目录：Python网络爬虫实战系列
- Python网络爬虫实战之一：网络爬虫理论基础
- Python网络爬虫实战之二：环境部署、基础语法、文件操作
- Python网络爬虫实战之三：基本工具库urllib和requests
- Python网络爬虫实战之四：BeautifulSoup
- Python网络爬虫实战之五：正则表达式
- Python网络爬虫实战之六：静态网页爬取案例实战
- Python网络爬虫实战之七：动态网页爬取案例实战 Selenium + PhantomJS
- Python网络爬虫实战之八：动态网页爬取案例实战 Selenium + Headless Chrome
- Python网络爬虫实战之九：Selenium进阶操作与爬取京东商品评论
- Python网络爬虫实战之十：利用API进行数据采集
- Python网络爬虫实战之十一：Scrapy爬虫框架入门介绍
- Python网络爬虫实战之十二：Scrapy爬虫三个实战小案例
- Python网络爬虫实战之十三：Scrapy爬取名侦探柯南漫画集
- Python网络爬虫实战之十四：Scrapy结合scrapy-splash爬取动态网页数据
正文：
Beautiful Soup 是一个可以从HTML或XML文件中提取数据的Python库.它能够通过你喜欢的转换器实现惯用的文档导航,查找,修改文档的方式.Beautiful Soup会帮你节省数小时甚至数天的工作时间.
安装: pip install beautifulsoup4
名字是beautifulsoup 的包,是 Beautiful Soup3 的发布版本,因为很多项目还在使用BS3, 所以 beautifulsoup 包依然有效.但是如果你在编写新项目,那么你应该安装的 beautifulsoup4，这个包兼容Python2和Python3
BeautifulSoup的基础使用
下面的一段HTML代码将作为例子被多次用到.这是《爱丽丝梦游仙境》的的一段内容(以后简称文档)
html_doc = """
The Dormouse's story
The Dormouse's story
Once upon a time there were three little sisters; and their names were
Elsie,
Lacie and
Tillie;
and they lived at the bottom of a well.
...
"""
使用BeautifulSoup解析这段代码,能够得到一个 BeautifulSoup 的对象,并能按照标准的缩进格式的结构输出
from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, "lxml")
print(soup.prettify())
# result:
#
#
#
# The Dormouse's story
#
#
#
#
#
# The Dormouse's story
#
#
#
# Once upon a time there were three little sisters; and their names were
#
# Elsie
#
# ,
#
# Lacie
#
# and
#
# Tillie
#
# ;
# and they lived at the bottom of a well.
#
#
# ...
#
#
#
几个简单的浏览结构化数据的方法
soup.title
# result: The Dormouse's story
soup.title.name
# result: 'title'
soup.title.string
# result: 'The Dormouse's story'
soup.title.text
# result: 'The Dormouse's story'
soup.title.parent.name
# result: 'head'
soup.p
# result: The Dormouse's story
soup.p['class']
# result: 'title'
soup.a
# result: Elsie
soup.find_all('a')
# result:
# [Elsie,
# Lacie,
# Tillie]
soup.find(id="link3")
# result: Tillie
从文档中找到所有标签的链接
for link in soup.find_all('a'):
print(link.get('href'))
# result:
# http://example.com/elsie
# http://example.com/lacie
# http://example.com/tillie
从文档中获取所有文字内容
print(soup.get_text())
