[TOC]
# 使用Beautiful Soup
## 1.說明
BeautifulSoup 就是 Python 的一個 HTML 或 XML 的解析庫，我們可以用它來方便地從網頁中提取數據
## 2. 解析器
BeautifulSoup 支持的解析器及優缺點
| 解析器 | 使用方法 | 優勢 | 劣勢 |
| --- | --- | --- | --- |
| Python標準庫 | BeautifulSoup(markup, "html.parser") | Python的內置標準庫、執行速度適中 、文檔容錯能力強 | Python 2.7.3 or 3.2.2)前的版本中文容錯能力差 |
| LXML HTML 解析器 | BeautifulSoup(markup, "lxml") | 速度快、文檔容錯能力強 | 需要安裝C語言庫 |
| LXML XML 解析器 | BeautifulSoup(markup, "xml") | 速度快、唯一支持XML的解析器 | 需要安裝C語言庫 |
| html5lib | BeautifulSoup(markup, "html5lib") | 最好的容錯性、以瀏覽器的方式解析文檔、生成 HTML5 格式的文檔 | 速度慢、不依賴外部擴展 |
## 3.基本使用
實例:
~~~text
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.prettify())
print(soup.title.string)
~~~
運行結果:
~~~text
<html>
<head>
<title>
The Dormouse's story
</title>
</head>
<body>
<p class="title" name="dromouse">
<b>
The Dormouse's story
</b>
</p>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<!-- Elsie -->
</a>
,
<a class="sister" href="http://example.com/lacie" id="link2">
Lacie
</a>
and
<a class="sister" href="http://example.com/tillie" id="link3">
Tillie
</a>
;
and they lived at the bottom of a well.
</p>
<p class="story">
...
</p>
</body>
</html>
The Dormouse's story
~~~
* prettify():把要解析的字符串以標準的縮進格式輸出
* soup.title.string:選擇HTML中的title節點，再調用string屬性得到里面的文本
## 4. 節點選擇器
### 選擇元素
例子:
~~~text
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.title)
print(type(soup.title))
print(soup.title.string)
print(soup.head)
# 只能選擇第一個p節點
print(soup.p)
~~~
運行結果：
~~~text
<title>The Dormouse's story</title>
<class 'bs4.element.Tag'>
The Dormouse's story
<head><title>The Dormouse's story</title></head>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
~~~
### 提取信息
#### 獲取名稱
可以利用 name 屬性來獲取節點的名稱
實例:選擇title，調用name屬性得到節點的名稱
~~~text
print(soup.title.name)
~~~
運行結果:
~~~text
title
~~~
#### 獲取屬性
調用 attrs 獲取所有屬性
~~~text
# 返回字典
print(soup.p.attrs)
print(soup.p.attrs['name'])
~~~
運行結果:
~~~text
{'class': ['title'], 'name': 'dromouse'}
dromouse
~~~
#### 獲取內容 {#獲取內容}
利用 string 屬性獲取節點元素包含的文本內容
~~~text
print(soup.p.string)
~~~
運行結果:
~~~text
The Dormouse's story
~~~
### 嵌套選擇
實例：獲取head節點內部的title節點
~~~text
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.head.title)
print(type(soup.head.title))
print(soup.head.title.string)
~~~
運行結果:
~~~text
<title>The Dormouse's story</title>
<class 'bs4.element.Tag'>
The Dormouse's story
~~~
### 關聯選擇
#### 子節點和子孫節點
獲取直接子節點可以調用 contents 屬性
實例:獲取body節點下子節點p
~~~text
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">
<span>Elsie</span>
</a>
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a>
and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>
and they lived at the bottom of a well.
</p>
<p class="story">...</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.body.contents)
~~~
運行結果:返回結果是列表形式
~~~text
['\n', <p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
and
<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
and they lived at the bottom of a well.
</p>, '\n', <p class="story">...</p>, '\n']
~~~
可以調用 children 屬性，得到相應的結果:
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.body.children)
for i,child in enumerate(soup.body.children):
print(i,child)
~~~
運行結果:
~~~text
<list_iterator object at 0x00000217D33CD048>
0
1 <p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
and
<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
and they lived at the bottom of a well.
</p>
2
3 <p class="story">...</p>
4
~~~
要得到所有的子孫節點的話可以調用 descendants 屬性
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.body.descendants)
for i,child in enumerate(soup.body.descendants):
print(i,child)
~~~
運行結果:
~~~text
<generator object descendants at 0x0000014D106353B8>
0
1 <p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
and
<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
and they lived at the bottom of a well.
</p>
2
Once upon a time there were three little sisters; and their names were
3 <a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
4
5 <span>Elsie</span>
6 Elsie
7
8
9 <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
10 Lacie
11
and
12 <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>
13 Tillie
14
and they lived at the bottom of a well.
