Python爬虫利器二之Beautiful Soup的用法【转过来，乱了，从原网址看】

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# [Python爬虫利器二之Beautiful Soup的用法][Python_Beautiful Soup] #

http://cuiqingcai.com/1319.html

[Python][] [崔庆才][Link 1] 1年前 (2015-03-10)  97560℃ [41评论][41]

上一节我们介绍了正则表达式，它的内容其实还是蛮多的，如果一个正则匹配稍有差池，那可能程序就处在永久的循环之中，而且有的小伙伴们也对写正则表达式的写法用得不熟练，没关系，我们还有一个更强大的工具，叫Beautiful Soup，有了它我们可以很方便地提取出HTML或XML标签中的内容，实在是方便，这一节就让我们一起来感受一下Beautiful Soup的强大吧。

## 1. Beautiful Soup的简介 ##

简单来说，Beautiful Soup是python的一个库，最主要的功能是从网页抓取数据。官方解释如下：

> Beautiful Soup提供一些简单的、python式的函数用来处理导航、搜索、修改分析树等功能。它是一个工具箱，通过解析文档为用户提供需要抓取的数据，因为简单，所以不需要多少代码就可以写出一个完整的应用程序。
> 
> Beautiful Soup自动将输入文档转换为Unicode编码，输出文档转换为utf-8编码。你不需要考虑编码方式，除非文档没有指定一个编码方式，这时，Beautiful Soup就不能自动识别编码方式了。然后，你仅仅需要说明一下原始编码方式就可以了。
> 
> Beautiful Soup已成为和lxml、html6lib一样出色的python解释器，为用户灵活地提供不同的解析策略或强劲的速度。

废话不多说，我们来试一下吧~

## 2. Beautiful Soup 安装 ##

Beautiful Soup 3 目前已经停止开发，推荐在现在的项目中使用Beautiful Soup 4，不过它已经被移植到BS4了，也就是说导入时我们需要 import bs4 。所以这里我们用的版本是 Beautiful Soup 4.3.2 (简称BS4)，另外据说 BS4 对 Python3 的支持不够好，不过我用的是 Python2.7.7，如果有小伙伴用的是 Python3 版本，可以考虑下载 BS3 版本。

可以利用 pip 或者 easy\_install 来安装，以下两种方法均可

easy\_install beautifulsoup4

pip install beautifulsoup4

如果想安装最新的版本，请直接下载安装包来手动安装，也是十分方便的方法。在这里我安装的是 Beautiful Soup 4.3.2

[Beautiful Soup 3.2.1][][Beautiful Soup 4.3.2][]

下载完成之后解压

运行下面的命令即可完成安装

sudo python setup.py install

然后需要安装 lxml

easy\_install lxml

pip install lxml

另一个可供选择的解析器是纯Python实现的 html5lib , html5lib的解析方式与浏览器相同,可以选择下列方法来安装html5lib:

easy\_install html5lib

pip install html5lib

Beautiful Soup支持Python标准库中的HTML解析器,还支持一些第三方的解析器，如果我们不安装它，则 Python 会使用 Python默认的解析器，lxml 解析器更加强大，速度更快，推荐安装。

<thead”>

<table> 
 <tbody> 
  <tr> 
   <th>解析器</th> 
   <th>使用方法</th> 
   <th>优势</th> 
   <th>劣势</th> 
  </tr> 
 </tbody> 
 <tbody> 
  <tr> 
   <td>Python标准库</td> 
   <td>BeautifulSoup(markup, “html.parser”)</td> 
   <td> 
    <ul> 
     <li>Python的内置标准库</li> 
     <li>执行速度适中</li> 
     <li>文档容错能力强</li> 
    </ul> </td> 
   <td> 
    <ul> 
     <li>Python 2.7.3 or 3.2.2)前 的版本中文档容错能力差</li> 
    </ul> </td> 
  </tr> 
  <tr> 
   <td>lxml HTML 解析器</td> 
   <td>BeautifulSoup(markup, “lxml”)</td> 
   <td> 
    <ul> 
     <li>速度快</li> 
     <li>文档容错能力强</li> 
    </ul> </td> 
   <td> 
    <ul> 
     <li>需要安装C语言库</li> 
    </ul> </td> 
  </tr> 
  <tr> 
   <td>lxml XML 解析器</td> 
   <td>BeautifulSoup(markup, [“lxml”, “xml”])BeautifulSoup(markup, “xml”)</td> 
   <td> 
    <ul> 
     <li>速度快</li> 
     <li>唯一支持XML的解析器</li> 
    </ul> </td> 
   <td> 
    <ul> 
     <li>需要安装C语言库</li> 
    </ul> </td> 
  </tr> 
  <tr> 
   <td>html5lib</td> 
   <td>BeautifulSoup(markup, “html5lib”)</td> 
   <td> 
    <ul> 
     <li>最好的容错性</li> 
     <li>以浏览器的方式解析文档</li> 
     <li>生成HTML5格式的文档</li> 
    </ul> </td> 
   <td> 
    <ul> 
     <li>速度慢</li> 
     <li>不依赖外部扩展</li> 
    </ul> </td> 
  </tr> 
 </tbody> 
</table>

## 3. 开启Beautiful Soup 之旅 ##

在这里先分享官方文档链接，不过内容是有些多，也不够条理，在此本文章做一下整理方便大家参考。

[官方文档][Link 2]

## 4. 创建 Beautiful Soup 对象 ##

首先必须要导入 bs4 库

from bs4 import BeautifulSoup

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>from</span> 
      <span>bs4 </span> 
      <span>import </span> 
      <span>BeautifulSoup</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

