Python爬虫之CSS选择器
CSS选择器
这是另一种与find_all()方法有异曲同工的查找方法,写CSS时,标签名不加任何修饰,类名前加.,id名前加#。
在这里我们也可以利用类似的方法来筛选元素,用到的方法是soup.select(),返回的类型是list。
(1)通过标签名查找
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("title")) print(soup.select("b")) print(soup.select("a"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<title>The Dormouse's story</title>] [<b>The Dormouse's story</b>] [<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>]</pre>(2)通过类名查找
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select(".title"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<p class="title" name="dromouse"><b>The Dormouse's story</b></p>]</pre>(3)通过id名查找
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("#link1"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<p class="title" name="dromouse"><b>The Dormouse's story</b></p>]</pre>相关推荐:《Python视频教程》
(4)组合查找
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("p #link1"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<a class="sister" href="http://example.com/elsie" id="link1"><!-- Elsie --></a>]</pre>(5)属性查找
查找时还可以加入属性元素,属性需要用中括号括起来,注意属性和标签属于同一节点,所以中间不能加空格,否则会无法匹配到。
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("a[class='sister']"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<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>]</pre>同样,属性仍然可以与上述查找方式组合,不在同一节点的空格隔开,同一节点的不加空格。
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("p a[class='sister']"))</pre>运行结果
<pre class="brush:php;toolbar:false">[<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>]</pre>(6)获取内容
以上的select()方法返回的结果都是列表形式,可以遍历形式输出,然后用get_text()方法来获取它的内容。
<pre class="brush:php;toolbar:false">#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """ <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> """ # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("p a[class='sister']")) for item in soup.select("p a[class='sister']"): print(item.get_text())</pre>运行结果
<pre class="brush:php;toolbar:false">[<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>] Lacie Tillie</pre>注意:<!-- Elsie -->为注释内容,未输出
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