# result:
# The Dormouse's story
#
# The Dormouse's story
#
# Once upon a time there were three little sisters; and their names were
# Elsie,
# Lacie and
# Tillie;
# and they lived at the bottom of a well.
#
# ...
从文档中解析导航树
# 直接子节点
print(soup.body.contents)
for child in soup.descendants:
print(child)
# 所有后代节点
for child in soup.descendants:
print(child)
# 节点内容1-包含换行符
for string in soup.strings:
print(repr(string))
# 节点内容2-不包含换行符
for string in soup.stripped_strings:
print(repr(string))
# 兄弟节点(没有一个兄弟节点会返回None)
print(soup.p.next_sibling)
print(soup.p.previous_sibling)
for sibling in soup.a.next_siblings:
print(repr(sibling))
# 前后节点
print(soup.head.next_element)
print(soup.head.previous_element)
# 父节点
from urllib.request import urlopen
html = urlopen("http://www.pythonscraping.com/pages/page3.html")
bsObj = BeautifulSoup(html)
print(bsObj.find("img", {"src": "../img/gifts/img1.jpg"}).parent.previous_sibling.get_text())
从文档中解析CSS选择器
print(soup.select('title'))
print(soup.select('a'))
print(soup.select('b'))
print(soup.select('.sisiter'))
print(soup.select('#link1'))
print(soup.select('p #link1'))
print(soup.select('head > title'))
print(soup.select('a[class="sister"]'))
print(soup.select('a[href="http://example.com/elsie"]'))
print(soup.select('p a[href="http://example.com/elsie"]'))
结合正则表达式或其他逻辑条件
import re
for tag in soup.find_all(href=re.compile("elsie")):
print(tag)
# result: Elsie
for tag in soup.find_all("a", class_="sister"):
print(tag)
# result：
# Elsie
# Lacie
# Tillie
for tag in soup.find_all(["a", "b"]):
print(tag)
# result :
# The Dormouse's story
# Elsie
# Lacie
# Tillie
for tag in soup.find_all(True):
print(tag)
# result:
# The Dormouse's story
#
# The Dormouse's story
# Once upon a time there were three little sisters; and their names were
# Elsie,
# Lacie and
# Tillie;
# and they lived at the bottom of a well.
# ...
#
# The Dormouse's story
# The Dormouse's story
#
# The Dormouse's story
# Once upon a time there were three little sisters; and their names were
# Elsie,
# Lacie and
# Tillie;
# and they lived at the bottom of a well.
# ...
#
# The Dormouse's story
# The Dormouse's story
# Once upon a time there were three little sisters; and their names were
# Elsie,
# Lacie and
# Tillie;
# and they lived at the bottom of a well.
# Elsie
# Lacie
# Tillie
# ...
def has_class_but_no_id(tag):
return tag.has_attr('class') and not tag.has_attr('id')
for tag in soup.find_all(has_class_but_no_id):
print(tag)
# result:
# The Dormouse's story
# Once upon a time there were three little sisters; and their names were
# Elsie,
# Lacie and
# Tillie;
# and they lived at the bottom of a well.
# ...
BeautifulSoup的主要参数的使用
html_doc = """
The Dormouse's story
The Dormouse's story
Once upon a time there were three little sisters; and their names were
Elsie,
Lacie and
Tillie;
and they lived at the bottom of a well.
...
"""
import bs4
from bs4 import BeautifulSoup
soup = BeautifulSoup(html_doc, "lxml")
# text参数
soup.find_all(text="Elsie")
soup.find_all(text=["Elsie", "Lacie", "Tillie"])
soup.find_all(text=re.compile("Dormouse"))
# limit参数
soup.find_all("a", limit=2)
# recursive参数
soup.html.find_all("title")
soup.html.find_all("title", recursive=False)
# tag对象
print(soup.title)
print(soup.head)
print(soup.a)
print(soup.p)
print(type(soup.a))
print(soup.name)
print(soup.head.name)
print(soup.p.attrs)
print(soup.p['class'])
print(soup.p.get('class'))
soup.p['class'] = "newclass"
print(soup.p)
del soup.p['class']
print(soup.p)
# NavigableString对象
print(soup.p.string)
print(type(soup.p.string))
# BeautifulSoup对象
print(type(soup.name))
print(soup.name)
print(soup.attrs)
# Comment对象
print(soup.a)
print(soup.a.string)
print(type(soup.a.string))
if type(soup.a.string) == bs4.element.Comment:
print(soup.a.string)
BeautifulSoup解析在线网页实例
from urllib.request import urlopen
from bs4 import BeautifulSoup
html = urlopen('http://www.pythonscraping.com/exercises/exercise1.html')
bsObj = BeautifulSoup(html.read(), 'lxml')
print(bsObj.h1)
# CSS属性
from urllib.request import urlopen
from bs4 import BeautifulSoup
html = urlopen('http://www.pythonscraping.com/pages/warandpeace.html')
bsObj = BeautifulSoup(html, 'lxml')
nameList = bsObj.findAll('span', {'class': 'green'})
for name in nameList:
print(name.get_text())
# find()和findall()
from urllib.request import urlopen
from bs4 import BeautifulSoup
html = urlopen('http://www.pythonscraping.com/pages/warandpeace.html')
bsObj = BeautifulSoup(html)
allText = bsObj.findAll(id='text')
print(allText[0].get_text())
更多使用方法参见BeautifulSoup 中文文档