我们创建一个字符串，后面的例子我们便会用它来演示

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"></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 beautifulsoup 对象

soup = BeautifulSoup(html)

另外，我们还可以用本地 HTML 文件来创建对象，例如

soup = BeautifulSoup(open('index.html'))

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span></span> 
      <span>=</span> 
      <span> </span> 
      <span>BeautifulSoup</span> 
      <span>(</span> 
      <span>open</span> 
      <span>(</span> 
      <span>'index.html'</span> 
      <span>)</span> 
      <span>)</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

上面这句代码便是将本地 index.html 文件打开，用它来创建 soup 对象

下面我们来打印一下 soup 对象的内容，格式化输出

print soup.prettify()

以上便是输出结果，格式化打印出了它的内容，这个函数经常用到，小伙伴们要记好咯。

## 5. 四大对象种类 ##

Beautiful Soup将复杂HTML文档转换成一个复杂的树形结构,每个节点都是Python对象,所有对象可以归纳为4种:

*  Tag
 *  NavigableString
 *  BeautifulSoup
 *  Comment

下面我们进行一一介绍

### **（1）Tag** ###

Tag 是什么？通俗点讲就是 HTML 中的一个个标签，例如

<title>The Dormouse's story</title>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>title</span> 
      <span>&gt;</span> 
      <span>The</span> 
      <span>Dormouse</span>' 
      <span>s</span> 
      <span></span> 
      <span>story</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>title</span> 
      <span>&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>a</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"sister"</span> 
      <span></span> 
      <span>href</span> 
      <span>=</span> 
      <span>"http://example.com/elsie"</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>"link1"</span> 
      <span>&gt;</span> 
      <span>Elsie</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>a</span> 
      <span>&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

上面的 title a 等等 HTML 标签加上里面包括的内容就是 Tag，下面我们来感受一下怎样用 Beautiful Soup 来方便地获取 Tags

下面每一段代码中注释部分即为运行结果

print soup.title \#<title>The Dormouse's story</title>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>title</span> 
     </div> 
     <div> 
      <span>#&lt;title&gt;The Dormouse's story&lt;/title&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.head \#<head><title>The Dormouse's story</title></head>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
     </div> 
     <div> 
      <span>#&lt;head&gt;&lt;title&gt;The Dormouse's story&lt;/title&gt;&lt;/head&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.a \#<a class="sister" href="http://example.com/elsie" id="link1"></a>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
     </div> 
     <div> 
      <span>#&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.p \#<p class="title" name="dromouse"><b>The Dormouse's story</b></p>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
     </div> 
     <div> 
      <span>#&lt;p class="title" name="dromouse"&gt;&lt;b&gt;The Dormouse's story&lt;/b&gt;&lt;/p&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

我们可以利用 soup加标签名轻松地获取这些标签的内容，是不是感觉比正则表达式方便多了？不过有一点是，它查找的是在所有内容中的第一个符合要求的标签，如果要查询所有的标签，我们在后面进行介绍。

我们可以验证一下这些对象的类型

print type(soup.a) \#<class 'bs4.element.Tag'>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>type</span> 
      <span>(</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#&lt;class 'bs4.element.Tag'&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

对于 Tag，它有两个重要的属性，是 name 和 attrs，下面我们分别来感受一下

**name**

print soup.name print soup.head.name \#\[document\] \#head

soup 对象本身比较特殊，它的 name 即为 \[document\]，对于其他内部标签，输出的值便为标签本身的名称。

**attrs**

print soup.p.attrs \#\{'class': \['title'\], 'name': 'dromouse'\}

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>attrs</span> 
     </div> 
     <div> 
      <span>#{'class': ['title'], 'name': 'dromouse'}</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

在这里，我们把 p 标签的所有属性打印输出了出来，得到的类型是一个字典。

如果我们想要单独获取某个属性，可以这样，例如我们获取它的 class 叫什么

print soup.p\['class'\] \#\['title'\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>[</span> 
      <span>'class'</span> 
      <span>]</span> 
     </div> 
     <div> 
      <span>#['title']</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

还可以这样，利用get方法，传入属性的名称，二者是等价的

print soup.p.get('class') \#\['title'\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>get</span> 
      <span>(</span> 
      <span>'class'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#['title']</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

我们可以对这些属性和内容等等进行修改，例如

soup.p\['class'\]="newClass" print soup.p \#<p class="newClass" name="dromouse"><b>The Dormouse's story</b></p>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>[</span> 
      <span>'class'</span> 
      <span>]</span> 
      <span>=</span> 
      <span>"newClass"</span> 
     </div> 
     <div> 
      <span>print </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
     </div> 
     <div> 
      <span>#&lt;p class="newClass" name="dromouse"&gt;&lt;b&gt;The Dormouse's story&lt;/b&gt;&lt;/p&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

还可以对这个属性进行删除，例如

del soup.p\['class'\] print soup.p \#<p name="dromouse"><b>The Dormouse's story</b></p>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>del</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>[</span> 
      <span>'class'</span> 
      <span>]</span> 
     </div> 
     <div> 
      <span>print </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
     </div> 
     <div> 
      <span>#&lt;p name="dromouse"&gt;&lt;b&gt;The Dormouse's story&lt;/b&gt;&lt;/p&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

不过，对于修改删除的操作，不是我们的主要用途，在此不做详细介绍了，如果有需要，请查看前面提供的官方文档

### **（2）NavigableString** ###

既然我们已经得到了标签的内容，那么问题来了，我们要想获取标签内部的文字怎么办呢？很简单，用 .string 即可，例如

print soup.p.string \#The Dormouse's story

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
     <div> 
      <span>#The Dormouse's story</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

