beautifulsoup4库安装、使用

(venv) D:pytest>pip install beautifulsoup
Collecting beautifulsoup
  Using cached https://files.pythonhosted.org/packages/1e/ee/295988deca1a5a7accd783d0dfe14524867e31abb05b6c0eeceee49c759d/BeautifulSoup-3.2.1.tar.gz
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "C:Users1AppDataLocalTemppip-install-mav7d0boeautifulsoupsetup.py", line 22
        print "Unit tests have failed!"
                                      ^
    SyntaxError: Missing parentheses in call to 'print'. Did you mean print("Unit tests have failed!")?

    ----------------------------------------
Command "python setup.py egg_info" failed with error code 1 in C:Users1AppDataLocalTemppip-install-mav7d0boeautifulsoup

哦，大概是beautifulsoup已经被炸了，需要pip install beautifulsoup4 或者直接bs4

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BeautifulSoup类的基本元素

基本元素	说明
Tag	标签，最基本的信息组织单元，分别用<>  和</>标明开头和结尾
Name	标签的名字，<p>…</p>的名字是'p'，格式：<tag>.name
Attributes	标签的属性，字典形式组织，格式：<tag>.attrs
NavigableString	标签内非属性字符串，<>…</>中字符串，格式：<tag>.string
Comment	标签内字符串的注释部分，一种特殊的Comment类型

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标签树的下行遍历

属性	说明
.contents	子节点的列表，将<tag>所有儿子节点存入列表
.children	子节点的迭代类型，与.contents类似，用于循环遍历儿子节点
.descendants	子孙节点的迭代类型，包含所有子孙节点，用于循环遍历