bs4模块

2022-05-09 22:32:45 作者：互联网

requests+bs4爬取汽车之家

import requests
# pip3 install beautifulsoup4
from bs4 import BeautifulSoup

res = requests.get('https://www.autohome.com.cn/news/1/#liststart')
# print(res.text)
# html.parser bs4默认的解析库
soup = BeautifulSoup(res.text, 'html.parser')
# 使用bs4的查找
ul_list = soup.find_all(name='ul', class_='article')
# print(len(ul_list))
for ul in ul_list:
    # 找ul标签下所有的li标签
    li_list = ul.find_all(name='li')
    for li in li_list:
        h3 = li.find(name='h3')
        if h3:
            title = h3.text  # 获取h3标签的文本内容
            desc = li.find(name='p').text
            img = li.find(name='img')['src']
            if not img.startswith('http'):
                img='https:'+img
            url = 'https:' + li.find('a')['href']
            print('''
            新闻标题：%s
            新闻摘要：%s
            新闻图片：%s
            新闻地址：%s
            ''' % (title, desc, img, url))
            # 把图片保存到本地
            res_img=requests.get(img)
            img_name=img.split('/')[-1]
            with open('./img/%s'%img_name,'wb') as f:
                for line in res_img.iter_content(1024):
                    f.write(line)

            # 把数据存到数据库 pymysql写入数据库--》建库建表--》cursor.exec(insert ..)-->commit

bs4遍历文档树

from bs4 import BeautifulSoup

html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" id="id_p">lqz<b>The Dormouse's story</b></p>

<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>

<p class="story">...</p>
"""
# html.parser 内置的，速度一般,容错能力强
# lxml    第三方，速度快,容错能力强
# soup=BeautifulSoup(html_doc,'html.parser')
# pip3 install lxml
soup=BeautifulSoup(html_doc,'lxml')

# print(soup.prettify()) # 对html进行美化

#1 遍历文档树之  .  遍历    速度快
# print(soup.title)
# print(soup.body.p)
# print(soup.body.p.b)

#2、获取标签的名称
# print(soup.title.name)
# print(soup.body.name)
#3、获取标签的属性
# print(soup.body.p)
# print(soup.p['class'])  # 因为class可能有多个，所以是列表
# print(soup.p['id'])
# print(soup.p.attrs) # 所有属性放到字典中

#4、获取标签的内容--文本内容
# print(soup.p.text)  # 当前标签和子子孙的文本内容拼到一起
# print(soup.p.string) # 当前标签只有文本或只有一个子有文本才拿出来，如果有多个子子孙孙，返回None
# print(list(soup.p.strings)) # 把子子孙孙的文本内容放到generator

#5、嵌套选择
# 可以连续点嵌套选择
# print(soup.head.title.string)

#6、子节点、子孙节点
# print(soup.p.contents) #p下所有子节点，放到列表中
# print(list(soup.p.children)) #得到一个迭代器,包含p下所有子节点,跟contents本质一样，只是节约内存
# print(list(soup.p.descendants)) #获取子孙节点,p下所有的标签都会选择出来  子子孙孙


# for i,child in enumerate(soup.p.children):
#     print(i,child)
# for i,child in enumerate(soup.p.descendants):
#     print(i,child)
#7、父节点、祖先节点
# print(soup.a.parent) #获取a标签的父节点
# print(list(soup.a.parents)) #找到a标签所有的祖先节点，父亲的父亲，父亲的父亲的父亲...
#8、兄弟节点

print(soup.a.next_sibling) #下一个兄弟
print(soup.a.previous_sibling) #上一个兄弟

print(list(soup.a.next_siblings)) #下面的兄弟们=>生成器对象
print(soup.a.previous_siblings) #上面的兄弟们=>生成器对象



# . 遍历  
# 取属性 [] attrrs.get()
# 取文本  text  string  strings

bs4搜索文档树

from bs4 import BeautifulSoup

html_doc = """
<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" id="id_p">lqz<b>The Dormouse's story</b></p>

<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" class="sister" id="link1">Elsie</a>,
<a href="http://example.com/lacie" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>

<p class="story">...</p>
"""
soup = BeautifulSoup(html_doc, 'lxml')


# 1、五种过滤器: 字符串、正则表达式、列表、True、方法
# find：找到第一个      find_all：找所有

# 字符串  --->value值是字符串
# res=soup.find_all(name='p')
# res=soup.find(id='id_p')
# res=soup.find_all(class_='story')
# res=soup.find_all(name='p',class_='story')  # and条件
# res=soup.find(name='a',id='link2').text
# res=soup.find(name='a',id='link2').attrs.get('href')
# res=soup.find(attrs={'id':'link2','class':'sister'}).attrs.get('href')
# print(res)


# 正则表达式--->value是正则表达式
# import re
#
# # res=soup.find_all(name=re.compile('^b'))
# # res=soup.find_all(href=re.compile('^http'))
# res=soup.find_all(class_=re.compile('^s'))
# print(res)


# 列表  value值是列表
# res=soup.find_all(name=['body','a'])
# res=soup.find_all(class_=['sister','story'])
# res=soup.find_all(id=['link2','link3'])
# print(res)

# True   value值是True
# res=soup.find_all(name=True)
# res=soup.find_all(id=True)
# res=soup.find_all(href=True)
# print(res)


# 方法

# def has_class_but_no_id(tag):
#     return tag.has_attr('class') and not tag.has_attr('id')
#
# print(soup.find_all(name=has_class_but_no_id))  # 有class但是没有id的标签


#1 html页面中，只要有的东西，通过bs4都可以解析出来
#2 遍历文档树+搜索文档树混用
# def has_class_but_no_id(tag):
#     return tag.has_attr('class') and not tag.has_attr('id')
# print(soup.find(name=has_class_but_no_id).a.text)

# 3 find_all的其他参数limit:限制取几条  recursive：是否递归查找

# def has_class_but_no_id(tag):
#     return tag.has_attr('class') and not tag.has_attr('id')
# res=soup.find_all(name=has_class_but_no_id,limit=1)
#
# print(res)
#
# res=soup.find_all(name='a',recursive=False)  #不递归查找,速度快，只找一层
# print(res)

标签：name,bs4,res,id,soup,模块,print,find
来源： https://www.cnblogs.com/892572624A/p/16251343.html