这样我们就轻松获取到了标签里面的内容，想想如果用正则表达式要多麻烦。它的类型是一个 NavigableString，翻译过来叫 可以遍历的字符串，不过我们最好还是称它英文名字吧。

来检查一下它的类型

print type(soup.p.string) \#<class 'bs4.element.NavigableString'>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>type</span> 
      <span>(</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>string</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#&lt;class 'bs4.element.NavigableString'&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（3）BeautifulSoup** ###

BeautifulSoup 对象表示的是一个文档的全部内容.大部分时候,可以把它当作Tag 对象，是一个特殊的 Tag，我们可以分别获取它的类型，名称，以及属性来感受一下

print type(soup.name) \#<type 'unicode'> print soup.name \# \[document\] print soup.attrs \#\{\} 空字典

### **（4）Comment** ###

Comment 对象是一个特殊类型的 NavigableString 对象，其实输出的内容仍然不包括注释符号，但是如果不好好处理它，可能会对我们的文本处理造成意想不到的麻烦。

我们找一个带注释的标签

print soup.a print soup.a.string print type(soup.a.string)

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
     </div> 
     <div> 
      <span>print </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
     <div> 
      <span>print</span> 
      <span>type</span> 
      <span>(</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
      <span>.</span> 
      <span>string</span> 
      <span>)</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

运行结果如下

<a class="sister" href="http://example.com/elsie" id="link1"></a> Elsie <class 'bs4.element.Comment'>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>a</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"sister"</span> 
      <span></span> 
      <span>href</span> 
      <span>=</span> 
      <span>"http://example.com/elsie"</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>"link1"</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>!</span> 
      <span>--</span> 
      <span></span> 
      <span>Elsie</span> 
      <span> </span> 
      <span>--</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>a</span> 
      <span>&gt;</span> 
     </div> 
     <div> 
      <span></span> 
      <span>Elsie</span> 
      <span></span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>class</span> 
      <span></span> 
      <span>'bs4.element.Comment'</span> 
      <span>&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

a 标签里的内容实际上是注释，但是如果我们利用 .string 来输出它的内容，我们发现它已经把注释符号去掉了，所以这可能会给我们带来不必要的麻烦。

另外我们打印输出下它的类型，发现它是一个 Comment 类型，所以，我们在使用前最好做一下判断，判断代码如下

if type(soup.a.string)==bs4.element.Comment: print soup.a.string

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>if</span> 
      <span></span> 
      <span>type</span> 
      <span>(</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
      <span>.</span> 
      <span>string</span> 
      <span>)</span> 
      <span>==</span> 
      <span>bs4</span> 
      <span>.</span> 
      <span>element</span> 
      <span>.</span> 
      <span>Comment</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>a</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

上面的代码中，我们首先判断了它的类型，是否为 Comment 类型，然后再进行其他操作，如打印输出。

## 6. 遍历文档树 ##

### **（1）直接子节点** ###

> **要点：.contents .children 属性**

**.contents**

tag 的 .content 属性可以将tag的子节点以列表的方式输出

print soup.head.contents \#\[<title>The Dormouse's story</title>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>contents</span>&nbsp; 
     </div> 
     <div> 
      <span>#[&lt;title&gt;The Dormouse's story&lt;/title&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

输出方式为列表，我们可以用列表索引来获取它的某一个元素

print soup.head.contents\[0\] \#<title>The Dormouse's story</title>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>contents</span> 
      <span>[</span> 
      <span>0</span> 
      <span>]</span> 
     </div> 
     <div> 
      <span>#&lt;title&gt;The Dormouse's story&lt;/title&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**.children**

它返回的不是一个 list，不过我们可以通过遍历获取所有子节点。

我们打印输出 .children 看一下，可以发现它是一个 list 生成器对象

print soup.head.children \#<listiterator object at 0x7f71457f5710>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>children</span> 
     </div> 
     <div> 
      <span>#&lt;listiterator object at 0x7f71457f5710&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

我们怎样获得里面的内容呢？很简单，遍历一下就好了，代码及结果如下

for child in soup.body.children: print child

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>for</span> 
      <span></span> 
      <span>child</span> 
      <span> </span> 
      <span>in</span> 
      <span>&nbsp;&nbsp;</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>body</span> 
      <span>.</span> 
      <span>children</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print </span> 
      <span>child</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

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

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
     <div style="height:15px">
       4 
     </div> 
     <div style="height:15px">
       5 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>p</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"title"</span> 
      <span></span> 
      <span>name</span> 
      <span>=</span> 
      <span>"dromouse"</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>b</span> 
      <span>&gt;</span> 
      <span>The</span> 
      <span>Dormouse</span>' 
      <span>s</span> 
      <span></span> 
      <span>story</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>b</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>p</span> 
      <span>&gt;</span> 
     </div> 
     <div>
       &nbsp; 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>p</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"story"</span> 
      <span>&gt;</span> 
      <span>Once</span> 
      <span>upon</span> 
      <span> </span> 
      <span>a</span> 
      <span></span> 
      <span>time </span> 
      <span>there </span> 
      <span>were</span> 
      <span>three </span> 
      <span>little </span> 
      <span>sisters</span> 
      <span>;</span> 
      <span></span> 
      <span>and</span> 
      <span> </span> 
      <span>their</span> 
      <span>names </span> 
      <span>were</span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>a</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"sister"</span> 
      <span></span> 
      <span>href</span> 
      <span>=</span> 
      <span>"http://example.com/elsie"</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>"link1"</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>!</span> 
      <span>--</span> 
      <span></span> 
      <span>Elsie</span> 
      <span> </span> 
      <span>--</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>a</span> 
      <span>&gt;</span> 
      <span>,</span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>a</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"sister"</span> 
      <span></span> 
      <span>href</span> 
      <span>=</span> 
      <span>"http://example.com/lacie"</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>"link2"</span> 
      <span>&gt;</span> 
      <span>Lacie</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>a</span> 
      <span>&gt;</span> 
      <span></span> 
      <span>and</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

