python爬虫之BeautifulSoup 使用select方法详解

2020-01-04 16:38:45

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本文介绍了python/95394.html">python爬虫之BeautifulSoup 使用select方法详解，分享给大家。具体如下：

<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" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1"><!-- Elsie --></a>,<a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> and<a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link3">Tillie</a>;and they lived at the bottom of a well.</p><p class="story">...</p>"""

我们在写 CSS 时，标签名不加任何修饰，类名前加点，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()，返回类型是 list

（1）通过标签名查找

print soup.select('title') #[<title>The Dormouse's story</title>] print soup.select('a')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>, <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>] print soup.select('b')#[<b>The Dormouse's story</b>]

（2）通过类名查找

print soup.select('.sister')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>, <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>]

（3）通过 id 名查找

print soup.select('#link1')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

（4）组合查找

组合查找即和写 class 文件时，标签名与类名、id名进行的组合原理是一样的，例如查找 p 标签中，id 等于 link1的内容，二者需要用空格分开

print soup.select('p #link1')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

直接子标签查找

print soup.select("head > title")#[<title>The Dormouse's story</title>]

（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。

print soup.select("head > title")#[<title>The Dormouse's story</title>] print soup.select('a[href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

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

print soup.select('p a[href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]')#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

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