lxml 介绍
- lxml 是一个 HTML/XML 的解析器，主要的功能是如何解析和提取 HTML/XML 数据
- lxml 和正则一样，用 C 语言实现的，是一款高性能的 Python HTML/XML 解析器，可以利用 XPath 语法，快速定位元素以及节点的信息
- lxml Python 官方文档：https://lxml.de/index.html
- 安装命令：
pip install lxml
基本使用
可以利用 lxml 解析 HTML 代码，并且在解析 HTML 代码的时候，如果 HTML 代码不规范，缺少标签，lxml 会帮我们自动的进行补全
# 使用lxml的etree库
from lxml import etree
text = """
<div>
<ul>
<li class="item-0"><a href="link1.html">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>
# 注意，此处缺少一个 </li> 闭合标签
</ul>
</div
"""
# 利用etree.HTML，将字符串解析为HTML文档
html = etree.HTML(text)
# 按字符串序列化HTML文档
result = etree.tostring(html)
print(result)
输出结果如下，可以看到 lxml 会自动修改 HTML 代码，不仅补全了 li 标签，还添加了 body,html 标签
<html>
<body>
<div>
<ul>
<li class="item-0"><a href="link1.html">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></li>
</ul>
</div>
</body>
</html>
从文件中读取 HTML 代码
除了直接使用字符串进行解析，lxml 还支持冲文件中读取内容，新建一个 hello.html 文件，内容如下，然后利用 etree.parse() 方法来读取文件
<div>
<ul>
<li class="item-0"><a href="link1.html">first item</a></li>
<li class="item-1"><a href="link2.html">second item</a></li>
<li class="item-inactive">
<a href="link3.html"><span class="bold">third item</span></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></li>
</ul>
</div>
from lxml import etree
# 读取HTML文件
html = etree.parse('hello.html')
result = etree.tostring(html, pretty_print=True)
# 输出结果和之前相同
print(result)
在lxml中使用XPath语法
- 获取所有li标签
from lxml import etree
html = etree.parse('hello.html')
print(type(html)) # 显示 etree.parse() 返回类型
result = html.xpath('//li')
print(result) # 打印 <li> 标签的元素集合
- 获取所有li元素下的所有class属性的值
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li/@class')
print(result)
- 获取所有li标签下href为link1.html的a标签
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li/a[@href="link1.html"]')
print(result)
- 获取li标签下所有span标签
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li//span')
# //li/span 是不对的，因为 / 是用来获取子元素的，span 并不是 li 的子元素，所有要用双斜杠
print(result)
- 获取li标签下的a标签里的所有class
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li/a//@class')
print(result)
- 获取最后一个li的a的href属性对应的值
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li[last()]/a/@href')
print(result)
- 获取倒数第二个li元素的内容
from lxml import etree
html = etree.parse('hello.html')
result = html.xpath('//li[last()-1]/a')
# result = html.xpath('//li[last()-1]/a/text()')
print(result)
案例：使用requests和xpath爬取电影天堂
from lxml import etree
import requests
BASE_DOMAIN = 'https://www.dytt8.net'
HEADERS = {
'User-Agent': 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36'
}
def get_detail_urls(url):
response = requests.get(url, headers=HEADERS)
text = response.text
html = etree.HTML(text)
detail_urls = html.xpath("//table[@class='tbspan']//a/@href")
detail_urls = map(lambda url: BASE_DOMAIN + url, detail_urls)
return detail_urls
def parse_detail_page(url):
movie = {}
response = requests.get(url, headers=HEADERS)
text = response.content.decode('gbk')
html = etree.HTML(text)
def parse_info(info, rule):
return info.replace(rule, "").strip()
title = html.xpath("//div[@class='title_all']//font[@color='#07519a']/text()")[0]
movie['title'] = title
zoomE = html.xpath("//div[@id='Zoom']")[0]
imgs = zoomE.xpath(".//img/@src")
cover = imgs[0]
screenshot = imgs[1]
movie['cover'] = cover
movie['screenshot'] = screenshot
infos = zoomE.xpath(".//text()")
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["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 = [info]
for x in range(index+1, len(infos)):
actor = infos[x].strip()
if actor.startswith('◎'):
break
actors.append(actor)
movie["actors"] = actors
elif info.startswith('◎简 介 '):
info = parse_info(info, '◎简 介')
for x in range(index+1, len(infos)):
profile = infos[x].strip()
movie["profile"] = profile
download_url = html.xpath("//td[@bgcolor='#fdfddf']/a/@href")[0]
movie["download_url"] = download_url
return movie
def spider():
base_url = 'https://www.dytt8.net/html/gndy/dyzz/list_23_{}.html'
for x in range(1, 3):
url = base_url.format(x)
detail_urls = get_detail_urls(url)
for detial_url in detail_urls:
movie = parse_detail_page(detial_url)
print(movie)
if __name__ == "__main__":
spider()