from BeautifulSoup import BeautifulSoup           # HTML
from BeautifulSoup import BeautifulStoneSoup      # XML
import BeautifulSoup                              # ALL
                                                                                               
doc = [
    '<html><head><title>Page title</title></head>',
    '<body><p id="firstpara" align="center">This is paragraph <b>one</b>.',
    '<p id="secondpara" align="blah">This is paragraph <b>two</b>.',
    '</html>'
]
# BeautifulSoup 接受一个字符串参数
soup = BeautifulSoup(''.join(doc))

2. BeautifulSoup对象简介

用BeautifulSoup 解析 html文档时，BeautifulSoup将 html文档类似 dom文档树一样处理。BeautifulSoup文档树有三种基本对象。

2.1. soup BeautifulSoup.BeautifulSoup

type(soup)
<class 'BeautifulSoup.BeautifulSoup'>

2.2. 标记 BeautifulSoup.Tag

type(soup.html)
<class 'BeautifulSoup.Tag'>

2.3 文本 BeautifulSoup.NavigableString

type(soup.title.string)
<class 'BeautifulSoup.NavigableString'>

3. BeautifulSoup 剖析树

3.1 BeautifulSoup.Tag对象方法

获取标记对象（Tag）

标记名获取法，直接用 soup对象加标记名，返回 tag对象.这种方式，选取唯一标签的时候比较有用。或者根据树的结构去选取，一层层的选择

>>> html = soup.html
>>> html
<html><head><title>Page title</title></head><body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body></html>
>>> type(html)
<class 'BeautifulSoup.Tag'>
>>> title = soup.title
<title>Page title</title>

content方法

content方法根据文档树进行搜索，返回标记对象（tag）的列表

>>> soup.contents
[<html><head><title>Page title</title></head><body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body></html>]

>>> soup.contents[0].contents
[<head><title>Page title</title></head>, <body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body>]
>>> len(soup.contents[0].contents)
2
>>> type(soup.contents[0].contents[1])
<class 'BeautifulSoup.Tag'>

使用contents向后遍历树，使用parent向前遍历树

next 方法

获取树的子代元素，包括 Tag 对象和 NavigableString 对象。。。

>>> head.next
<title>Page title</title>
>>> head.next.next
u'Page title'

>>> p1 = soup.p
>>> p1
<p id="firstpara" align="center">This is paragraph<b>one</b>.</p>
>>> p1.next
u'This is paragraph'

nextSibling 下一个兄弟对象包括 Tag 对象和 NavigableString 对象

>>> head.nextSibling
<body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body>
>>> p1.next.nextSibling
<b>one</b>

与 nextSibling 相似的是 previousSibling，即上一个兄弟节点。

replacewith方法

将对象替换为，接受字符串参数

>>> head = soup.head
>>> head
<head><title>Page title</title></head>
>>> head.parent
<html><head><title>Page title</title></head><body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body></html>
>>> head.replaceWith('head was replace')
>>> head
<head><title>Page title</title></head>
>>> head.parent
>>> soup
<html>head was replace<body><p id="firstpara" align="center">This is paragraph<b>one</b>.</p><p id="secondpara" align="blah">This is paragraph<b>two</b>.</p></body></html>
>>>

搜索方法

搜索提供了两个方法，一个是 find，一个是findAll。这里的两个方法(findAll和 find)仅对Tag对象以及，顶层剖析对象有效，但 NavigableString不可用。

`findAll(`name, attrs, recursive, text, limit, **kwargs)

接受一个参数，标记名

寻找文档所有 P标记，返回一个列表

>>> soup.findAll('p')
[<p id="firstpara" align="center">This is paragraph<b>one</b>.</p>, <p id="secondpara" align="blah">This is paragraph<b>two</b>.</p>]
>>> type(soup.findAll('p'))
<type 'list'>

寻找 id="secondpara"的 p 标记，返回一个结果集

>>> pid = type(soup.findAll('p',id='firstpara'))
>>> pid
<class 'BeautifulSoup.ResultSet'>

传一个属性或多个属性对

>>> p2 = soup.findAll('p',{'align':'blah'})
>>> p2
[<p id="secondpara" align="blah">This is paragraph<b>two</b>.</p>]
>>> type(p2)
<class 'BeautifulSoup.ResultSet'>

利用正则表达式

>>> soup.findAll(id=re.compile("para$"))
[<p id="firstpara" align="center">This is paragraph<b>one</b>.</p>, <p id="secondpara" align="blah">This is paragraph<b>two</b>.</p>]

读取和修改属性

>>> p1 = soup.p
>>> p1
<p id="firstpara" align="center">This is paragraph<b>one</b>.</p>
>>> p1['id']
u'firstpara'
>>> p1['id'] = 'changeid'
>>> p1
<p id="changeid" align="center">This is paragraph<b>one</b>.</p>
>>> p1['class'] = 'new class'
>>> p1
<p id="changeid" align="center" class="new class">This is paragraph<b>one</b>.</p>
>>>

剖析树基本方法就这些，还有其他一些，以及如何配合正则表达式。具体请看官方文档

3.2 BeautifulSoup.NavigableString对象方法

NavigableString 对象方法比较简单，获取其内容

>>> soup.title
<title>Page title</title>
>>> title = soup.title.next
>>> title
u'Page title'
>>> type(title)
<class 'BeautifulSoup.NavigableString'>
>>> title.string
u'Page title'

至于如何遍历树，进而分析文档，已经 XML 文档的分析方法，可以参考官方文档。

posted on 2015-06-03 16:35 字符串阅读(397) 评论(0) 编辑收藏举报

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findAll(name, attrs, recursive, text, limit, **kwargs)

`findAll(`name, attrs, recursive, text, limit, **kwargs)