###  **（2）所有子孙节点** ###

> **知识点：.descendants 属性**

**.descendants**

.contents 和 .children 属性仅包含tag的直接子节点，.descendants 属性可以对所有tag的子孙节点进行递归循环，和 children类似，我们也需要遍历获取其中的内容。

for child in soup.descendants: print child

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>for</span> 
      <span></span> 
      <span>child</span> 
      <span> </span> 
      <span>in</span> 
      <span></span> 
      <span>soup</span> 
      <span>.</span> 
      <span>descendants</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print </span> 
      <span>child</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

运行结果如下，可以发现，所有的节点都被打印出来了，先生最外层的 HTML标签，其次从 head 标签一个个剥离，以此类推。

<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 class="sister" href="http://example.com/elsie" id="link1"></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>; and they lived at the bottom of a well.</p> <p class="story">...</p> </body></html> <head><title>The Dormouse's story</title></head> <title>The Dormouse's story</title> The Dormouse's story <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 class="sister" href="http://example.com/elsie" id="link1"></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>; and they lived at the bottom of a well.</p> <p class="story">...</p> </body> <p class="title" name="dromouse"><b>The Dormouse's story</b></p> <b>The Dormouse's story</b> The Dormouse's story <p class="story">Once upon a time there were three little sisters; and their names were <a class="sister" href="http://example.com/elsie" id="link1"></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>; and they lived at the bottom of a well.</p> Once upon a time there were three little sisters; and their names were <a class="sister" href="http://example.com/elsie" id="link1"></a> Elsie , <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> Lacie and <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a> Tillie ; and they lived at the bottom of a well. <p class="story">...</p> ...

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
     <div style="height:15px">
       4 
     </div> 
     <div style="height:15px">
       5 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>html</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>head</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>title</span> 
      <span>&gt;</span> 
      <span>The</span> 
      <span>Dormouse</span> 
      <span>'s story&lt;/title&gt;&lt;/head&gt;</span> 
     </div> 
     <div> 
      <span>&lt;body&gt;</span> 
     </div> 
     <div> 
      <span>&lt;p class="title" name="dromouse"&gt;&lt;b&gt;The Dormouse'</span> 
      <span>s</span> 
      <span></span> 
      <span>story</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>b</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>p</span> 
      <span>&gt;</span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>p</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"story"</span> 
      <span>&gt;</span> 
      <span>Once</span> 
      <span>upon</span> 
      <span> </span> 
      <span>a</span> 
      <span></span> 
      <span>time </span> 
      <span>there </span> 
      <span>were</span> 
      <span>three </span> 
      <span>little </span> 
      <span>sisters</span> 
      <span>;</span> 
      <span></span> 
      <span>and</span> 
      <span> </span> 
      <span>their</span> 
      <span>names </span> 
      <span>were</span> 
     </div> 
     <div> 
      <span>&lt;</span> 
      <span>a</span> 
      <span></span> 
      <span>class</span> 
      <span>=</span> 
      <span>"sister"</span> 
      <span></span> 
      <span>href</span> 
      <span>=</span> 
      <span>"http://example.com/elsie"</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>"link1"</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>!</span> 
      <span>--</span> 
      <span></span> 
      <span>Elsie</span> 
      <span> </span> 
      <span>--</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>a</span> 
      <span>&gt;</span> 
      <span>,</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

###  **（3）节点内容** ###

> 知识点：.string 属性

如果tag只有一个 NavigableString 类型子节点,那么这个tag可以使用.string 得到子节点。如果一个tag仅有一个子节点,那么这个tag也可以使用.string 方法,输出结果与当前唯一子节点的.string 结果相同。

通俗点说就是：如果一个标签里面没有标签了，那么 .string 就会返回标签里面的内容。如果标签里面只有唯一的一个标签了，那么 .string 也会返回最里面的内容。例如

print soup.head.string \#The Dormouse's story print soup.title.string \#The Dormouse's story

如果tag包含了多个子节点,tag就无法确定，string 方法应该调用哪个子节点的内容, .string 的输出结果是 None

print soup.html.string \# None

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>html</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
     <div> 
      <span># None</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（4）多个内容** ###

> **知识点： .strings .stripped\_strings 属性**

**.strings**

获取多个内容，不过需要遍历获取，比如下面的例子

for string in soup.strings: print(repr(string)) \# u"The Dormouse's story" \# u'\\n\\n' \# u"The Dormouse's story" \# u'\\n\\n' \# u'Once upon a time there were three little sisters; and their names were\\n' \# u'Elsie' \# u',\\n' \# u'Lacie' \# u' and\\n' \# u'Tillie' \# u';\\nand they lived at the bottom of a well.' \# u'\\n\\n' \# u'...' \# u'\\n'

