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Python爬虫入门BeautifulSoup模块

奋斗De奶爸 2022-02-17 阅读 51


BeautifulSoup

BeautifulSoup是一个模块,该模块用于接收一个HTML或XML字符串,

然后将其进行格式化,之后遍可以使用他提供的方法进行快速查找指定元素,

从而使得在HTML或XML中查找指定元素变得简单。

安装:

pip install BeautifulSoup4

导入:

from bs4 import BeautifulSoup

beautifulsoup简单示例:

soup = BeautifulSoup(text, features="html.parser")

# 返回第一个对象
v1 = soup.find("div")
v1 = soup.find(id="i1")
v1 = soup.find("div", id="i1") # 组合使用

# 返回对象列表
v2 = soup.find_all("div")
v2 = soup.find_all(id="i1")
v2 = soup.find_all("div", id="i1") # 组合使用

tag.text # 获取文本
tag.attrs("href") # 获取属性

代码示例

from bs4 import BeautifulSoup

html_doc = """
<html>
<head>
<title>The Dormouse's story</title>
</head>
<body>
asdf
<div class="title">
<b>The Dormouse's story总共</b>
<h1>f</h1>
</div>
<div class="story">Once upon a time there were three little sisters; and their names were
<a class="sister0" id="link1">Els<span>f</span>ie</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.</div>
ad<br/>sf
<p class="story">...</p>
</body>
</html>
"""

soup = BeautifulSoup(html_doc, features="lxml")

# 找到第一个a标签
tag1 = soup.find(name='a')

# 找到所有的a标签
tag2 = soup.find_all(name='a')

# 找到id=link2的标签
tag3 = soup.select('#link2')

1、 name,标签名称

tag = soup.find('a')
name = tag.name # 获取
print(name)

tag.name = 'span' # 设置
print(soup)

2、 attrs,标签属性

tag = soup.find('a')
attrs = tag.attrs # 获取
print(attrs)

tag.attrs = {'ik':123} # 设置
tag.attrs['id'] = 'value' # 设置
print(soup)

3、 children,所有子标签

body = soup.find('body')
v = body.children

4、 descendants,所有子子孙孙标签

body = soup.find('body')
v = body.descendants

5、 clear,将标签的所有子标签全部清空(保留标签名)

tag = soup.find('body')
tag.clear()
print(soup)

6、decompose,递归的删除所有的标签

body = soup.find('body')
body.decompose()
print(soup)

7、extract,递归的删除所有的标签,并获取删除的标签

body = soup.find('body')
v = body.extract()
print(soup)

8、 decode,转换为字符串(含当前标签);decode_contents(不含当前标签)

body = soup.find('body')
v = body.decode()
v = body.decode_contents()
print(v)

9、encode,转换为字节(含当前标签);encode_contents(不含当前标签)

body = soup.find('body')
v = body.encode()
v = body.encode_contents()
print(v)

10、find,获取匹配的第一个标签

tag = soup.find('a')
print(tag)
tag = soup.find(name='a', attrs={'class': 'sister'},
recursive=True, text='Lacie')

tag = soup.find(name='a', class_='sister',
recursive=True, text='Lacie')

print(tag)

11、find_all,获取匹配的所有标签

tags = soup.find_all('a')
print(tags)

tags = soup.find_all('a',limit=1)
print(tags)

tags = soup.find_all(name='a', attrs={'class': 'sister'},
recursive=True, text='Lacie')

tags = soup.find_all(name='a', class_='sister',
recursive=True, text='Lacie')

print(tags)


####### 列表 #######
v = soup.find_all(name=['a','div'])
print(v)

v = soup.find_all(class_=['sister0', 'sister'])
print(v)

v = soup.find_all(text=['Tillie'])
print(v, type(v[0]))


v = soup.find_all(id=['link1','link2'])
print(v)

v = soup.find_all(href=['link1','link2'])
print(v)

####### 正则 #######
import re
rep = re.compile('p')
rep = re.compile('^p') # 所有以p开头
v = soup.find_all(name=rep)
print(v)

rep = re.compile('sister.*')
v = soup.find_all(class_=rep)
print(v)

rep = re.compile('http://www.oldboy.com/static/.*')
v = soup.find_all(href=rep)
print(v)

####### 方法筛选 #######
def func(tag):
return tag.has_attr('class') and tag.has_attr('id')

v = soup.find_all(name=func)
print(v)


## get,获取标签属性
tag = soup.find('a')
v = tag.get('id')
print(v)

12、has_attr,检查标签是否具有该属性

tag = soup.find('a')
v = tag.has_attr('id')
print(v)

