python爬虫之xpath的基本使用详解

脚本专栏 2025/1/11 佚名

3 2 1

一、简介

XPath 是一门在 XML 文档中查找信息的语言。XPath 可用来在 XML 文档中对元素和属性进行遍历。XPath 是 W3C XSLT 标准的主要元素，并且 XQuery 和 XPointer 都构建于 XPath 表达之上。

二、安装

pip3 install lxml

三、使用

1、导入

from lxml import etree

2、基本使用

from lxml import etree
wb_data = """
    <div>
      <ul>
         <li class="item-0"><a href="link1.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >first item</a></li>

         <li class="item-1"><a href="link2.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >second item</a></li>

         <li class="item-inactive"><a href="link3.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >third item</a></li>

         <li class="item-1"><a href="link4.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fourth item</a></li>

         <li class="item-0"><a href="link5.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fifth item</a>
       </ul>
     </div>

    """
html = etree.HTML(wb_data)
print(html)
result = etree.tostring(html)
print(result.decode("utf-8"))

从下面的结果来看，我们打印机html其实就是一个python对象，etree.tostring(html)则是不全里html的基本写法，补全了缺胳膊少腿的标签。

 <Element html at 0x39e58f0>
<html><body><div>
      <ul>
         <li class="item-0"><a href="link1.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >first item</a></li>

         <li class="item-1"><a href="link2.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >second item</a></li>

         <li class="item-inactive"><a href="link3.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >third item</a></li>

         <li class="item-1"><a href="link4.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fourth item</a></li>

         <li class="item-0"><a href="link5.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fifth item</a>

       </li></ul>
     </div>
    </body></html>

3、获取某个标签的内容(基本使用)，注意，获取a标签的所有内容，a后面就不用再加正斜杠，否则报错。

写法一

html = etree.HTML(wb_data)

html_data = html.xpath('/html/body/div/ul/li/a')

print(html)

for i in html_data:

  print(i.text)

<Element html at 0x12fe4b8>

first item

second item

third item

fourth item

fifth item

写法二（直接在需要查找内容的标签后面加一个/text()就行）

html = etree.HTML(wb_data)

html_data = html.xpath('/html/body/div/ul/li/a/text()')

print(html)

for i in html_data:

  print(i) 

<Element html at 0x138e4b8>

first item

second item

third item

fourth item

fifth item

4、打开读取html文件

#使用parse打开html的文件

html = etree.parse('test.html')

html_data = html.xpath('//*')<br>#打印是一个列表，需要遍历

print(html_data)

for i in html_data:

  print(i.text)

html = etree.parse('test.html')

html_data = etree.tostring(html,pretty_print=True)

res = html_data.decode('utf-8')

print(res)

 

打印：

<div>

   <ul>

     <li class="item-0"><a href="link1.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >first item</a></li>

     <li class="item-1"><a href="link2.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" >second item</a></li>

     <li class="item-inactive"><a href="link3.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >third item</a></li>

     <li class="item-1"><a href="link4.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fourth item</a></li>

     <li class="item-0"><a href="link5.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" >fifth item</a></li>

   </ul>

</div>

5、打印指定路径下a标签的属性（可以通过遍历拿到某个属性的值，查找标签的内容）

html = etree.HTML(wb_data)

html_data = html.xpath('/html/body/div/ul/li/a/@href')

for i in html_data:

  print(i)

打印：

link1.html

link2.html

link3.html

link4.html

link5.html

6、我们知道我们使用xpath拿到得都是一个个的ElementTree对象，所以如果需要查找内容的话，还需要遍历拿到数据的列表。

查到绝对路径下a标签属性等于link2.html的内容。

html = etree.HTML(wb_data)

html_data = html.xpath('/html/body/div/ul/li/a[@href="link2.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]/text()')

print(html_data)

for i in html_data:

  print(i)

打印：

['second item']

second item

7、上面我们找到全部都是绝对路径（每一个都是从根开始查找），下面我们查找相对路径，例如，查找所有li标签下的a标签内容。

html = etree.HTML(wb_data)

html_data = html.xpath('//li/a/text()')

print(html_data)

for i in html_data:

  print(i)

打印：

['first item', 'second item', 'third item', 'fourth item', 'fifth item']

first item

second item

third item

fourth item

fifth item

8、上面我们使用绝对路径，查找了所有a标签的属性等于href属性值，利用的是/---绝对路径，下面我们使用相对路径，查找一下l相对路径下li标签下的a标签下的href属性的值，注意，a标签后面需要双//。

html = etree.HTML(wb_data)

html_data = html.xpath('//li/a//@href')

print(html_data)

for i in html_data:

  print(i)