15
16 <p class="story">...</p>
17 ...
18
~~~
#### 父節點和祖先節點
要獲取某個節點元素的父節點，可以調用 parent 屬性：
實例:獲取節點a的父節點p下的內容
~~~text
html = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">
<span>Elsie</span>
</a>
</p>
<p class="story">...</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.a.parent)
~~~
運行結果:
~~~text
<p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
~~~
要想獲取所有的祖先節點，可以調用 parents 屬性
~~~text
html = """
<html>
<body>
<p class="story">
<a href="http://example.com/elsie" class="sister" id="link1">
<span>Elsie</span>
</a>
</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(type(soup.a.parents))
print(list(enumerate(soup.a.parents)))
~~~
運行結果:
~~~text
<class 'generator'>
[(0, <p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>), (1, <body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body>), (2, <html>
<body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body></html>), (3, <html>
<body>
<p class="story">
<a class="sister" href="http://example.com/elsie" id="link1">
<span>Elsie</span>
</a>
</p>
</body></html>)]
~~~
#### 兄弟節點
* next\_sibling :獲取節點的下一個兄弟節點
* previous\_sibling:獲取節點上一個兄弟節點
* next\_siblings :返回所有前面兄弟節點的生成器
* previous\_siblings :返回所有后面的兄弟節點的生成器
實例:
~~~text
html = """
<html>
<body>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">
<span>Elsie</span>
</a>
Hello
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a>
and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>
and they lived at the bottom of a well.
</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print('next sibling:',soup.a.next_sibling)
print('previous sibling:',soup.a.previous_sibling)
print("next siblings:",list(soup.a.next_siblings))
print("previouos siblings:",list(soup.a.previous_siblings))
~~~
運行結果:
~~~text
next sibling:
Hello
previous sibling:
Once upon a time there were three little sisters; and their names were
next siblings: ['\n Hello\n ', <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, ' \n and\n ', <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>, '\n and they lived at the bottom of a well.\n ']
previouos siblings: ['\n Once upon a time there were three little sisters; and their names were\n ']
~~~
#### 提取信息 {#提取信息}
獲取一些信息，比如文本、屬性等等
~~~text
html = """
<html>
<body>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Bob</a><a href="http://example.com/lacie" class="sister" id="link2">Lacie</a>
</p>
"""
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print('Next Sibling:')
print(type(soup.a.next_sibling))
print(soup.a.next_sibling)
print(soup.a.next_sibling.string)
print('Parent:')
print(type(soup.a.parents))
print(list(soup.a.parents)[0])
print(list(soup.a.parents)[0].attrs['class'])
~~~
運行結果:
~~~text
Next Sibling:
<class 'bs4.element.Tag'>
<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
Lacie
Parent:
<class 'generator'>
<p class="story">
Once upon a time there were three little sisters; and their names were
<a class="sister" href="http://example.com/elsie" id="link1">Bob</a><a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>
</p>
['story']
~~~
## 5. 方法選擇器
常用查詢方法:find\_all()、find()
### find\_all()
查詢所有符合條件的元素
語法:
~~~text
find_all(name , attrs , recursive , text , **kwargs)
~~~
#### name
根據節點名來查詢元素
~~~text
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.find_all(name='ul'))
print(type(soup.find_all(name='ul')[0]))
~~~
運行結果:返回結果類型為:bs4.element.Tag
~~~text
[<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>, <ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>]
<class 'bs4.element.Tag'>
~~~
獲取ul下的li節點以及li下的文本內容
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# print(soup.find_all(name='ul'))
# print(type(soup.find_all(name='ul')[0]))
for ul in soup.find_all(name='ul'):
print(ul.find_all(name='li'))
for li in ul.find_all(name='li'):
print(li.string)
~~~
運行結果:
~~~text
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
Foo
Bar
Jay
[<li class="element">Foo</li>, <li class="element">Bar</li>]
Foo
Bar
~~~
#### attrs
根據屬性來進行查詢
~~~text
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# 查詢屬性以字典的的進行查詢
print(soup.find_all(attrs={'id':'list-1'}))
print(soup.find_all(attrs={"name":"elements"}))