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
     <div style="height:15px">
       4 
     </div> 
     <div style="height:15px">
       5 
     </div> 
     <div style="height:15px">
       6 
     </div> 
     <div style="height:15px">
       7 
     </div> 
     <div style="height:15px">
       8 
     </div> 
     <div style="height:15px">
       9 
     </div> 
     <div style="height:15px">
       10 
     </div> 
     <div style="height:15px">
       11 
     </div> 
     <div style="height:15px">
       12 
     </div> 
     <div style="height:15px">
       13 
     </div> 
     <div style="height:15px">
       14 
     </div> 
     <div style="height:15px">
       15 
     </div> 
     <div style="height:15px">
       16 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>for</span> 
      <span></span> 
      <span>string</span> 
      <span> </span> 
      <span>in</span> 
      <span></span> 
      <span>soup</span> 
      <span>.</span> 
      <span>strings</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print</span> 
      <span>(</span> 
      <span>repr</span> 
      <span>(</span> 
      <span>string</span> 
      <span>)</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u"The Dormouse's story"</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'\n\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u"The Dormouse's story"</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'\n\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Once upon a time there were three little sisters; and their names were\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Elsie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u',\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Lacie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u' and\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Tillie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u';\nand they lived at the bottom of a well.'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'\n\n'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'...'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'\n'</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**.stripped\_strings**

输出的字符串中可能包含了很多空格或空行,使用 .stripped\_strings 可以去除多余空白内容

for string in soup.stripped\_strings: print(repr(string)) \# u"The Dormouse's story" \# u"The Dormouse's story" \# u'Once upon a time there were three little sisters; and their names were' \# u'Elsie' \# u',' \# u'Lacie' \# u'and' \# u'Tillie' \# u';\\nand they lived at the bottom of a well.' \# u'...'

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
     <div style="height:15px">
       4 
     </div> 
     <div style="height:15px">
       5 
     </div> 
     <div style="height:15px">
       6 
     </div> 
     <div style="height:15px">
       7 
     </div> 
     <div style="height:15px">
       8 
     </div> 
     <div style="height:15px">
       9 
     </div> 
     <div style="height:15px">
       10 
     </div> 
     <div style="height:15px">
       11 
     </div> 
     <div style="height:15px">
       12 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>for</span> 
      <span></span> 
      <span>string</span> 
      <span> </span> 
      <span>in</span> 
      <span></span> 
      <span>soup</span> 
      <span>.</span> 
      <span>stripped_strings</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print</span> 
      <span>(</span> 
      <span>repr</span> 
      <span>(</span> 
      <span>string</span> 
      <span>)</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u"The Dormouse's story"</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u"The Dormouse's story"</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Once upon a time there were three little sisters; and their names were'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Elsie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u','</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Lacie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'and'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'Tillie'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u';\nand they lived at the bottom of a well.'</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span># u'...'</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（5）父节点** ###

>  **知识点： .parent 属性**

p = soup.p print p.parent.name \#body

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>p</span> 
      <span></span> 
      <span>=</span> 
      <span> </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
     </div> 
     <div> 
      <span>print</span> 
      <span> </span> 
      <span>p</span> 
      <span>.</span> 
      <span>parent</span> 
      <span>.</span> 
      <span>name</span> 
     </div> 
     <div> 
      <span>#body</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

content = soup.head.title.string print content.parent.name \#title

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>content</span> 
      <span></span> 
      <span>=</span> 
      <span> </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>title</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
     <div> 
      <span>print </span> 
      <span>content</span> 
      <span>.</span> 
      <span>parent</span> 
      <span>.</span> 
      <span>name</span> 
     </div> 
     <div> 
      <span>#title</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（6）全部父节点** ###

> **知识点：.parents 属性**

通过元素的 .parents 属性可以递归得到元素的所有父辈节点，例如

content = soup.head.title.string for parent in content.parents: print parent.name

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>content</span> 
      <span></span> 
      <span>=</span> 
      <span> </span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>title</span> 
      <span>.</span> 
      <span>string</span> 
     </div> 
     <div> 
      <span>for</span> 
      <span> </span> 
      <span>parent</span> 
      <span></span> 
      <span>in</span> 
      <span>&nbsp;&nbsp;</span> 
      <span>content</span> 
      <span>.</span> 
      <span>parents</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>print</span> 
      <span>parent</span> 
      <span>.</span> 
      <span>name</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

title head html \[document\]

###  **（7）兄弟节点** ###

> **知识点：.next\_sibling .previous\_sibling 属性**

兄弟节点可以理解为和本节点处在统一级的节点，.next\_sibling 属性获取了该节点的下一个兄弟节点，.previous\_sibling 则与之相反，如果节点不存在，则返回 None

注意：实际文档中的tag的 .next\_sibling 和 .previous\_sibling 属性通常是字符串或空白，因为空白或者换行也可以被视作一个节点，所以得到的结果可能是空白或者换行

print soup.p.next\_sibling \# 实际该处为空白 print soup.p.prev\_sibling \#None 没有前一个兄弟节点，返回 None print soup.p.next\_sibling.next\_sibling \#<p class="story">Once upon a time there were three little sisters; and their names were \#<a class="sister" href="http://example.com/elsie" id="link1"></a>, \#<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> and \#<a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>; \#and they lived at the bottom of a well.</p> \#下一个节点的下一个兄弟节点是我们可以看到的节点

