62进制与10进制转换，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
# python_version: 3.7.1

import string
import unittest


class Base62(object):
    """
    基于abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789共计62个ascii字符
    构建62进制编码, 实现正整型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) * (self.BASE ** 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
        """
        if not isinstance(digit, int) or digit < 0:
            raise TypeError('请输入正整数')
        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
        """
        check = sum([1 for ele in str62 if ele not in self.BASE_STR])
        if check > 0 or len(str62) == 0 or not isinstance(str62, str):
            raise TypeError('请输入正确的62进制数')
        return self.__62to10(str62)        


class TestBase62(unittest.TestCase):

    def setUp(self):
        self.code = Base62()

    def test_encode_10to62_border(self):
        self.assertEqual(first=self.code.encode_10to62(0), second='a')
        self.assertEqual(first=self.code.encode_10to62(1), second='b')
        self.assertEqual(first=self.code.encode_10to62(61), second='9')
        self.assertEqual(first=self.code.encode_10to62(62), second='ba')

    def test_encode_10to62_nornal(self):
        self.assertEqual(first=self.code.encode_10to62(122262), second='FX8')
    
    def test_decode_62to10_border(self):
        self.assertEqual(first=self.code.decode_62to10('a'), second=0)
        self.assertEqual(first=self.code.decode_62to10('b'), second=1)
        self.assertEqual(first=self.code.decode_62to10('9'), second=61)
        self.assertEqual(first=self.code.decode_62to10('ba'), second=62)

    def test_decode_62to10_nornal(self):
        self.assertEqual(first=self.code.decode_62to10('FX8'), second=122262)

    def test_encode_10to62_datatype_error(self):
        self.assertRaises(TypeError, self.code.encode_10to62, -1)
        self.assertRaises(TypeError, self.code.encode_10to62, -1212)
        self.assertRaises(TypeError, self.code.encode_10to62, 22.1212)
        self.assertRaises(TypeError, self.code.encode_10to62, '')
        self.assertRaises(TypeError, self.code.encode_10to62, 'safs#121')

    def test_decode_62to10_datatype_error(self):
        self.assertRaises(TypeError, self.code.decode_62to10, -1)
        self.assertRaises(TypeError, self.code.decode_62to10, -1212)
        self.assertRaises(TypeError, self.code.decode_62to10, 22.1212)
        self.assertRaises(TypeError, self.code.decode_62to10, '')
        self.assertRaises(TypeError, self.code.decode_62to10, 'safs#121')


if __name__ == "__main__":
    unittest.main()

a="aa"
b=Base32()
a==b.encode_10to62(b.decode_62to10(a))