python爬虫-数据解析（xpath）

xpath基本概念

xpath解析：最常用且最便捷高效的一种解析方式。通用性强。

xpath解析原理

• 1.实例化一个etree的对象，且需要将被解析的页面源码数据加载到该对象中
• 2.调用etree对象中的xpath方法结合xpath表达式实现标签的定位和内容的捕获。

环境安装

pip install lxml

如何实例化一个etree对象：

from lxml import etree

• 1.将本地的html文件中的远吗数据加载到etree对象中：

etree.parse(filePath)

• 2.可以将从互联网上获取的原码数据加载到该对象中：

etree.HTML(‘page_text’)

xpath(‘xpath表达式’)

- /:表示的是从根节点开始定位。表示一个层级
- //:表示多个层级。可以表示从任意位置开始定位
- 属性定位：//div[@class='song'] tag[@attrName='attrValue']
- 索引定位：//div[@class='song']/p[3] 索引从1开始的
- 取文本：
	- /text()获取的是标签中直系的文本内容
	- //text()标签中非直系的文本内容（所有文本内容）
- 取属性：
	/@attrName	==>img/src

xpath爬取58二手房实例

爬取网址

https://xa.58.com/ershoufang/

完整代码

from lxml import etree
import requests

if __name__ == '__main__':
    headers = {
     
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36'
    }
    url = 'https://xa.58.com/ershoufang/'
    page_text = requests.get(url=url,headers=headers).text
    tree = etree.HTML(page_text)
    div_list = tree.xpath('//section[@class="list"]/div')
    fp = open('./58同城二手房.txt','w',encoding='utf-8')
    for div in div_list:
        title = div.xpath('.//div[@class="property-content-title"]/h3/text()')[0]
        print(title)
        fp.write(title+'\n'+'\n')

效果图

xpath图片解析下载实例

爬取网址

https://pic.netbian.com/4kmeinv/

完整代码

import requests,os
from lxml import etree

if __name__ == '__main__':
    headers = {
     
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36'
    }
    url = 'https://pic.netbian.com/4kmeinv/'
    page_text = requests.get(url=url,headers=headers).text
    tree = etree.HTML(page_text)
    li_list = tree.xpath('//div[@class="slist"]/ul/li/a')
    if not os.path.exists('./piclibs'):
        os.mkdir('./piclibs')
    for li in li_list:
        detail_url ='https://pic.netbian.com' + li.xpath('./img/@src')[0]
        detail_name = li.xpath('./img/@alt')[0]+'.jpg'
        detail_name = detail_name.encode('iso-8859-1').decode('GBK')
        detail_path = './piclibs/' + detail_name
        detail_data = requests.get(url=detail_url, headers=headers).content
        with open(detail_path,'wb') as fp:
            fp.write(detail_data)
            print(detail_name,'seccess!!')

效果图

xpath爬取全国城市名称实例

爬取网址

https://www.aqistudy.cn/historydata/

完整代码

import requests
from lxml import etree

if __name__ == '__main__':
    url = 'https://www.aqistudy.cn/historydata/'
    headers = {
     
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36',
    }
    page_text = requests.get(url=url,headers=headers).content.decode('utf-8')
    tree = etree.HTML(page_text)
    #热门城市   //div[@class="bottom"]/ul/li
    #全部城市   //div[@class="bottom"]/ul/div[2]/li
    a_list = tree.xpath('//div[@class="bottom"]/ul/li | //div[@class="bottom"]/ul/div[2]/li')
    fp = open('./citys.txt','w',encoding='utf-8')
    i = 0
    for a in a_list:
        city_name = a.xpath('.//a/text()')[0]
        fp.write(city_name+'\t')
        i=i+1
        if i == 6:
            i = 0
            fp.write('\n')
    print('爬取成功')

效果图

xpath爬取简历模板实例

爬取网址

https://sc.chinaz.com/jianli/free.html

完整代码

import requests,os
from lxml import etree

if __name__ == '__main__':
    url = 'https://sc.chinaz.com/jianli/free.html'
    headers = {
     
        'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.141 Safari/537.36',
    }
    page_text = requests.get(url=url,headers=headers).content.decode('utf-8')
    tree = etree.HTML(page_text)
    a_list = tree.xpath('//div[@class="box col3 ws_block"]/a')
    if not os.path.exists('./简历模板'):
        os.mkdir('./简历模板')
    for a in a_list:
        detail_url = 'https:'+a.xpath('./@href')[0]
        detail_page_text = requests.get(url=detail_url,headers=headers).content.decode('utf-8')
        detail_tree = etree.HTML(detail_page_text)
        detail_a_list = detail_tree.xpath('//div[@class="clearfix mt20 downlist"]/ul/li[1]/a')
        for a in detail_a_list:
            download_name = detail_tree.xpath('//div[@class="ppt_tit clearfix"]/h1/text()')[0]
            download_url = a.xpath('./@href')[0]
            download_data = requests.get(url=download_url,headers=headers).content
            download_path = './简历模板/'+download_name+'.rar'
            with open(download_path,'wb') as fp:
                fp.write(download_data)
                print(download_name,'success!!')

效果图