在字符串值前面的“ u”符号是什么意思？

是的，简而言之，我想知道为什么我看到我的键和值前面有一个 u。

我正在呈现一个表单。该表单具有用于特定标签的复选框和用于 ip 地址的一个文本字段。我正在创建一个字典，键是在 list _ key 中硬编码的标签，字典的值取自表单输入(list _ value)。字典是创建的，但对于某些值，它的前面是 u。下面是字典的输出示例:

{u'1': {'broadcast': u'on', 'arp': '', 'webserver': '', 'ipaddr': u'', 'dns': ''}}

有人能解释一下我做错了什么吗。我没有得到误差时，我模拟类似的方法在符号。欢迎提出任何改进代码的建议。谢谢你

#!/usr/bin/env python


import webapp2
import itertools
import cgi


form ="""
<form method="post">
FIREWALL
<br><br>
<select name="profiles">
<option value="1">profile 1</option>
<option value="2">profile 2</option>
<option value="3">profile 3</option>
</select>
<br><br>
Check the box to implement the particular policy
<br><br>


<label> Allow Broadcast
<input type="checkbox" name="broadcast">
</label>
<br><br>


<label> Allow ARP
<input type="checkbox" name="arp">
</label><br><br>


<label> Allow Web traffic from external address to internal webserver
<input type="checkbox" name="webserver">
</label><br><br>


<label> Allow DNS
<input type="checkbox" name="dns">
</label><br><br>


<label> Block particular Internet Protocol  address
<input type="text" name="ipaddr">
</label><br><br>


<input type="submit">
</form>
"""
dictionarymain={}


class MainHandler(webapp2.RequestHandler):
def get(self):
self.response.out.write(form)


def post(self):
# get the parameters from the form
profile = self.request.get('profiles')


broadcast = self.request.get('broadcast')
arp = self.request.get('arp')
webserver = self.request.get('webserver')
dns =self.request.get('dns')
ipaddr = self.request.get('ipaddr')




# Create a dictionary for the above parameters
list_value =[ broadcast , arp , webserver , dns, ipaddr ]
list_key =['broadcast' , 'arp' , 'webserver' , 'dns' , 'ipaddr' ]


#self.response.headers['Content-Type'] ='text/plain'
#self.response.out.write(profile)


# map two list to a dictionary using itertools
adict = dict(zip(list_key,list_value))
self.response.headers['Content-Type'] ='text/plain'
self.response.out.write(adict)


if profile not in dictionarymain:
dictionarymain[profile]= {}
dictionarymain[profile]= adict


#self.response.headers['Content-Type'] ='text/plain'
#self.response.out.write(dictionarymain)


def escape_html(s):
return cgi.escape(s, quote =True)






app = webapp2.WSGIApplication([('/', MainHandler)],
debug=True)