1.简介
XPath是一门在XML和HTML文档中查找信息的语言,可以用来在XML和HTML文档中对元素和属性进行遍历
XPath的安装
Chrome插件XPath Helper
点Chrome浏览器右上角:更多工具-----扩展程序-----谷歌商店--------勾选XPath Helper(需要翻墙)
2.语法详解
#1.选取节点
'''
/ 如果是在最前面,代表从根节点选取,否则选择某节点下的某个节点.只查询子一辈的节点
/html 查询到一个结果
/div 查询到0个结果,因为根节点以下只有一个html子节点
/html/body 查询到1个结果
// 查询所有子孙节点
//head/script
//div
. 选取当前节点
.. 选取当前节点的父节点
@ 选取属性
//div[@id] 选择所有带有id属性的div元素
<div id="sidebar" class="sidebar" data-lg-tj-track-code="index_navigation" data-lg-tj-track-type="1">
'''
#2.谓语
'''
谓语是用来查找某个特定的节点或者包含某个指定的值的节点,被嵌在方括号中。
//body/div[1] body下的第一个div元素
//body/div[last()] body下的最后一个div元素
//body/div[position()<3] body下的位置小于3的元素
//div[@id] div下带id属性的元素
<div id="sidebar" class="sidebar" data-lg-tj-track-code="index_navigation" data-lg-tj-track-type="1">
//input[@id="serverTime"] input下id="serverTime"的元素
模糊匹配
//div[contains(@class,'f1')] div的class属性带有f1的
通配符 *
//body/* body下面所有的元素
//div[@*] 只要有用属性的div元素
//div[@id='footer'] //div 带有id='footer'属性的div下的所有div元素
//div[@class='job_bt'] //dd[@class='job-advantage']
运算符
//div[@class='job_detail'] and @id='job_tent'
//book/title | //book/price 选取 book 元素的所有 title 和 price 元素。
也可以百度搜索XPath语法
.//a/text() 当前标签下所有a标签的文字内容
//tr[position()>1 and position()<11] 位置大于1小于11
'''
#需要注意的知识点
'''
1./和//的区别:/代表子节点,//代表子孙节点,//用的比较多
2.contains有时候某个属性中包含了多个值,那么使用contains函数
//div[contains(@class,'lg')]
3.谓语中的下标是从1开始的,不是从0开始的
'''
3.要在python中使用xpath,要导入一个库 lxml。
这个是C编写的库,直接pip3 install lxml可能会有一些显示问题,但是不影响使用。
然而程序员特有的代码洁癖让我看见波浪线也不会爽,所以去https://www.lfd.uci.edu/~gohlke/pythonlibs/下载lxml的whl文件进行pip(根据自己的pycharm版本选择)
4.lxml和xpath的结合使用
# -*-coding:utf8 -*-
from lxml import etree
#1.获取所有tr标签
#2.获取第2个tr标签
#3.获取所有class等于even的标签
#4.获取所有a标签的href属性
#5.获取所有的职位信息(纯文本)
parser=etree.HTMLParser(encoding='utf-8')
html=etree.parse('tencent.html',parser=parser)
#1.获取所有tr标签
#xpath函数返回的是一个列表
# trs=html.xpath('//tr')
# print(trs)
# for tr in trs:
# print(etree.tostring(tr,encoding='utf-8').decode('utf-8'))
#2.获取第2个tr标签
# trs=html.xpath('//tr[2]')[0]
#这样直接找第2个tr标签,实际上会把所有的table下的第二个tr标签找出来,
#为了更精准,可以先把table标签找到,再找这个table下的第二个tr标签
# trs=html.xpath('//table[@class="tablelist"]//tr[1]')[0]
# print(etree.tostring(trs,encoding='utf-8').decode('utf-8'))
#3.获取所有class等于even的标签
# trs=html.xpath("//tr[@class='even']")
# for tr in trs:
# print(etree.tostring(tr, encoding='utf-8').decode('utf-8'))
#4.获取所有a标签的href属性
# a_list=html.xpath('//a/@href')
# for a in a_list:
# print(a)
#5.获取所有的职位信息(纯文本)
trs=html.xpath('//tr[position()>1 and position()<11]')
positions=[]
for tr in trs:
#写了//后,则一定会从整个文档找a标签,会无视前面的tr
# href=tr.xpath('//a')
#写了.后,则获取当前标签下的a标签
href=tr.xpath('.//a/@href')[0]
fullurl='http://hr.tencent.com/'+href
#title文本信息不是td[1]的直接子元素标签,所以要加./td[1]//text()
title=tr.xpath('./td[1]//text()')[0]
category=tr.xpath('./td[2]/text()')[0]
nums=tr.xpath('./td[3]/text()')[0]
