Python 3 简易用户登录系统，输错三次密码锁定账…

import getpass　　　　# 使用getpass模块，输入密码的时候是密文
import json
username = input("input username:")
with open("users.txt",'r') as f:　　# 用户表，保存用户名和密码
   contents = f.read()
users = json.loads(contents)   # convert to dict type
with open("lock.txt",'r') as lock_file:　　　　# lock.txt保存被锁定用户，这里读取出来用于判断用户输入的账号是否已经被锁定
    lock_users = lock_file.readlines()
lock_user_list=list()
for lock_user in lock_users:
    lock_user_list.append(lock_user.strip())    # 转换成列表，并去除每个元素后面的换行符
if username in lock_user_list:
    print("your account {username} has been locked, please contact the administrator.".format(username=username))    # 字符串格式化，在lock.txt直接退出
    exit()
count = 0　　　　　　# 计数器，用于统计用户输入密码次数
count_left = 3　　　　# 还剩几次
if username in users:　　　　# 外层循环，判断用户是否存在，不存在直接退出，存在则进入密码输入环节
    while count < 3:　　　　　# 计数3次
       #password = input("input your password:")
       password = getpass.getpass("input your password:")    # getpass模块
       if password == users[username]:
           print("welcome aboard, {username}!".format(username = username))
       else:
           count_left -= 1
           while count_left:
               print("invalid password, try again and {count_left} times left!".format(count_left=count_left))
               break
           count += 1
    else:
        print("invalid password, try maximum times, your account has been locked.")    # 尝试超过最大次数限制，锁定账户，将username存进lock.txt，一行一个
        block = open("lock.txt","a")
        block.write(username+'\r')
        block.close()
else:
    print("no such username: {username}, exit.".format(username=username))
    exit()