Python爬虫入门遇到的坑

1. 环境

- Python
　　mac os预装的python

$ python -V  
Python 2.7.10
$ where python
/usr/bin/python
$ ls /System/Library/Frameworks/Python.framework/Versions
2.3     2.5     2.6     2.7     Current
$ ls /Library/Frameworks/Python.framework/Versions （用户安装的目录）

- IDE
　　Pycharm
- 辅助
　　安装pip

sudo easy_install pip

- Python库

sudo pip install requests （默认安装requests 2.13.0） 
sudo pip install BeautifulSoup （默认安装BeautifulSoup 3.2.1）
sudo pip install lxml （默认安装lxml 3.7.3)

2. 问题

- 问题1

- 问题2

代码：
soup = BeautifulSoup(html, 'lxml')
报错：
Traceback (most recent call last):
File "/Users/cuizhenyu/Documents/Codes/Python/DownloadMeitu/LibBeautifulSoupTest.py", line 15, in <module>
soup = BeautifulSoup(html, 'lxml') #soup = BeautifulSoup(html, 'lxml')报错
File "/Library/Python/2.7/site-packages/BeautifulSoup.py", line 1522, in __init__
BeautifulStoneSoup.__init__(self, *args, **kwargs)
File "/Library/Python/2.7/site-packages/BeautifulSoup.py", line 1147, in __init__
self._feed(isHTML=isHTML)
File "/Library/Python/2.7/site-packages/BeautifulSoup.py", line 1189, in _feed
SGMLParser.feed(self, markup)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/sgmllib.py", line 104, in feed
self.goahead(0)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/sgmllib.py", line 138, in goahead
k = self.parse_starttag(i)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/sgmllib.py", line 296, in parse_starttag
self.finish_starttag(tag, attrs)
File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/sgmllib.py", line 338, in finish_starttag
self.unknown_starttag(tag, attrs)
File "/Library/Python/2.7/site-packages/BeautifulSoup.py", line 1338, in unknown_starttag
self.endData()
File "/Library/Python/2.7/site-packages/BeautifulSoup.py", line 1251, in endData
(not self.parseOnlyThese.text or
AttributeError: 'str' object has no attribute 'text'
解决：
当前BeautifulSoup是v3版，不支持lxml等，需用v4版。