address=tr.xpath('./td[4]/text()')[0]
pubtime=tr.xpath('./td[5]/text()')[0]
position={
'url':fullurl,
'title':title,
'category':category,
'nums':nums,
'pubtime':pubtime
}
positions.append(position)
# print(positions)
#6.获取纯文本信息还可以用string
# print(html.xpath("string(//tr[1])"))
# trs=html.xpath('//tr')
# for tr in trs:
# print(tr.xpath("string(.)").strip()
5.实战案例,豆瓣电影爬虫
# -*-coding:utf8 -*-
#1.将目标网站上的页面抓取下来
#2.将抓取下来的数据根据一定的规则进行提取
import requests
from lxml import etree
#1.将目标网站上的页面抓取下来
headers={
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36',
'Referer':'https://www.douban.com/',
}
url='https://movie.douban.com/'
response=requests.get(url,headers=headers)
text=response.text
html=etree.HTML(text)
ul=html.xpath("//ul[@class='ui-slide-content']")[0]
# print(etree.tostring(ul,encoding='utf-8').decode('utf-8'))
lis=ul.xpath('./li[@data-title]')
movies=[]
for li in lis:
title=li.xpath('@data-title')[0]
score=li.xpath('@data-rate')[0]
duration=li.xpath('@data-duration')[0]
region=li.xpath('@data-region')[0]
director=li.xpath('@data-director')[0]
actors=li.xpath('@data-actors')[0]
thumbnail=li.xpath('.//img/@src')[0]
movie={
'title':title,
'score':score,
'duration':duration,
'region':region,
'director':director,
'actors':actors,
'thumbnail':thumbnail
}
movies.append(movie)
print(movies)
6.实战案例,电影天堂爬虫
# -*-coding:utf8 -*-
import requests
from lxml import etree
# url='https://www.dytt8.net/html/gndy/dyzz/list_23_1.html'
headers = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36'
}
# response=requests.get(url,headers=headers)
# 在电影天堂的网页中,因为编码方式,requests库猜错了,所以response.text出现乱码
# print(response.text)
# text=response.content.decode('gbk')
BaseDomain = 'https://www.dytt8.net'
def get_detail_url(url):
response = requests.get(url, headers=headers)
# print(response.encoding)
# 默认解码方式ISO-8859-1
# text=response.content.decode('gbk')
# 在使用gbk解码时遇到了一些问题,第五页里有特殊字符,无法解析
# 估计是因为xpath默认解码方式和gbk不一致导致的,这时可以直接传requests.text
# 因为要获取的是英文字符,不指定解码方式也能得到
html = etree.HTML(response.text)
detail_urls = html.xpath('//table[@class="tbspan"]//a/@href')
detail_urls = list(map(lambda url: BaseDomain + url, detail_urls))
return detail_urls
def parse_detail_page(url):
response = requests.get(url, headers=headers)
text = response.content.decode('gbk')
html = etree.HTML(text)
title = html.xpath("//font[@color='#07519a' and position()=1]/text()")
zoomE = html.xpath("//div[@id='Zoom']")[0]
imgs = zoomE.xpath(".//img/@src")
cover = imgs[0]
screenshot = imgs[1]
infos = zoomE.xpath(".//text()")
movie = {
'title': title,
'cover': cover,
'screenshot': screenshot
}
def parse_info(info, rule):
return info.replace(rule, '').strip()
for index, info in enumerate(infos):
if info.startswith('◎年 代'):
info = parse_info(info, '◎年 代')
movie['year'] = info
elif info.startswith('◎产 地'):