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
     <div style="height:15px">
       4 
     </div> 
     <div style="height:15px">
       5 
     </div> 
     <div style="height:15px">
       6 
     </div> 
     <div style="height:15px">
       7 
     </div> 
     <div style="height:15px">
       8 
     </div> 
     <div style="height:15px">
       9 
     </div> 
     <div style="height:15px">
       10 
     </div> 
     <div style="height:15px">
       11 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>next_sibling</span> 
     </div> 
     <div> 
      <span>#&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 实际该处为空白</span> 
     </div> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>prev_sibling</span> 
     </div> 
     <div> 
      <span>#None&nbsp;&nbsp; 没有前一个兄弟节点，返回 None</span> 
     </div> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>p</span> 
      <span>.</span> 
      <span>next_sibling</span> 
      <span>.</span> 
      <span>next_sibling</span> 
     </div> 
     <div> 
      <span>#&lt;p class="story"&gt;Once upon a time there were three little sisters; and their names were</span> 
     </div> 
     <div> 
      <span>#&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;,</span> 
     </div> 
     <div> 
      <span>#&lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt; and</span> 
     </div> 
     <div> 
      <span>#&lt;a class="sister" href="http://example.com/tillie" id="link3"&gt;Tillie&lt;/a&gt;;</span> 
     </div> 
     <div> 
      <span>#and they lived at the bottom of a well.&lt;/p&gt;</span> 
     </div> 
     <div> 
      <span>#下一个节点的下一个兄弟节点是我们可以看到的节点</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（8）全部兄弟节点** ###

> **知识点：.next\_siblings .previous\_siblings 属性**

通过 .next\_siblings 和.previous\_siblings 属性可以对当前节点的兄弟节点迭代输出

for sibling in soup.a.next\_siblings: print(repr(sibling)) \# u',\\n' \# <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a> \# u' and\\n' \# <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a> \# u'; and they lived at the bottom of a well.' \# None

### **（9）前后节点** ###

> **知识点：.next\_element .previous\_element 属性**

与 .next\_sibling .previous\_sibling 不同，它并不是针对于兄弟节点，而是在所有节点，不分层次

比如 head 节点为

<head><title>The Dormouse's story</title></head>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>&lt;</span> 
      <span>head</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>title</span> 
      <span>&gt;</span> 
      <span>The</span> 
      <span>Dormouse</span>' 
      <span>s</span> 
      <span></span> 
      <span>story</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>title</span> 
      <span>&gt;</span> 
      <span>&lt;</span> 
      <span>/</span> 
      <span>head</span> 
      <span>&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

那么它的下一个节点便是 title，它是不分层次关系的

print soup.head.next\_element \#<title>The Dormouse's story</title>

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>head</span> 
      <span>.</span> 
      <span>next_element</span> 
     </div> 
     <div> 
      <span>#&lt;title&gt;The Dormouse's story&lt;/title&gt;</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### **（10）所有前后节点** ###

> **知识点：.next\_elements .previous\_elements 属性**

通过 .next\_elements 和.previous\_elements 的迭代器就可以向前或向后访问文档的解析内容,就好像文档正在被解析一样

for element in last\_a\_tag.next\_elements: print(repr(element)) \# u'Tillie' \# u';\\nand they lived at the bottom of a well.' \# u'\\n\\n' \# <p class="story">...</p> \# u'...' \# u'\\n' \# None

以上是遍历文档树的基本用法。

## 7.搜索文档树 ##

### （1）find\_all( name , attrs , recursive , text , \*\*kwargs ) ###

find\_all() 方法搜索当前tag的所有tag子节点,并判断是否符合过滤器的条件

**1）name 参数**

name 参数可以查找所有名字为 name 的tag,字符串对象会被自动忽略掉

**A.传字符串**

最简单的过滤器是字符串.在搜索方法中传入一个字符串参数,Beautiful Soup会查找与字符串完整匹配的内容,下面的例子用于查找文档中所有的<b>标签

soup.find\_all('b') \# \[<b>The Dormouse's story</b>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>'b'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;b&gt;The Dormouse's story&lt;/b&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.find\_all('a') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:45px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>'a'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;, &lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;, &lt;a class="sister" href="http://example.com/tillie" id="link3"&gt;Tillie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**B.传正则表达式**

如果传入正则表达式作为参数,Beautiful Soup会通过正则表达式的 match() 来匹配内容.下面例子中找出所有以b开头的标签,这表示<body>和<b>标签都应该被找到

import re for tag in soup.find\_all(re.compile("^b")): print(tag.name) \# body \# b

**C.传列表**

如果传入列表参数,Beautiful Soup会将与列表中任一元素匹配的内容返回.下面代码找到文档中所有<a>标签和<b>标签

soup.find\_all(\["a", "b"\]) \# \[<b>The Dormouse's story</b>, \# <a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>, \# <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, \# <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>\]

**D.传 True**

True 可以匹配任何值,下面代码查找到所有的tag,但是不会返回字符串节点

for tag in soup.find\_all(True): print(tag.name) \# html \# head \# title \# body \# p \# b \# p \# a \# a

**E.传方法**

如果没有合适过滤器,那么还可以定义一个方法,方法只接受一个元素参数 [ \[4\]][_4] ,如果这个方法返回 True 表示当前元素匹配并且被找到,如果不是则反回False

下面方法校验了当前元素,如果包含 class 属性却不包含id 属性,那么将返回 True:

def has\_class\_but\_no\_id(tag): return tag.has\_attr('class') and not tag.has\_attr('id')

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>def</span> 
      <span>has_class_but_no_id</span> 
      <span>(</span> 
      <span>tag</span> 
      <span>)</span> 
      <span>:</span> 
     </div> 
     <div> 
      <span>&nbsp;&nbsp;&nbsp;&nbsp;</span> 
      <span>return</span> 
      <span></span> 
      <span>tag</span> 
      <span>.</span> 
      <span>has_attr</span> 
      <span>(</span> 
      <span>'class'</span> 
      <span>)</span> 
      <span></span> 
      <span>and</span> 
      <span> </span> 
      <span>not</span> 
      <span></span> 
      <span>tag</span> 
      <span>.</span> 
      <span>has_attr</span> 
      <span>(</span> 
      <span>'id'</span> 
      <span>)</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

