使用requests爬取梨视频、bilibili视频、汽车之家，bs4遍历文档树、搜索文档树，css选择器

今日内容概要

• 使用requests爬取梨视频
• requests+bs4爬取汽车之家
• bs4遍历文档树
• bs4搜索文档树
• css选择器

内容详细

1、使用requests爬取梨视频

# 模拟发送http请求的库：requests---》只能发送http请求----》没有解析库--》re、bs4、lxml
# requests-html：发送请求+解析xml

# 视频m3u8格式，分段---》会员试看6分钟---》只加载了6分钟
# 收费视频：视频解析

### 完整的视频文件保存到本地

# re 解析想要的数据
# import requests
# res=requests.get("https://www.pearvideo.com/")
# print(res.text)

### 爬取到的视频文件放到本地 video 目录下
# https://www.pearvideo.com/category_loading.jsp?reqType=5&categoryId=8&start=24

import requests
import re

res = requests.get('https://www.pearvideo.com/category_loading.jsp?reqType=5&categoryId=8&start=24')
# print(res.text)

# 解析出页面中所有的视频地址
video_list = re.findall('<a href="(.*?)" class="vervideo-lilink actplay">', res.text)
# print(video_list)

for video in video_list:
    video_url = 'https://www.pearvideo.com/' + video
    video_id = video_url.split('_')[-1]
    header = {
        'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.74 Safari/537.36',
        'Referer': video_url
    }
    # 第一层反扒是加refer
    res_video = requests.get('https://www.pearvideo.com/videoStatus.jsp?contId=%s&mrd=0.7113776105084832' % video_id,
                             headers=header)
    mp4_url = res_video.json()['videoInfo']['videos']['srcUrl']

    # 第二层反扒是把不能播放地址变成能播放地址
    mp4_url = mp4_url.replace(mp4_url.split('/')[-1].split('-')[0], 'cont-%s' % video_id)
    print(mp4_url)

    # 下载到本地
    res_video_detail = requests.get(mp4_url)
    with open('./video/%s.mp4' % video_id, 'wb') as f:
        for line in res_video_detail.iter_content(1024):
            f.write(line)

# 单线程下载，速度不快，全是io操作，开启多线程能够显著提高速度---》使用多线程全站下载视频
# 线程池整站爬取

# 不能播放的地址
# https://video.pearvideo.com/mp4/third/20220314/    1652060493892      -10097838-231626-hd.mp4  # 不正常地址
# https://video.pearvideo.com/mp4/third/20220314/    cont-1754713       -10097838-231626-hd.mp4  # 正常地址

# mp4_url='https://video.pearvideo.com/mp4/third/20220314/      1652060493892   -10097838-231626-hd.mp4'
# mp4_url=mp4_url.replace(mp4_url.split('/')[-1].split('-')[0],'cont-%s'%video_id)

2、爬取bilibili视频

# 爬取的b站视频保存到本地 是分为两个文件：
	视频文件
	音频文件

# 通过第三方软件做了整合之后才是完整的视频

# 视频去水印--》fmmpeg--》加水印，拼接裁剪，抠图，转码。。。
# 装上使用python来调用处理

# 导入requests模块，模拟发送请求
import requests
# 导入json
import json
# 导入re
import re

# 定义请求头
headers = {
    'Accept': '*/*',
    'Accept-Language': 'en-US,en;q=0.5',
    'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.84 Safari/537.36'
}

# 正则表达式，根据条件匹配出值
def my_match(text, pattern):
    match = re.search(pattern, text)
    print(match.group(1))
    print()
    return json.loads(match.group(1))

def download_video(old_video_url, video_url, audio_url, video_name):
    headers.update({"Referer": old_video_url})
    print("开始下载视频：%s" % video_name)

    video_content = requests.get(video_url, headers=headers)
    print('%s视频大小：' % video_name, video_content.headers['content-length'])

    audio_content = requests.get(audio_url, headers=headers)
    print('%s音频大小：' % video_name, audio_content.headers['content-length'])

    # 下载视频开始
    received_video = 0
    with open('%s_video.mp4' % video_name, 'ab') as output:
        while int(video_content.headers['content-length']) > received_video:
            headers['Range'] = 'bytes=' + str(received_video) + '-'
            response = requests.get(video_url, headers=headers)
            output.write(response.content)
            received_video += len(response.content)
    # 下载视频结束

    # 下载音频开始
    audio_content = requests.get(audio_url, headers=headers)
    received_audio = 0
    with open('%s_audio.mp4' % video_name, 'ab') as output:
        while int(audio_content.headers['content-length']) > received_audio:
            # 视频分片下载
            headers['Range'] = 'bytes=' + str(received_audio) + '-'
            response = requests.get(audio_url, headers=headers)
            output.write(response.content)
            received_audio += len(response.content)
    # 下载音频结束
    return video_name

if __name__ == '__main__':
    # 换成你要爬取的视频地址
    url = 'https://www.bilibili.com/video/BV17F411M7pQ'

    # 发送请求，拿回数据
    res = requests.get(url, headers=headers)

    # 视频详情json
    playinfo = my_match(res.text, '__playinfo__=(.*?)</script><script>')

    # 视频内容json
    initial_state = my_match(res.text, r'__INITIAL_STATE__=(.*?);\(function\(\)')

    # 视频分多种格式，直接取分辨率最高的视频 1080p
    video_url = playinfo['data']['dash']['video'][0]['baseUrl']

    # 取出音频地址
    audio_url = playinfo['data']['dash']['audio'][0]['baseUrl']
    video_name = initial_state['videoData']['title']
    print('视频名字为：video_name')
    print('视频地址为：', video_url)
    print('音频地址为：', audio_url)
    download_video(url, video_url, audio_url, video_name)

3、requests+bs4爬取汽车之家

### 爬取到的图片都会保存到本地

### 也可以在pycharm直接打印出 新闻地址 和 图片地址 单独访问

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

4、bs4遍历文档树(快速定位查找)

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    第三方的，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 美化成完整的书写格式

# 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)  # title
print(soup.body.name)  # body

# 3、获取标签的属性
print(soup.body.p)  # 找 p标签 速度快些
print(soup.p['class'])  # ['title']  因为class可能有多个，所以是列表
print(soup.p['id'])  # id_p
print(soup.p.attrs)  # {'class': ['title'], 'id': 'id_p'}  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)  # lqzThe Dormouse's story 当前标签和子子孙的文本内容拼到一起
print(soup.p.string)  # None  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))  # ['lqz', "The Dormouse's story"]  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)  # The Dormouse's story

# 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

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

5、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')

##### 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

# 1、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)

# 2、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)

# 3、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)

# 4、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)

# 5、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

### 补充总结：
# 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)

6、css选择器

### css，xpath选择器是通用的---》基本所有的解析库(bs4,lxml,pyquery,selenium的解析库)--->都支持css选择器-->css在前端通用

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')

# soup.select()  # 找所有
# soup.select_one()  # 找一个

'''
div  找div标签
div>a  找div下的紧邻的a
div a  找div下的子子孙孙的a
.sister  找类名为sister的标签
#id_p    找id为id_p的标签
'''

# res = soup.select('#id_p')
# res = soup.select('.sister')
res = soup.select_one('.story>a').attrs.get('href')
print(res)

# 终极大招
import requests

response = requests.get('https://www.runoob.com/cssref/css-selectors.html')
soup = BeautifulSoup(response.text, 'lxml')
res = soup.select_one('#content > table > tbody > tr:nth-child(2) > td:nth-child(3)').text  # 找到标签 右键 copy--selector
print(res)

# 只要页面中有的通过bs4都能解析出来