Bs4安装与使用
bs4安装配置:
```python
pip install bs4在终端中下载bs4解析库
pip install lxml
在终端中下载lxml库
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1. 创建解析对象
2. ```python
from bs4 import BeautifulSoup
f = open('../day01/baidu.html','r',encoding='utf8')
soup = BeautifulSoup(f,features='lxml')
print(soup.div)要注意的是,soup.TagName返回的是第一个对应的标签的内容,
```python
from bs4 import BeautifulSoupf = open(‘../day01/baidu.html’,’r’,encoding=’utf8’)
soup = BeautifulSoup(f,features=’lxml’)
print(soup.find(‘div’))
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5. soup.find('TagName')所返回的,同样是第一个元素,其效果和soup.TagName基本相同
6. ```python
from bs4 import BeautifulSoup
f = open('../day01/baidu.html','r',encoding='utf8')
soup = BeautifulSoup(f,features='lxml')
print(soup.find('div',class_ = 'op-short-video-pc-poster c-span6'))find方法的属性:class_ 设定的是目标的class名,只有符合条件的TagName才能被查询出来
```python
from bs4 import BeautifulSoupf = open(‘../day01/baidu.html’,’r’,encoding=’utf8’)
soup = BeautifulSoup(f,features=’lxml’)
print(soup.find_all(‘div’,class_ = ‘op-short-video-pc-poster c-span6’))
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9. find_all的用法和find基本相同,但是返回的数据格式是一个列表,并且返回的是所有符合条件的数据,而不是第一个
10. ```python
from bs4 import BeautifulSoup
f = open('../day01/baidu.html','r',encoding='utf8')
soup = BeautifulSoup(f,features='lxml')
print(soup.select('.opr-recommends-merge-content'))select方法的用法,参数为选择器,支持标签选择器,层级选择器,id选择器,类选择器
```python
from bs4 import BeautifulSoupf = open(‘../day01/baidu.html’,’r’,encoding=’utf8’)
soup = BeautifulSoup(f,features=’lxml’)
print(soup.select(‘.opr-recommends-merge-content > div > a’))
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13. 层级选择器写法,使用 > 来指向下一级元素
14. 层级选择器如果需要定位子类的子类的话,可以不写 >
15. ```python
from bs4 import BeautifulSoup
f = open('../day01/baidu.html','r',encoding='utf8')
soup = BeautifulSoup(f,features='lxml')
print(soup.select('.opr-recommends-merge-content a'))以上为不指向性获取包含的内容
```python
from bs4 import BeautifulSoupf = open(‘../day01/baidu.html’,’r’,encoding=’utf8’)
soup = BeautifulSoup(f,features=’lxml’)
print(soup.select(‘.cr-title,.c-clearfix span’)[0].span.string)
from bs4 import BeautifulSoup
f = open(‘../day01/baidu.html’,’r’,encoding=’utf8’)
soup = BeautifulSoup(f,features=’lxml’)
print(soup.select(‘.cr-title,.c-clearfix span’)[0].span.text)
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18. text与string均可获取标签中的文字内容
19. text获取的是标签中所有的文本内容,
20. string获取的是标签中的直系文本内容以外的内容无法获取
21. "我的奴隶的奴隶,不是我的奴隶"
22. ```python
from bs4 import BeautifulSoup
f = open('../day01/baidu.html','r',encoding='utf8')
soup = BeautifulSoup(f,features='lxml')
print(soup.select('.cr-title,.c-clearfix span')[0].a['class'])
print(soup.find('div',class_ = 'op-short-video-pc-poster c-span6').a['class'])
print(soup.find_all('div',class_ = 'op-short-video-pc-poster c-span6')[0].a['class'])通过定位获取属性值
