from random import Random
def random_str(randomlength=8): //固定长度8
str = '' //str初始为空
chars = 'AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz0123456789'
length = len(chars) - 1
random = Random() //random模块用于生成随机数
for i in range(randomlength): //循环生成随机字符串
str+=chars[random.randint(0, length)]
return str