info = parse_info(info, '◎产 地')
movie['country'] = info
elif info.startswith('◎类 别'):
info = parse_info(info, '◎类 别')
movie['category'] = info
elif info.startswith('◎豆瓣评分'):
info = parse_info(info, '◎豆瓣评分')
movie['douban_rating'] = info
elif info.startswith('◎片 长'):
info = parse_info(info, '◎片 长')
movie['duration'] = info
elif info.startswith('◎导 演'):
info = parse_info(info, '◎导 演')
movie['director'] = info
elif info.startswith('◎主 演'):
info = parse_info(info, '◎主 演')
actors = []
actors.append(info)
for x in range(index + 1, len(infos)):
actor = infos[x].strip()
if actor.startswith('◎简 介'):
break
actors.append(actor)
movie['actors'] = actors
elif info.startswith('◎简 介 '):
info=''
for x in range(index+1,len(infos)):
if infos[x].startswith('【下载地址】'):
break
info = info + infos[x].strip()
movie['profile']=info
download_url = html.xpath("//td[@bgcolor='#fdfddf']//a/@href")[0]
movie['download_url']=download_url
return movie
def spider():
# url = ['https://www.dytt8.net/html/gndy/dyzz/list_23_%s.html' % i for i in range(1, 8)]
base_url = 'https://www.dytt8.net/html/gndy/dyzz/list_23_{}.html'
movies=[]
for x in range(1, 8):
url = base_url.format(x)
detail_urls = get_detail_url(url)
for detail_url in detail_urls:
movie = parse_detail_page(detail_url)
movies.append(movie)
print(movies)
if __name__ == '__main__':
spider()
7.实战案例,腾讯招聘爬虫
# -*-coding:utf8 -*-
import requests
from lxml import etree
base_url = 'https://hr.tencent.com/position.php?tid=87&start={}0#a'
base_domain = 'https://hr.tencent.com/'
headers = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.119 Safari/537.36'
}
positions=[]
def parse_url(url):
detail_urls=[]
response=requests.get(url,headers=headers)
html=etree.HTML(response.text)
trs=html.xpath("//table[@class='tablelist']//tr[position()>1 and position()<12]")
for tr in trs:
href=tr.xpath('.//a/@href')[0]
url=base_domain+href
detail_urls.append(url)
return detail_urls
def parse_detail_page(url):
response=requests.get(url,headers=headers)
html=etree.HTML(response.text)
zoomE=html.xpath('//table[@class="tablelist textl"]')[0]
title=zoomE.xpath('.//tr[1]/td/text()')[0]
city=zoomE.xpath('.//tr[2]/td[1]/text()')[0]
category=zoomE.xpath('.//tr[2]/td[2]/text()')[0]
nums=zoomE.xpath('.//tr[2]/td[3]/text()')[0]
duty=zoomE.xpath('.//tr[3]//ul//text()')
dutys=''
for i in duty:
dutys=dutys+i.strip()
require=zoomE.xpath('.//tr[4]//ul//text()')
requires=''
for i in require:
requires=requires+i.strip()
position={
'title':title,
'city':city,
'category':category,
'nums':nums,
'dutys':dutys,
'requires':requires
}
return position
if __name__ == '__main__':
for i in range(1,10):
url=base_url.format(i)
detail_urls=parse_url(url)
for detail_url in detail_urls:
position=parse_detail_page(detail_url)
positions.append(position)
print(position)