62进制与10进制转化，主要用于短URL生成解析

base62.py

#!/usr/bin/env python
# encoding: utf-8
# author: toddlerya
# date: 2019/03/31

import string


class Base62(object):
    """
    基于abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789共计62个ascii字符
    构建62进制编码, 实现正整形十进制数据字符编码和解码
    """
    def __init__(self):
        self.BASE_STR = string.ascii_letters + string.digits
        self.BASE = len(self.BASE_STR)

    def __10to62(self, digit, value=None):
        # 小心value参数的默认传参数陷阱
        # 不应写为value=[], 这将导致只有一次初始化, 每次调用列表的值都会累加
        # 应该声明为None, 只有为None才进行初始化, 这样能保持每次调用都会初始化此参数
        # https://pythonguidecn.readthedocs.io/zh/latest/writing/gotchas.html
        if value is None:
            value = list()
        rem = int(digit % self.BASE)
        value.append(self.BASE_STR[rem])
        div = int(digit / self.BASE)
        if div > 0:
            value = self.__10to62(div, value)
        return value

    def __62to10(self, str_value):
        value_list = list(str_value)
        value_list.reverse()
        temp_list = [self.BASE_STR.index(ele) * (62 ** n) for n, ele in enumerate(value_list)]
        return sum(temp_list)

    def encode_10to62(self, digit: int) -> str:
        """
        10进制转为62进制
        """
        value = self.__10to62(digit)
        value.reverse()
        value = ''.join(value)
        return value

    def decode_62to10(self, str62: str) -> int:
        """
        62进制转为10进制
        """
        return self.__62to10(str62)        



def main():
    code = Base62()
    print(code.encode_10to62(0))
    print(code.encode_10to62(10))
    print(code.encode_10to62(61))
    print(code.encode_10to62(62))
    print(code.encode_10to62(122262))
    print('==' * 20)
    print(code.decode_62to10('a'))
    print(code.decode_62to10('k'))
    print(code.decode_62to10('9'))
    print(code.decode_62to10('ab'))
    print(code.decode_62to10('ba'))
    print(code.decode_62to10('FX8'))

if __name__ == "__main__":
    main()