吴裕雄--python学习笔记：爬虫包的更换

python 3.x报错：No module named 'cookielib'或No module named 'urllib2'

1.    ModuleNotFoundError: No module named 'cookielib'
Python3中，import  cookielib改成 import  http.cookiejar,然后方法里cookielib也改成 http.cookiejar。

2.    ModuleNotFoundError: No module named 'urllib2'

Python 3中urllib2用urllib.request替代。

在Python官方文档里面已有说明：

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)

3.    NameError: name 'raw_input' is not defined

Python 3中用input()替换raw_input()

4.    UserWarning: You provided Unicode markup but also provided a value for from_encoding. Your from_encoding will be ignored.

注意这句：warnings.warn("You provided Unicode markup but also provided a value for from_encoding. Your from_encoding will be ignored.") 原因：python3 缺省的编码是unicode, 再在from_encoding设置为utf8, 会被忽视。

Python 3中soup = BeautifulSoup(html_doc, "html.parser", from_encoding="utf-8")这一句中删除from_encoding="utf-8"