将这个方法作为参数传入 find\_all() 方法,将得到所有<p>标签:

soup.find\_all(has\_class\_but\_no\_id) \# \[<p class="title"><b>The Dormouse's story</b></p>, \# <p class="story">Once upon a time there were...</p>, \# <p class="story">...</p>\]

**2）keyword 参数**

> **注意：如果一个指定名字的参数不是搜索内置的参数名,搜索时会把该参数当作指定名字tag的属性来搜索,如果包含一个名字为 id 的参数,Beautiful Soup会搜索每个tag的”id”属性**

soup.find\_all(id='link2') \# \[<a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>id</span> 
      <span>=</span> 
      <span>'link2'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

如果传入 href 参数,Beautiful Soup会搜索每个tag的”href”属性

soup.find\_all(href=re.compile("elsie")) \# \[<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>href</span> 
      <span>=</span> 
      <span>re</span> 
      <span>.</span> 
      <span>compile</span> 
      <span>(</span> 
      <span>"elsie"</span> 
      <span>)</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;Elsie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

使用多个指定名字的参数可以同时过滤tag的多个属性

soup.find\_all(href=re.compile("elsie"), id='link1') \# \[<a class="sister" href="http://example.com/elsie" id="link1">three</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>href</span> 
      <span>=</span> 
      <span>re</span> 
      <span>.</span> 
      <span>compile</span> 
      <span>(</span> 
      <span>"elsie"</span> 
      <span>)</span> 
      <span>,</span> 
      <span></span> 
      <span>id</span> 
      <span>=</span> 
      <span>'link1'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;three&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

在这里我们想用 class 过滤，不过 class 是 python 的关键词，这怎么办？加个下划线就可以

soup.find\_all("a", class\_="sister") \# \[<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>, \# <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, \# <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>\]

有些tag属性在搜索不能使用,比如HTML5中的 data-\* 属性

data\_soup = BeautifulSoup('<div data-foo="value">foo!</div>') data\_soup.find\_all(data-foo="value") \# SyntaxError: keyword can't be an expression

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>data_soup</span> 
      <span></span> 
      <span>=</span> 
      <span> </span> 
      <span>BeautifulSoup</span> 
      <span>(</span> 
      <span>'&lt;div data-foo="value"&gt;foo!&lt;/div&gt;'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>data_soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>data</span> 
      <span>-</span> 
      <span>foo</span> 
      <span>=</span> 
      <span>"value"</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># SyntaxError: keyword can't be an expression</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

但是可以通过 find\_all() 方法的attrs 参数定义一个字典参数来搜索包含特殊属性的tag

data\_soup.find\_all(attrs=\{"data-foo": "value"\}) \# \[<div data-foo="value">foo!</div>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>data_soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>attrs</span> 
      <span>=</span> 
      <span>{ </span> 
      <span>"data-foo"</span> 
      <span>:</span> 
      <span></span> 
      <span>"value"</span> 
      <span>}</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;div data-foo="value"&gt;foo!&lt;/div&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**3）text 参数**

通过 text 参数可以搜搜文档中的字符串内容.与name 参数的可选值一样, text 参数接受 字符串 , 正则表达式 , 列表, True

soup.find\_all(text="Elsie") \# \[u'Elsie'\] soup.find\_all(text=\["Tillie", "Elsie", "Lacie"\]) \# \[u'Elsie', u'Lacie', u'Tillie'\] soup.find\_all(text=re.compile("Dormouse")) \[u"The Dormouse's story", u"The Dormouse's story"\]

**4）limit 参数**

find\_all() 方法返回全部的搜索结构,如果文档树很大那么搜索会很慢.如果我们不需要全部结果,可以使用limit 参数限制返回结果的数量.效果与SQL中的limit关键字类似,当搜索到的结果数量达到limit 的限制时,就停止搜索返回结果.

文档树中有3个tag符合搜索条件,但结果只返回了2个,因为我们限制了返回数量

soup.find\_all("a", limit=2) \# \[<a class="sister" href="http://example.com/elsie" id="link1">Elsie</a>, \# <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
     <div style="height:15px">
       3 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>soup</span> 
      <span>.</span> 
      <span>find_all</span> 
      <span>(</span> 
      <span>"a"</span> 
      <span>,</span> 
      <span></span> 
      <span>limit</span> 
      <span>=</span> 
      <span>2</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span># [&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;Elsie&lt;/a&gt;,</span> 
     </div> 
     <div> 
      <span>#&nbsp;&nbsp;&lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

**5）recursive 参数**

调用tag的 find\_all() 方法时,Beautiful Soup会检索当前tag的所有子孙节点,如果只想搜索tag的直接子节点,可以使用参数recursive=False .

一段简单的文档:

<html> <head> <title> The Dormouse's story </title> </head> ...