打印：

['link1.html', 'link2.html', 'link3.html', 'link4.html', 'link5.html']

link1.html

link2.html

link3.html

link4.html

link5.html

9、相对路径下跟绝对路径下查特定属性的方法类似，也可以说相同。

html = etree.HTML(wb_data)

html_data = html.xpath('//li/a[@href="link2.html" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]')

print(html_data)

for i in html_data:

  print(i.text)

打印：

[<Element a at 0x216e468>]

second item

10、查找最后一个li标签里的a标签的href属性

html = etree.HTML(wb_data)

html_data = html.xpath('//li[last()]/a/text()')

print(html_data)

for i in html_data:

  print(i)

打印：

['fifth item']

fifth item

11、查找倒数第二个li标签里的a标签的href属性

html = etree.HTML(wb_data)

html_data = html.xpath('//li[last()-1]/a/text()')

print(html_data)

for i in html_data:

  print(i)

打印：

['fourth item']

fourth item

12、如果在提取某个页面的某个标签的xpath路径的话，可以如下图：

//*[@id="kw"]

解释：使用相对路径查找所有的标签，属性id等于kw的标签。

常用

#!/usr/bin/env python
# -*- coding:utf-8 -*-
from scrapy.selector import Selector, HtmlXPathSelector
from scrapy.http import HtmlResponse
html = """<!DOCTYPE html>
<html>
  <head lang="en">
    <meta charset="UTF-8">
    <title></title>
  </head>
  <body>
    <ul>
      <li class="item-"><a id='i1' href="link.html" rel="external nofollow" rel="external nofollow" >first item</a></li>
      <li class="item-0"><a id='i2' href="llink.html" rel="external nofollow" >first item</a></li>
      <li class="item-1"><a href="llink2.html" rel="external nofollow" rel="external nofollow" >second item<span>vv</span></a></li>
    </ul>
    <div><a href="llink2.html" rel="external nofollow" rel="external nofollow" >second item</a></div>
  </body>
</html>
"""
response = HtmlResponse(url='http://example.com', body=html,encoding='utf-8')
# hxs = HtmlXPathSelector(response)
# print(hxs)
# hxs = Selector(response=response).xpath('//a')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[2]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[@href="link.html" rel="external nofollow" rel="external nofollow" ][@id="i1"]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[contains(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[starts-with(@href, "link")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]')
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/text()').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//a[re:test(@id, "i\d+")]/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('/html/body/ul/li/a/@href').extract()
# print(hxs)
# hxs = Selector(response=response).xpath('//body/ul/li/a/@href').extract_first()
# print(hxs)
 
# ul_list = Selector(response=response).xpath('//body/ul/li')
# for item in ul_list:
#   v = item.xpath('./a/span')
#   # 或
#   # v = item.xpath('a/span')
#   # 或
#   # v = item.xpath('*/a/span')
#   print(v)

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。

python,xpath爬虫,python使用xpath

标签：

python,xpath爬虫,python使用xpath

免责声明：本站文章均来自网站采集或用户投稿，网站不提供任何软件下载或自行开发的软件！如有用户或公司发现本站内容信息存在侵权行为，请邮件告知！ 858582#qq.com

白云城资源网 Copyright www.dyhadc.com

评论“python爬虫之xpath的基本使用详解”

python爬虫之xpath的基本使用详解

暂无“python爬虫之xpath的基本使用详解”评论...

www.dyhadc.com 白云城资源网

129,905影音资源

244,626技术资源

111,817软件资源

578,645站长资源

python爬虫之xpath的基本使用详解

python,xpath爬虫,python使用xpath

使用python读取txt文件的内容,并删除重复的行数方法

python对excel文档去重及求和的实例

评论“python爬虫之xpath的基本使用详解”

RTX 5090要首发性能要翻倍！三星展示GDDR7显存

更新日志

友情链接

python爬虫之xpath的基本使用详解

python,xpath爬虫,python使用xpath

使用python读取txt文件的内容,并删除重复的行数方法

python对excel文档去重及求和的实例

评论“python爬虫之xpath的基本使用详解”

RTX 5090要首发 性能要翻倍！三星展示GDDR7显存

更新日志

友情链接

RTX 5090要首发性能要翻倍！三星展示GDDR7显存