爬虫-lxml用法

pip install lxml

# coding=utf-8
from lxml import etree


text = ‘‘‘ <div> <ul> 
        <li class="item-1"><a>first item</a></li> 
        <li class="item-1"><a href="link2.html">second item</a></li> 
        <li class="item-inactive"><a href="link3.html">third item</a></li> 
        <li class="item-1"><a href="link4.html">fourth item</a></li> 
        <li class="item-0"><a href="link5.html">fifth item</a>  
        </ul> </div> ‘‘‘

html = etree.HTML(text)
print(html)
#查看element对象中包含的字符串
# print(etree.tostring(html).decode())

#获取class为item-1 li下的a的herf
ret1 = html.xpath("//li[@class=‘item-1‘]/a/@href")
print(ret1)

#获取class含有item-1 li下的a的文本  contains包含 
ret2 = html.xpath("//li[contains(@class,‘item-1‘)]/a/text()")
print(ret2)

#每个li是一条新闻，把url和文本组成字典
for href in ret1:
    item = {}
    item["href"] = href
    item["title"] = ret2[ret1.index(href)]
    print(item)

print("*"*100)
#分组，根据li标签进行分组，对每一组继续写xpath
ret3 = html.xpath("//li[@class=‘item-1‘]")
print(ret3)
for i in ret3:
    item=  {}
    item["title"] = i.xpath("a/text()")[0] if len(i.xpath("./a/text()"))>0 else None
    item["href"] = i.xpath("./a/@href")[0] if len( i.xpath("./a/@href"))>0 else None
    print(item)