13、get_text,获取标签内部文本内容

tag = soup.find('a')
v = tag.get_text()
print(v)

14、index,检查标签在某标签中的索引位置

tag = soup.find('body')
v = tag.index(tag.find('div'))
print(v)

tag = soup.find('body')
for i, v in enumerate(tag):
print(i,v)

15、 is_empty_element,是否是空标签(是否可以是空)或者自闭合标签,

# 判断是否是如下标签:
# 'br' , 'hr', 'input', 'img', 'meta','spacer', 'link', 'frame', 'base'

tag = soup.find('br')
v = tag.is_empty_element
print(v)

16、 当前的关联标签

tag.next
tag.next_element
tag.next_elements
tag.next_sibling
tag.next_siblings

tag.previous
tag.previous_element
tag.previous_elements
tag.previous_sibling
tag.previous_siblings

tag.parent
tag.parents

tag.children
tag.descendants

17、查找某标签的关联标签

tag.find_next(...)
tag.find_all_next(...)
tag.find_next_sibling(...)
tag.find_next_siblings(...)

tag.find_previous(...)
tag.find_all_previous(...)
tag.find_previous_sibling(...)
tag.find_previous_siblings(...)

tag.find_parent(...)
tag.find_parents(...)

# 参数同find_all

18、 select,select_one, CSS选择器

soup.select("title")

soup.select("p nth-of-type(3)")

soup.select("body a")

soup.select("html head title")

tag = soup.select("span,a")

soup.select("head > title")

soup.select("p > a")

soup.select("p > a:nth-of-type(2)")

soup.select("p > #link1")

soup.select("body > a")

soup.select("#link1 ~ .sister")

soup.select("#link1 + .sister")

soup.select(".sister")

soup.select("[class~=sister]")

soup.select("#link1")

soup.select("a#link2")

soup.select('a[href]')

soup.select('a[href="http://example.com/elsie"]')

soup.select('a[href^="http://example.com/"]')

soup.select('a[href$="tillie"]')

soup.select('a[href*=".com/el"]')


from bs4.element import Tag

def default_candidate_generator(tag):
for child in tag.descendants:
if not isinstance(child, Tag):
continue
if not child.has_attr('href'):
continue
yield child

tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator)
print(type(tags), tags)

from bs4.element import Tag

def default_candidate_generator(tag):
for child in tag.descendants:
if not isinstance(child, Tag):
continue
if not child.has_attr('href'):
continue
yield child

tags = soup.find('body').select("a", _candidate_generator=default_candidate_generator, limit=1)
print(type(tags), tags)

19、 标签的内容

tag = soup.find('span')
print(tag.string) # 获取
tag.string = 'new content' # 设置
print(soup)

tag = soup.find('body')
print(tag.string)
tag.string = 'xxx'
print(soup)

tag = soup.find('body')
v = tag.stripped_strings # 递归内部获取所有标签的文本
print(v)

20、append在当前标签内部追加一个标签

tag = soup.find('body')
tag.append(soup.find('a'))
print(soup)

from bs4.element import Tag

obj = Tag(name='i',attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('body')
tag.append(obj)
print(soup)

21、insert在当前标签内部指定位置插入一个标签

from bs4.element import Tag

obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('body')
tag.insert(2, obj)
print(soup)

22、 insert_after,insert_before 在当前标签后面或前面插入

from bs4.element import Tag

obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('body')
tag.insert_before(obj)
tag.insert_after(obj)
print(soup)

23、 replace_with 在当前标签替换为指定标签

from bs4.element import Tag

obj = Tag(name='i', attrs={'id': 'it'})
obj.string = '我是一个新来的'
tag = soup.find('div')
tag.replace_with(obj)
print(soup)

24、 创建标签之间的关系

tag = soup.find('div')
a = soup.find('a')
tag.setup(previous_sibling=a)
print(tag.previous_sibling)

25、wrap,将指定标签把当前标签包裹起来

from bs4.element import Tag

obj1 = Tag(name='div', attrs={'id': 'it'})
obj1.string = '我是一个新来的'
tag = soup.find('a')
v = tag.wrap(obj1)
print(soup)

tag = soup.find('a')
v = tag.wrap(soup.find('p'))
print(soup)

26、 unwrap,去掉当前标签,将保留其包裹的标签

tag = soup.find('a')
v = tag.unwrap()
print(soup)


参考:


​​​​

  1. 官方文档:​​​http://beautifulsoup.readthedocs.io/zh_CN/v4.4.0/​​​




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