=1代表银行管理员，c=2代表普通用户
'''
import pickle
import sys
import time
import os
import socket
sys.path.append(os.path.dirname(os.path.dirname(__file__)))
from config import settings
from lib import *
from lib.modules import *
 
def login(usrname,pwd):
 '''
 登陆
 :param usrname:用户名
 :param pwd:密码
 :return:是否登陆成功
 '''
 obj.sendall(bytes(usrname+','+pwd,encoding='utf-8'))
 ret=obj.recv(1024)
 r=str(ret,encoding='utf-8')
 if r=='y':
  return 1
 else:
  return 0
 
def regist(usrname,pwd,x):
 '''
 注册
 :param usrname:用户名
 :param pwd:密码
 :return:是否注册成功
 '''
 obj.sendall(bytes(usrname+','+pwd,encoding='utf-8'))
 
 ret=obj.recv(1024)
 r=str(ret,encoding='utf-8')
 if r=='y':
  return 1
 else:
  return 0
def user_identity_authentication(usrname,pwd,x):
 '''
 选择登陆或注册，展示用户的详细目录信息，支持cd和ls命令
 :return:
 '''
 a=input('请选择1.登陆 2.注册')
 obj.sendall(bytes(a,encoding='utf-8'))
 obj.recv(1024)
 if a=='1':
  ret=login(usrname,pwd)
  if ret:
   print('登陆成功')
   return 1
  else:
   print('用户名或密码错误')
   return 0
 elif a=='2':
  ret=regist(usrname,pwd,x)
  if ret:
   print('注册成功')
   return 1
  else:
   print('用户名已存在或银行管理员拒绝')
   return 0
def main(x):
 usrname=input('请输入用户名')
 pwd=input('请输入密码')
 if user_identity_authentication(usrname,pwd,x): #如果验证身份成功
  if x=='1': #处理用户注册信息
 
   while True:
    s=pickle.load(open(settings.A,'rb'))
    if s[1]==0:
     time.sleep(30)
     continue
    elif s[1]==1:
     while True:
      a=input('用户请求注册，输入1同意，2拒绝')
      if a=='1':
       s=[1,0]
       pickle.dump(s,open(settings.A,'wb'))
       break
      elif a=='2':
       s=[2,0]
       pickle.dump(s,open(settings.A,'wb'))
       break
      else:
       print('输入有误')
     break
  else: #普通用户登陆后
   interactive() #进行交互
 
 
def interactive():
 while True:
  a=input('请选择 1.还款 2.取现 3.转账 4.消费 5.存钱 q退出')
  obj.sendall(bytes(a,encoding='utf-8'))
  r=obj.recv(1024) #接收账户信息
  ret=str(r,encoding='utf-8')
  print(ret)
  if a !='4'and a !='q':
   b=input('请输入金额')
   obj.sendall(bytes(b,encoding='utf-8'))
  elif a=='q':
   break
 
 
 
obj=socket.socket() #创建客户端socket对象
obj.connect(('127.0.0.1',9999))
while True:
 x=input('请选择1.银行管理员 2.用户 q、退出')
 obj.sendall(bytes(x,encoding='utf-8'))
 obj.recv(1024) #确认收到用户类别
 if x=='1' or x=='2':
  main(x)
  break
 elif x=='q':
  break
 else:
  print('输入有误请重新输入')
 
obj.close()

　3.5 Timed tasks

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import os,sys
import json,pickle
import time
sys.path.append(os.path.dirname(os.path.dirname(__file__)))
from config import settings
 
 
 
def main():
 card_list = os.listdir(settings.ALL_USERS)
 for card in card_list:
  basic_info = pickle.load(open(os.path.join(settings.ALL_USERS, card, card+'name_base')))
  struct_time = time.localtime()
 
  # 循环账单列表，为每月的欠款计息。并写入到当月账单中
  for item in basic_info['debt']:
   interest = item['total_debt'] * 0.0005
   if basic_info[4] >= interest:
    basic_info[4] -= interest
   else:
    temp = interest - basic_info[4]
    basic_info[4]=0
    basic_info[0] -= temp
    pickle.dump(
      basic_info,
      open(os.path.join(settings.ALL_USERS, card, card+'name_base'),'w')
    )
 
  # 如果当前等于10号(9号之前)
  # 当前余额为负值，则将值添加到账单列表中，开始计息，同时，本月可用额度恢复。
  date = time.strftime("%Y-%m-%d")
  if struct_time.tm_mday == 11 and basic_info[2]>0:
   dic = {'date': date,
     "total_debt": basic_info[2],
     "balance_debt": basic_info[2],
     }
   basic_info[1].append(dic)
   # 恢复可用额度
   basic_info[0] = 15000
  pickle.dump(
   basic_info,
   open(os.path.join(settings.ALL_USERS, card, card+'name_base'),'w')
    )
 
 
def run():
 main()
　　

The above is about using python to develop an online shopping mall credit card system. Students in need can refer to it.