~~~
運行結果:
~~~text
[<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
[<ul class="list" id="list-1" name="elements">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
~~~
對于常用的屬性比如id，class，可以不用attrs傳遞
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(id='list-1'))
# 由于class是關鍵字需要添加下劃線區分
print(soup.find_all(class_='element'))
~~~
運行結果:
~~~text
[<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]
~~~
#### text
text 參數可以用來匹配節點的文本，傳入的形式可以是字符串，可以是正則表達式對象
~~~text
html='''
<div class="panel">
<div class="panel-body">
<a>Hello, this is a link</a>
<a>Hello, this is a link, too</a>
</div>
</div>
'''
import re
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
# 查詢文本包含有link的文本
print(soup.find_all(text=re.compile('link')))
~~~
運行結果:
~~~text
['Hello, this is a link', 'Hello, this is a link, too']
~~~
### find()
find() 方法返回的是單個元素，即第一個匹配的元素，而 find\_all() 返回的是所有匹配的元素組成的列表
~~~text
html='''
<div class="panel">
<div class="panel-body">
<a class='element'>Hello, this is a link</a>
<a class='element'>Hello, this is a link, too</a>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.find(name='a'))
print(soup.find(attrs={'class':'element'}))
print(soup.find(class_='element'))
print(type(soup.find(name='a')))
~~~
返回結果:返回類型為
~~~text
<a class="element">Hello, this is a link</a>
<a class="element">Hello, this is a link</a>
<a class="element">Hello, this is a link</a>
<class 'bs4.element.Tag'>
~~~
其他查詢方法
### find\_parents() find\_parent()
find\_parents() 返回所有祖先節點，find\_parent() 返回直接父節點。
### find\_next\_siblings() find\_next\_sibling()
find\_next\_siblings() 返回后面所有兄弟節點，find\_next\_sibling() 返回后面第一個兄弟節點。
### find\_previous\_siblings() find\_previous\_sibling()
find\_previous\_siblings() 返回前面所有兄弟節點，find\_previous\_sibling() 返回前面第一個兄弟節點。
### find\_all\_next() find\_next()
find\_all\_next() 返回節點后所有符合條件的節點, find\_next() 返回第一個符合條件的節點。
### find\_all\_previous() 和 find\_previous()
find\_all\_previous() 返回節點后所有符合條件的節點, find\_previous() 返回第一個符合條件的節點
## 6.CSS選擇器
相關鏈接:[http://www.w3school.com.cn/cssref/css\_selectors.asp](http://www.w3school.com.cn/cssref/css_selectors.asp)。
使用 CSS 選擇器，只需要調用 select() 方法，傳入相應的 CSS 選擇器
實例:
~~~text
html='''
<div class="panel">
<div class="panel-heading">
<h4>Hello</h4>
</div>
<div class="panel-body">
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
<ul class="list list-small" id="list-2">
<li class="element">Foo</li>
<li class="element">Bar</li>
</ul>
</div>
</div>
'''
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
print(soup.select('.panel .panel-heading'))
print(soup.select('ul li'))
print(soup.select('#list-2 .element'))
print(soup.select('ul')[0])
~~~
運行結果:
~~~text
[<div class="panel-heading">
<h4>Hello</h4>
</div>]
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>, <li class="element">Foo</li>, <li class="element">Bar</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
<ul class="list" id="list-1">
<li class="element">Foo</li>
<li class="element">Bar</li>
<li class="element">Jay</li>
</ul>
~~~
### 嵌套選擇
實例:select() 方法同樣支持嵌套選擇，例如我們先選擇所有 ul 節點，再遍歷每個 ul 節點選擇其 li 節點
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
for ul in soup.select('ul'):
print(ul.select('li'))
~~~
運行結果:
~~~text
[<li class="element">Foo</li>, <li class="element">Bar</li>, <li class="element">Jay</li>]
[<li class="element">Foo</li>, <li class="element">Bar</li>]
~~~
### 獲取屬性
獲取屬性還是可以用上面的方法獲取
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
for ul in soup.select('ul'):
print(ul['id'])
print(ul.attrs['id'])
~~~
運行結果:
~~~text
list-1
list-1
list-2
list-2
~~~
### 獲取文本
獲取文本可以用string 屬性，還有一種方法那就是 get\_text()，同樣可以獲取文本值。
~~~text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html,'lxml')
for li in soup.select('li'):
print('GET TEXT:',li.get_text())
print('STRING:',li.string)
~~~
運行結果:
~~~text
GET TEXT: Foo
STRING: Foo
GET TEXT: Bar
STRING: Bar
GET TEXT: Jay
STRING: Jay
GET TEXT: Foo
STRING: Foo
GET TEXT: Bar
STRING: Bar
~~~
## 7.細節
* 推薦使用 LXML 解析庫，必要時使用 html.parser
* 節點選擇篩選功能弱但是速度快
* 建議使用 find()、find\_all() 查詢匹配單個結果或者多個結果
* 如果對 CSS 選擇器熟悉的話可以使用 select() 選擇法
如何匹配規則不是熟練，而且想快速獲取，可以如下操作:
右鍵能手敲就手敲，不要偷懶，不然能力提升不上去
