TypeError: POST data should be bytes, an iterable of bytes, or a file object. It cannot be of type s

import urllib.request
import urllib.parse
def request():
#定义 HTTP的头部
headers = {'User-Agent':'Mozilla/5.0','x-my-header':'my value'}
req = urllib.request.Request('http://blog.kamidox.com',headers = headers)
s = urllib.request.urlopen(req)
print(s.read(100))
print(req.headers)
s.close()
def request_post_debug():
#post
data = {'username':'kamidox','password':'xxxxxxx'}
headers = {'User-Agent':'Mozilla/5.0'}
req = urllib.request.Request('http://www.douban.com',data  = urllib.parse.urlencode(data),headers = headers)
#创建一个打开器
opener = urllib.request.build_opener(urllib.request.HTTPHandler(debuglevel = 1))
s = opener.open(req)
print(s.read(100))
s.close()

if __name__=='__main__':
request_post_debug()

Request('http://www.douban.com',data  = urllib.parse.urlencode(data).encode(encoding='UTF8'),headers = headers)