
老师 第一的运行结果为啥是空值,而第二个就能运行出来

from lxml import etree
import requests
url="https://book.douban.com/tag/%E5%B0%8F%E8%AF%B4"
headers={ 'Host':'book.douban.com',
'Upgrade-Insecure-Requests':'1',
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36'
}
req = requests.get(url=url,headers=headers)
content = req.text
content_dict=etree.HTML(content) #格式化
title_list = content_dict.xpath(r'div[2]/h2/a/@title')
for title in title_list:
print(title)
from lxml import etree
import requests
url="https://book.douban.com/tag/%E5%B0%8F%E8%AF%B4"
headers={ 'Host':'book.douban.com',
'Upgrade-Insecure-Requests':'1',
'User-Agent':'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/64.0.3282.140 Safari/537.36'
}
req = requests.get(url=url,headers=headers)
content = req.text
content_dict=etree.HTML(content) #格式化
title_list = content_dict.xpath(r'div[2]/h2/a/@title')
content_dict_allli = content_dict.xpath(r'//*[@id="subject_list"]/ul/li') #拿到列表
info_all = ''
for li in content_dict_allli:
# 书名/标题
title_list = li.xpath(r'div[2]/h2/a/@title') #取标签里的内容,注意地址是相对地址,不能直接拿来用 (注:和bs4不一样)
title =title_list[0]
title=title.replace(" ",'')
print(title)