1. 安装
cmd命令行下，BeautifulSoup的安装：
pip3 install beautifulsoup4
使用下面的网站进行测试：
import requests
vUrl = requests.get("http://python123.io/ws/demo.html")
vUrl.text
'<html><head><title>This is a python demo page</title></head>\r\n<body>\r\n<p class="title"><b>The demo python introduces several python courses.</b></p>\r\n<p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:\r\n<a href="http://www.icourse163.org/course/BIT-268001" class="py1" id="link1">Basic Python</a> and <a href="http://www.icourse163.org/course/BIT-1001870001" class="py2" id="link2">Advanced Python</a>.</p>\r\n</body></html>'
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
print(vSoup.prettify())
<html>
<head>
<title>
This is a python demo page
</title>
</head>
<body>
<p class="title">
<b>
The demo python introduces several python courses.
</b>
</p>
<p class="course">
Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">
Basic Python
</a>
and
<a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">
Advanced Python
</a>
.
</p>
</body>
</html>
2.Beautifulsoup的元素
- Beautiful Soup库解析器：
| 解析器 | 使用方法 | 条件 |
|---|---|---|
| bs4的HTML解析器 | BeautifulSoup(data, "html.parser") | 安装bs4库 |
| lxml的HTML解析器 | BeautifulSoup(data, "lxml") | pip3 install lxml |
| lxml的XML解析器 | BeautifulSoup(data, "xml") | pip3 install lxml |
| html5lib的解析器 | BeautifulSoup(data, "html5lib") | pip3 install html5 |
- Beautiful Soup类的基本元素
| 基本元素 | 说明 |
|---|---|
| Tag | 标签，最基本的单元组织，分别用<>和</>标明开头和结尾 |
| Name | 标签的名字，<p>...</p>，的名字是"p"，格式：<tag>.name |
| Attributes | 标签的属性，字典形式组织，格式：<tag>.attrs |
| NavigableString | 标签内非属性字符串，<>...</>中文字符，格式：<tag>.string |
| Comment | 标签内字符串的注释部分，一种特殊的Comment类型 |
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
vSoup.title # 返回title标签
vTag = vSoup.a # 将a标签存进一个变量中
print(vTag.name) # 返回a的名字
print(vSoup.a.parent.name) # 等同于vTag.parent.name 父结构的名字
print(vSoup.a.parent.parent.name)
print(vTag.attrs) # 获得字典格式的属性内容
print(vTag.attrs["class"]) # 查看class属性
print(vTag.attrs["href"]) # 查看href属性
print(type(vTag.attrs)) # 查看类型
print(type(vTag)) # 查看类型
print(vTag.string)
a
p
body
{'href': 'http://www.icourse163.org/course/BIT-268001', 'class': ['py1'], 'id': 'link1'}
['py1']
http://www.icourse163.org/course/BIT-268001
<class 'dict'>
<class 'bs4.element.Tag'>
Basic Python
3. Beautiful Soup元素的遍历
分为下行遍历、上行遍历以及平行遍历。
- 下行遍历
| 属性 | 说明 | 数据类型 |
|---|---|---|
| .contents | 子节点的列表，将<tag>所有子节点存入列表 | 列表 |
| .children | 子节点的迭代类型，与.contents类似，用于循环遍历子节点 | 迭代类型 |
| .descendants | 子孙节点的跌点类型，包含所有子孙节点，用于遍历循环 | 迭代类型 |
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
print(vSoup.head)
print(vSoup.head.contents)
<head><title>This is a python demo page</title></head>
[<title>This is a python demo page</title>]
print(vSoup.body.contents)
['\n', <p class="title"><b>The demo python introduces several python courses.</b></p>, '\n', <p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>, '\n']
len(vSoup.body.contents)
5
vSoup.body.contents[1]
<p class="title"><b>The demo python introduces several python courses.</b></p>
vSoup.body.contents[2]
'\n'
vSoup.body.contents[3]
<p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>
标签树的下行遍历代码：
### 遍历子节点
for vChild in vSoup.body.children:
print(vChild)
### 遍历子孙节点
for vChild in vSoup.body.children:
print(vChild)
- 上行遍历
| 属性 | 说明 |
|---|---|
| .parent | 节点的父亲标签 |
| .parents | 节点的先辈标签 |
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
vSoup.title.parent # tltle的父标签是head
<head><title>This is a python demo page</title></head>
vSoup.html.parent # html的父标签是自身
<html><head><title>This is a python demo page</title></head>
<body>
<p class="title"><b>The demo python introduces several python courses.</b></p>
<p class="course">Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:
<a class="py1" href="http://www.icourse163.org/course/BIT-268001" id="link1">Basic Python</a> and <a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>.</p>
</body></html>
vSoup.parent # vSoup是特殊对象，其父标签为空
### 查看上行标签的名字
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
for parent in vSoup.a.parents:
if parent is None:
print(parent)
else:
print(parent.name)
p
body
html
[document]
- 平行遍历
| 属性 | 说明 | 数据类型 |
|---|---|---|
| .next_sibling | 返回按照html文本顺序的下一个平行节点标签 | list |
| .previous_sibling | 返回按照html文本顺序的上一个平行节点的标签 | list |
| .next_siblings | 迭代类型，返回按照html文本顺序的后续所有平行节点标签 | 迭代类型 |
| .previous_siblings | 迭代类型，返回按照html文本顺序的前序所有平行节点标签 | 迭代类型 |
平行遍历必须发生在同一个父节点下。
import requests
from bs4 import BeautifulSoup
vUrl = requests.get("http://python123.io/ws/demo.html")
vDemo = vUrl.text
vSoup = BeautifulSoup(vDemo, "html.parser")
vSoup.a.next_sibling # 忘后一个平行节点是一个字符串
' and '
vSoup.a.next_sibling.next_sibling #往后两个平行节点也是一个a标签
<a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>
vSoup.a.previous_sibling # 前一个平行节点是一段文字
'Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses:\r\n'
vSoup.a.previous_sibling.previous_sibling # 前一个的前一个不存在，所以没有输出
标签数的平行遍历：
for vSibling in vSoup.a.next_siblings:
print(vSibling)
and
<a class="py2" href="http://www.icourse163.org/course/BIT-1001870001" id="link2">Advanced Python</a>
.
for vSibling in vSoup.a.previous_siblings:
print(vSibling)
Python is a wonderful general-purpose programming language. You can learn Python from novice to professional by tracking the following courses: