python爬虫之BeautifulSoup4介绍
CSS 选择器：BeautifulSoup4
例子：
response = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1"><!-- Elsie --></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.</p>
<p class="story">...</p>
"""
四大对象种类
1. Tag
注：
soup = BeautifulSoup(response,"html.parser")
print(soup.p) #查找的是第一个符合要求的标签
2. NavigableString
3. BeautifulSoup
4. Comment
遍历文档树
1. 直接子节点 ：.contents .children 属性
2. 所有子孙节点: .descendants 属性
3. 节点内容: .string 属性
搜索文档树
1.find_all(name, attrs, recursive, text, **kwargs)
注：
print(soup.find_all("a')) #查找所有的<a>标签
print(soup.find_all(["a","b","p"])) #返回所有的<a>标签、<b>标签和<p>标签
print(soup.find_all(id="link1"))
print(soup.find_all(text="Elsie")) #返回文本等于Elsie的内容
2. CSS选择器
（1）通过标签名查找
print(soup.select('a'))
（2）通过类名查找
print(soup.select('.sister'))
[<a class="sister" href="http://example.com/elsie" id="link1"><!-- Elsie --></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>]
（3）通过 id 名查找
print(soup.select("#link1"))
#[<a class="sister" href="http://example.com/elsie" id="link1"><!-- Elsie --></a>]
（4）组合查找
print(soup.select('p #link1')) #p标签下ID等于link1的内容，之间空格分开
print(soup.select("head > title")) #直接子标签查找
（5）属性查找
print(soup.select('a[class="sister"])') #属性和标签属于同一节点，所以中间不能加空格
print(soup.select('p a[href="http://example.com/elsie"]'))
(6) 获取内容
print (soup.select('title')[0].get_text())
print(soup.select("title")[0].text)
============================================================================================
name = (film.select("[title]")[0].text) #肖申克的救赎
===========================================================================================
# -*- coding:utf-8 from bs4 import BeautifulSoup #BeautifulSoup对象四种类型tag|NavigableString|BeautifulSoap|Comment response = html = """ <html><head><title>The Dormouse's story</title></head> <body> <p class="title" name="dromouse" title="标题"><b>The Dormouse's story中文</b></p> <p class="story">Once upon a time there were three little sisters; and their names were <a href="http://example.com/elsie" class="sister" id="link1"><!-- Elsie --></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.</p> <p class="story">...</p> """ soup = BeautifulSoup(response,"html.parser") #tags;属性======查找的是第一个符合要求的标签 print("soup.a.attrs:",soup.a.attrs) print("soup.p:",soup.p) print('soup.p["class"]:',soup.p["class"]) print('soup.p.get("class"):',soup.p.get("class")) ##NavigableString print('soup.p.string:',soup.p.string) #获取标签中的文字内容 # BeautifulSoup #大部分时候,可以把它当作 Tag 对象,可以分别获取它的类型，名称 print(soup.attrs) # 文档本身的属性为空 #Comment # Comment 对象是一个特殊类型的 NavigableString 对象，其输出的内容不包括注释符号 print(soup.a) print(soup.a.string) #遍历文档树 print(soup.head.contents) #输出方式为列表 print(soup.head.children) #list生成器对象 获取所有子节点，可以通过遍历获取所有子节点 print("++++++++++++++++") for child in soup.body.children: print(child) print("===============") print(soup.select("[title]")[0].text) # print(soup.find_all(["a","b","p"])) print(soup.select('title')[0]) print(soup.select('title')[0].text) print(soup.select('title')[0].get_text())
