python过滤非法字符

# 过滤非法字符
def sql_filter(sql, max_length=20):
    dirty_stuff = ["\"", "\\", "/", "|", "&", "*", "'", "=", "-", "#", ";", "<", ">", "+", "%", "$", "(", ")", "%", "@","!"]
    for stuff in dirty_stuff:
        sql = sql.replace(stuff, "")
    return sql[:max_length]

username = "1234567890!@#!@#!@#$%======$%|&***"

username = sql_filter(username)  # SQL注入
print(username)

# 输出结果是:1234567890

import re

# username = "1234567890!@#!@#!@#$%======$%|&***"
username = "1234567890*"

# 检测到非法字符进入if
if not re.search(u'^[_a-zA-Z0-9\u4e00-\u9fa5]+$', username):
    msg = u"用户名不可以包含非法字符(!,@,#,$,%...)"
    print(msg)

s="fdgdfd,..,/[]"
import re

def remove_special(s):
    new=""
    for i in s:
        if  re.search(u'^[\\\_.a-zA-Z0-9\u4e00-\u9fa5]+$', i):
            new+=i
    return new

remove_special(s)