是否使用 recursive 参数的搜索结果:

soup.html.find\_all("title") \# \[<title>The Dormouse's story</title>\] soup.html.find\_all("title", recursive=False) \# \[\]

### （2）find( name , attrs , recursive , text , \*\*kwargs ) ###

它与 find\_all() 方法唯一的区别是 find\_all() 方法的返回结果是值包含一个元素的列表,而find() 方法直接返回结果

### （3）find\_parents() find\_parent() ###

find\_all() 和 find() 只搜索当前节点的所有子节点,孙子节点等. find\_parents() 和 find\_parent() 用来搜索当前节点的父辈节点,搜索方法与普通tag的搜索方法相同,搜索文档搜索文档包含的内容

### （4）find\_next\_siblings() find\_next\_sibling() ###

这2个方法通过 .next\_siblings 属性对当 tag 的所有后面解析的兄弟 tag 节点进行迭代, find\_next\_siblings() 方法返回所有符合条件的后面的兄弟节点,find\_next\_sibling() 只返回符合条件的后面的第一个tag节点

### （5）find\_previous\_siblings() find\_previous\_sibling() ###

这2个方法通过 .previous\_siblings 属性对当前 tag 的前面解析的兄弟 tag 节点进行迭代, find\_previous\_siblings() 方法返回所有符合条件的前面的兄弟节点, find\_previous\_sibling() 方法返回第一个符合条件的前面的兄弟节点

### （6）find\_all\_next() find\_next() ###

这2个方法通过 .next\_elements 属性对当前 tag 的之后的 tag 和字符串进行迭代, find\_all\_next() 方法返回所有符合条件的节点, find\_next() 方法返回第一个符合条件的节点

### （7）find\_all\_previous() 和 find\_previous() ###

这2个方法通过 .previous\_elements 属性对当前节点前面的 tag 和字符串进行迭代, find\_all\_previous() 方法返回所有符合条件的节点, find\_previous()方法返回第一个符合条件的节点

> **注：以上（2）（3）（4）（5）（6）（7）方法参数用法与 find\_all() 完全相同，原理均类似，在此不再赘述。**

## 8.CSS选择器 ##

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') \#\[<title>The Dormouse's story</title>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'title'</span> 
      <span>)</span>&nbsp; 
     </div> 
     <div> 
      <span>#[&lt;title&gt;The Dormouse's story&lt;/title&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

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

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:45px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'a'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;, &lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;, &lt;a class="sister" href="http://example.com/tillie" id="link3"&gt;Tillie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.select('b') \#\[<b>The Dormouse's story</b>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'b'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;b&gt;The Dormouse's story&lt;/b&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### （2）通过类名查找 ###

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

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:45px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'.sister'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;, &lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;, &lt;a class="sister" href="http://example.com/tillie" id="link3"&gt;Tillie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### （3）通过 id 名查找 ###

print soup.select('\#link1') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'#link1'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### （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') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'p #link1'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

直接子标签查找

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

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>"head &gt; title"</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;title&gt;The Dormouse's story&lt;/title&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

### （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('a\[class="sister"\]') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>, <a class="sister" href="http://example.com/lacie" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" id="link3">Tillie</a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:45px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'a[class="sister"]'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;, &lt;a class="sister" href="http://example.com/lacie" id="link2"&gt;Lacie&lt;/a&gt;, &lt;a class="sister" href="http://example.com/tillie" id="link3"&gt;Tillie&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

print soup.select('a\[href="http://example.com/elsie"\]') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'a[href="http://example.com/elsie"]'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

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\[href="http://example.com/elsie"\]') \#\[<a class="sister" href="http://example.com/elsie" id="link1"></a>\]

<table style=""> 
 <tbody> 
  <tr> 
   <td> 
    <div style="font-size:12px!important; line-height:15px!important"> 
     <div style="height:15px">
       1 
     </div> 
     <div style="height:15px">
       2 
     </div> 
    </div> </td> 
   <td> 
    <div style=""> 
     <div> 
      <span>print</span> 
      <span>soup</span> 
      <span>.</span> 
      <span>select</span> 
      <span>(</span> 
      <span>'p a[href="http://example.com/elsie"]'</span> 
      <span>)</span> 
     </div> 
     <div> 
      <span>#[&lt;a class="sister" href="http://example.com/elsie" id="link1"&gt;&lt;!-- Elsie --&gt;&lt;/a&gt;]</span> 
     </div> 
    </div> </td> 
  </tr> 
 </tbody> 
</table>

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。

soup = BeautifulSoup(html, 'lxml') print type(soup.select('title')) print soup.select('title')\[0\].get\_text() for title in soup.select('title'): print title.get\_text()

好，这就是另一种与 find\_all 方法有异曲同工之妙的查找方法，是不是感觉很方便？

## 总结 ##

本篇内容比较多，把 Beautiful Soup 的方法进行了大部分整理和总结，不过这还不算完全，仍然有 Beautiful Soup 的修改删除功能，不过这些功能用得比较少，只整理了查找提取的方法，希望对大家有帮助！小伙伴们加油！

熟练掌握了 Beautiful Soup，一定会给你带来太多方便，加油吧！

转载请注明：[静觅][Link 3] » [ Python爬虫利器二之Beautiful Soup的用法][Python_Beautiful Soup]

[Python_Beautiful Soup]: http://cuiqingcai.com/1319.html
[Python]: http://cuiqingcai.com/category/technique/python
[Link 1]: http://cuiqingcai.com/author/cqcre
[41]: http://cuiqingcai.com/1319.html#comments
[Beautiful Soup 3.2.1]: https://pypi.python.org/pypi/BeautifulSoup/3.2.1
[Beautiful Soup 4.3.2]: https://pypi.python.org/pypi/beautifulsoup4/4.3.2
[Link 2]: http://beautifulsoup.readthedocs.org/zh_CN/latest
[_4]: http://www.crummy.com/software/BeautifulSoup/bs4/doc/index.zh.html#id85
[Link 3]: http://cuiqingcai.com