查閱Python官方文件裡面已有說明：

Note The urllib2 module has been split across several modules in
Python 3.0 named urllib.request and urllib.error. The 2to3 tool will
automatically adapt imports when converting your sources to 3.0
from urllib.request
import urlopen
response = urlopen(“http://www.google.com

”)
html = response.read()
print(html)

從這裡可以看出，是由於python版本之間差異導致的，Python 3中urllib2用urllib.request替代
正確用法：

import urllib.request
resp=urllib.request.urlopen('http://www.baidu.com')
html=resp.read()
print(html)