[基础]-beautifulsoup模块使用详解
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。
更多详情参阅中文文档：https://beautifulsoup.readthedocs.io/zh_CN/v4.4.0/
目录
安装：
使用示例：
1. name，标签名称
2. attr，标签属性
3. children,所有子标
4. children,所有子子孙孙标签
5. clear,将标签的所有子标签全部清空（保留标签名）
6. decompose,递归的删除所有的标签
7. extract,递归的删除所有的标签，并获取删除的标签
8. decode,转换为字符串（含当前标签）；decode_contents（不含当前标签）
9. encode,转换为字节（含当前标签）；encode_contents（不含当前标签）
10. find,获取匹配的第一个标签
11. find_all,获取匹配的所有标签
12. has_attr,检查标签是否具有该属性
13. get_text,获取标签内部文本内容
14. index,检查标签在某标签中的索引位置
15. is_empty_element,是否是空标签(是否可以是空)或者自闭合标签，
16. 当前的关联标签
17. 查找某标签的关联标签
18. select,select_one, CSS选择器
19. 标签的内容
20.append在当前标签内部追加一个标签
21.insert在当前标签内部指定位置插入一个标签
22. insert_after,insert_before 在当前标签后面或前面插入
23. replace_with 在当前标签替换为指定标签
24. 创建标签之间的关系
25. wrap，将指定标签把当前标签包裹起来
26. unwrap，去掉当前标签，将保留其包裹的标签
from bs4 import BeautifulSoup
html_doc = """
The Dormouse's story
asdf
The Dormouse's story总共
f
Once upon a time there were three little sisters; and their names were
Elsfie,
Lacie and
Tillie;
and they lived at the bottom of a well.
ad
sf
...
"""
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')安装：
pip3 install beautifulsoup4使用示例：
from bs4 import BeautifulSoup
html_doc = """
The Dormouse's story
...
"""
soup = BeautifulSoup(html_doc, features="lxml")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. attr，标签属性
tag = soup.find('a')
attrs = tag.attrs # 获取
print(attrs)
tag.attrs = {'ik':123} # 设置
tag.attrs['id'] = 'iiiii' # 设置
print(soup)3. children,所有子标
body = soup.find('body')
v = body.children4. children,所有子子孙孙标签
body = soup.find('body')
v = body.descendants5. 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(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')
# 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('id')
# 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
# soup.next
# soup.next_element
# soup.next_elements
# soup.next_sibling
# soup.next_siblings
#
# tag.previous
# tag.previous_element
# tag.previous_elements
# tag.previous_sibling
# tag.previous_siblings
#
# tag.parent
# tag.parents17. 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_all18. 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)========================================end 木风卜雨========================================
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