Python爬虫网安-beautiful soup+示例

目录

beautiful soup:

解析器：

节点选择器：

嵌套选择：

关联选择：

子节点：

子孙节点：

父节点：

祖先节点：

兄弟节点：

上一个兄弟节点：

下一个兄弟节点：

后面所有的兄弟节点：

前面所有的兄弟节点：

方法选择器：

CSS选择器：

---

beautiful soup:

bs4
用于解析html and xml文档
解析器：html.parser、lxml解析器和XML的内置解析器
文档遍历：跟xpath差不多，也是整理成树形结构
搜索：find（） find_all()
修改：增删改查bs4都支持
提取数据
处理特殊字符

解析器：

html.parser（内置） 还行
lxml 速度比较快
xml  速度比较快 
html5lib 用的比较少   速度慢

pip install bs4

#导入 beautiful soup库
from bs4 import BeautifulSoup

#创建一个BeautifulSoup对象，用于解析html文档
soup = BeautifulSoup('
hello
','lxml')

print(soup.p.string)

from bs4 import BeautifulSoup

html = """


The Dormouse's story
Once upon a time there were three little sisters; and their names were
,
Lacie and
Tillie;
and they lived at the bottom of a well.
...

"""

soup = BeautifulSoup(html,'lxml')
#使用prettify（）
print(soup.prettify())

节点选择器：

直接调用节点名既可选择该节点。
如果有多个标签，使用标签名来打印该节点的话，就是打印第一个
类型：

属性：
name:表示标签的名字

from bs4 import BeautifulSoup

html = """


The Dormouse's story
Once upon a time there were three little sisters; and their names were
,
Lacie and
Tillie;
and they lived at the bottom of a well.
...
"""

soup = BeautifulSoup(html,'lxml')
#选择html文档中的title标签
# print(soup.title)
#打印标签下的文本内容
# print(soup.title.string)
# print(soup.head)

# print(soup.p)

#查看数据类型
# print(type(soup.title))
#用name属性获取节点的名称
# print(soup.head.name)
#获取属性 id class
#attrs
# print(soup.p.attrs)
# print(soup.p.attrs['name'])

print(soup.p['name'])
print(soup.p['class'])

嵌套选择：

返回，可以继续下一步的选择

from bs4 import BeautifulSoup

html = """


"""

soup = BeautifulSoup(html,'lxml')

#打印 html文档里面的 title标签
print(soup.head.title)
print(type(soup.head.title))
print(soup.head.title.string)

关联选择：

有时候我们选择的时候不能一部到位，需要先选择某节点，然后选择 他的 父节点，子节点

子节点：

soup.p.children

子孙节点：

soup.p.descendants

from bs4 import BeautifulSoup

html = """

    
        
    
    
        

            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.
        
        
...
"""

soup = BeautifulSoup(html,'lxml')
#输出一个列表，里面包含p节点的所有子节点 包括文本
# print(soup.p.contents)

# print(soup.p.children)
# for i,child in enumerate(soup.p.children):
#     # print(i)
#     print(child)
#打印所有的子孙节点
print(soup.p.descendants)
for i, child in enumerate(soup.p.descendants):
    print(i, child)

父节点：

soup.a.parent

祖先节点：

soup.a.parents

from bs4 import BeautifulSoup

html = """

    
        
    
    
        

            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.
        
        
...
"""

soup = BeautifulSoup(html,'lxml')
#打印父节点
# print(soup.a.parent)
#打印祖先节点：
print(soup.a.parents)
print(list(enumerate(soup.a.parents)))

兄弟节点：

上一个兄弟节点：

soup.a.previous_sibling

下一个兄弟节点：

soup.a.next_sibling

后面所有的兄弟节点：

soup.a.next_siblings

前面所有的兄弟节点：

soup.a.previous_siblings

from bs4 import BeautifulSoup

html = """

    
        

            Once upon a time there were three little sisters; and their names were
            
                Elsie
            
            Hello
            Lacie
            and
            Tillie
            and they lived at the bottom of a well.
        
    
"""

soup = BeautifulSoup(html,'lxml')
#输出下一个兄弟节点
# print(soup.a.next_sibling)
#输出上一个兄弟节点
# print(soup.a.previous_sibling)
#输出所有后续的兄弟节点：
# print(list(enumerate(soup.a.next_siblings)))
#输出所有前面的兄弟节点：
print(list(enumerate(soup.a.previous_siblings)))

from bs4 import BeautifulSoup

html = """

    
        

            Once upon a time there were three little sisters; and their names were
            BobLacie
        
"""
soup = BeautifulSoup(html,'lxml')
print(soup.a.next_sibling.string)

# print(soup.a.parents)
# print(list(soup.a.parents)[0])
print(list(soup.a.parents)[0].attrs['class'])

方法选择器：

find_all,
find方法

from bs4 import BeautifulSoup

html = """

    

        
Hello
    
    

        

            
Foo
            
Bar
            
Jay
        
        

            
Foo
            
Bar
        
    

"""

soup = BeautifulSoup(html,'lxml')

#查找所有的ul元素
# print(soup.find_all(name='ul'))
print(type(soup.find_all(name='ul')[1]))

#遍历所有的ul
for ul in soup.find_all(name='ul'):
    #打印所有ul下的li元素
    # print(type(ul.find_all(name='li')))
    for li in ul.find_all(name='li'):
        print(li.string)

from bs4 import BeautifulSoup

html = """

    

        
Hello
    
    

        

            
Foo
            
Bar
            
Jay
        
        

            
Foo
            
Bar
        
    

"""

soup = BeautifulSoup(html,'lxml')
#使用find_all查询所有既有id属性为'list-2'的元素
print(soup.find_all(attrs={'id':'list-2'}))

# print(soup.find_all(attrs={'class':'element'}))
print(soup.find_all(class_='element'))

from bs4 import BeautifulSoup
import re

html = """

    

        Hello, this is a link
        Hello, this is a link, too
    
"""

soup = BeautifulSoup(html,'lxml')
#使用正则表达式查询所有带有link的标签
found_elements = soup.find_all(string=re.compile('link'))
print(found_elements)

from bs4 import BeautifulSoup

html = """

    

        
Hello
    
    

        

            
Foo
            
Bar
            
Jay
        
        

            
Foo
            
Bar
        
    

"""

soup = BeautifulSoup(html,'lxml')
ul_tag = soup.find(name='ul')
print(ul_tag)

# list_element = soup.find(class_='list')
# print(list_element)

CSS选择器：

调用select方法，传入对应的css

from bs4 import BeautifulSoup

html = """

    

        
Hello
    
    

        

            
Foo
            
Bar
            
Jay
        
        

            
Foo
            
Bar
        
    

"""

soup = BeautifulSoup(html,'lxml')

# print(soup.select('.panel .panel-heading'))

# print(soup.select('ul li'))

# print(soup.select('#list-2 .element'))

# for ul in soup.select('ul'):
#     # print(ul.select('li'))
#     # print(ul['id'])
#     print(ul.attrs['id'])

for li in soup.select('li'):
    # print(li.string)
    print(li.get_text())