python爬蟲第六篇--BeautifulSoup庫
阿新 • • 發佈：2018-11-30
BeautifulSoup庫
簡介
-
靈活方便的網頁解析庫，處理高效，支援多種解析器
-
利用它不用編寫正則表示式即可方便地實現網頁資訊的爬取
-
MacOS安裝：
pip3 install BeautifulSoup4(已經更新到4了) -
soup = BeautifulSoup(html, ‘lxml’)
- soup.prettify()
- soup.title
- soup.title.name
- soup.title.string
- soup.head
- soup.head.title.string
- soup.p
- soup.p.string
- soup.p.attrs[‘name’]
- soup.p[‘name’]
- soup.p.children
- soup.p.descendants
- soup.a.parents
- soup.find系列
| 解析器 | 使用方法 | 優勢 | 劣勢 |
|---|---|---|---|
| Python標準庫 | BeautifulSoup(markup, “html.parser”) | Python的內建標準庫、執行速度適中 、文件容錯能力強 | 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、文件容錯能力強 | 需要安裝C語言庫 |
| lxml XML 解析器 | BeautifulSoup(markup, “xml”) | 速度快、唯一支援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件、生成HTML5格式的文件 | 速度慢、不依賴外部擴充套件 |
基本使用
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())#使用補全、容錯等格式化為標準格式
print(soup.title.string)#列印title
標籤選擇器
選擇元素
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.head)
print(soup.p)#只返回第一個結果
獲取名稱
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.name)
獲取屬性
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.p.attrs['name'])
print(soup.p['name'])
獲取內容
html = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p clss="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.p.string)
巢狀選擇
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.head.title.string)
子節點和子孫節點
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.p.contents)
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.p.children)
for i, child in enumerate(soup.p.children):
print(i, child)
# from bs4 import BeautifulSoup
# soup = BeautifulSoup(html, 'lxml')
# print(soup.p.descendants)
# for i, child in enumerate(soup.p.descendants):
# print(i, child)
父節點和祖先節點
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.a.parent)
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(list(enumerate(soup.a.parents)))
兄弟結點
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(list(enumerate(soup.a.next_siblings)))
print(list(enumerate(soup.a.previous_siblings)))
標準選擇器
-
find_all( name , attrs , recursive , text , **kwargs )
可根據標籤名、屬性、內容查詢文件
-
find( name , attrs , recursive , text , **kwargs )
find返回單個元素，find_all返回所有元素
-
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()返回後面所有兄弟節點，find_next_sibling()返回後面第一個兄弟節點
-
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()返回節點後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() find_previous()
find_all_previous()返回節點後所有符合條件的節點, find_previous()返回第一個符合條件的節點
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>
'''
#name
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all('ul'))
print(type(soup.find_all('ul')[0]))
#attrs
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.find_all('ul'):
print(ul.find_all('li'))
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(id='list-1'))
print(soup.find_all(class_='element'))
#text
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find_all(text='Foo'))
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
print(soup.find('ul'))
print(type(soup.find('ul')))
print(soup.find('page'))
CSS選擇器
通過select()直接傳入CSS選擇器即可完成選擇
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(type(soup.select('ul')[0]))
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
print(ul.select('li'))
獲取屬性
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for ul in soup.select('ul'):
print(ul['id'])
print(ul.attrs['id'])
獲取內容
from bs4 import BeautifulSoup
soup = BeautifulSoup(html, 'lxml')
for li in soup.select('li'):
print(li.get_text())
總結
- 推薦使用lxml解析庫，必要時使用html.parser
- 標籤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選擇器熟悉建議使用select()
- 記住常用的獲取屬性和文字值的方法