HTTPHandler在py2和py3中的区别.

在Python2中，使用urlib2的接口，可以把收发包的内容直接打印在屏幕上，示例

import urllib2 
 
httpHandler = urllib2.HTTPHandler(debuglevel=1)  
httpsHandler = urllib2.HTTPSHandler(debuglevel=1)  
opener = urllib2.build_opener(httpHandler, httpsHandler)  
urllib2.install_opener(opener)  
res = urllib2.urlopen('http://www.baidu.com')

Python3合并了urllib和urllib2的库
Python3版本

import urllib.request

http_handler = urllib.request.HTTPHandler()
https_handler = urllib.request.HTTPSHandler(debuglevel=1)
opener = urllib.request.build_opener(http_handler, https_handler)
urllib.request.install_opener(opener)
urllib.request.urlopen("http://www.baidu.com")

如果你只是想得到header信息的话
imoprt xxx
res = urllib.request.urlopen("http://www.baidu.com")

print(res.info())