Python爬虫如何使用CSS选择器-创新互联
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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
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 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"))
运行结果
[The Dormouse's story ] [The Dormouse's story] [, Lacie, Tillie]
(2)通过类名查找
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select(".title"))
运行结果
[The Dormouse's story
]
(3)通过id名查找
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("#link1"))
运行结果
[The Dormouse's story
]
(4)组合查找
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("p #link1"))
运行结果
[]
(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。
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("a[class='sister']"))
运行结果
[, Lacie, Tillie]
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。
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 创建 Beautiful Soup 对象,指定lxml解析器 soup = BeautifulSoup(html, "lxml") print(soup.select("p a[class='sister']"))
运行结果
[, Lacie, Tillie]
(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。
#!/usr/bin/python3 # -*- coding:utf-8 -*- from bs4 import BeautifulSoup html = """The Dormouse's story 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.
...
""" # 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())
运行结果
[, Lacie, Tillie] Lacie Tillie
注意:为注释内容,未输出
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