A reptile principle
1. What is the Internet?
It refers to a stack of a network device, to the computer station to the Internet together with a called Internet.
2. The purpose of the establishment of the Internet?
The purpose is to establish the Internet transfer and data sharing data.
3. What is the data?
For example ... Taobao, Jingdong product information such as
number of securities investment information East Fortune, snowball network ...
the chain of home, such as availability of information freely ....
12306 ticket information ...
4. Internet whole process:
- Common User:
Open Browser -> sending a request to a target site -> the fetch response data -> renderer to the browser
- crawlers:
Analog Browser -> sending a request to a target site -> the fetch response data -> extract valuable data -> persisted to the data
5. What is the browser sends a request?
request http protocol.
- Client:
the browser is a software -> Client IP and port
- server
https://www.jd.com/
www.jd.com (Jingdong domain name) -> DNS parsing -> Jingdong server IP and port
Client ip and port ------> IP and port to send the request to the server can establish a link to obtain the corresponding data.
6. The crawler whole process
- the transmission request (request requires libraries: Requests database request, requesting the Selenium library)
- fetch response data (as long as the transmission request to the server, the request returns response data)
- parses and extracts data (requires parsing library : Re, BeautifulSoup4, Xpath ...)
- save to a local (file processing, database, MongoDB repository)
Two Requests library request
1. Installation and Use
- open cmd
- Input: pip3 install requests
2. crawling video
3. packet capture analysis
Open developer mode browser (check) ----> select the network
to find pages visited suffix xxx.html (response text)
1) the request url (website address access)
2) request method:
GET:
direct sending a request to obtain data
https://www.cnblogs.com/kermitjam/articles/9692597.html
POST:
need to carry user information to the target address to send a request
https://www.cnblogs.com/login
3) response status codes:
2xx: Success
3xx: Redirection
4xx: Can not find resource
5xx: Server Error
4) request header information:
the User-Agent: User Agent (proved to be a request sent by computer equipment and browser)
Cookies: login user real information (to prove users of your target site)
Referer: a url to access the (prove you are Jump from the target sites on the web)
5) Request body:
POST request will have the request body.
The Data Form1
{
'User': 'Tank',
'pwd': '123'
}
For example:
import requests # import request requests Library # Baidu home page to send a request to obtain the response object response = requests.get(url='https://www.baidu.com/') # Set the character encoding to UTF - . 8 response.encoding = ' UTF-. 8 ' # Print the response text print(response.text) # The text is written in response to local with open('baidu.html', 'w', encoding='utf-8') as f: f.write(response.text)
Example 2:
''''''
'''
Video Options:
1. Pears video
'''
import requests
## to the source address of the video transmission request
response = requests.get(
'https://video.pearvideo.com/mp4/adshort/20190625/cont-1570302-14057031_adpkg-ad_hd.mp4')
# # Print binary stream, such as pictures, video and other data
print(response.content)
# # Save the video to your local
with open('视频.mp4', 'wb') as f:
f.write(response.content)
'''
1, first send a request to the pear Video Home
https://www.pearvideo.com/
Id get resolved for all videos:
video_1570302
re.findall()
2, access to video details page url:
Thrilling! Man robbed on the subway slip, go on foot
https://www.pearvideo.com/video_1570302
Secret Karez
https://www.pearvideo.com/video_1570107
'''
import requests
import re # regularization, for parsing text data
1, first send a request to the pear Video Home
response = requests.get('https://www.pearvideo.com/')
print(response.text)
# Re regular matches to get all video id
Parameter # 1: Regular matching rules
Parameter # 2: parse text
Parameter # 3: Match mode
res_list = re.findall('<a href="video_(.*?)"', response.text, re.S)
print(res_list)
# Stitching each video detail page url
for v_id in res_list:
detail_url = 'https://www.pearvideo.com/video_' + v_id
print(detail_url)
# Sending a request to obtain the video source url for each video detail page
response = requests.get(url=detail_url)
# print(response.text)
# Parse and extract details page video url
# Video url
video_url = re.findall('srcUrl="(.*?)"', response.text, re.S)[0]
print(video_url)
# Name video
video_name = re.findall(
'<h1 class="video-tt">(.*?)</h1>', response.text, re.S)[0]
print(video_name)
# Binary stream to acquire a video transmission request video url
v_response = requests.get(video_url)
with open('%s.mp4' % video_name, 'wb') as f:
f.write(v_response.content)
print (video_name, 'video crawling Complete')
Four crawling IMDb
: starting from the current position
*: Find all
:? Not looking to find the first
* ?: non-greedy matching
*: greedy match
(. *?): Extract data in brackets
Movie rankings, movies url, film name, director - starring - the type of movie scores, number of reviews, film synopsis
<div class="item">.*?<em class="">(.*?)</em> .*?<a href="(.*?)">.*?<span class="title">(.*?)</span> .*?导演:(.*?)</p>.*?<span class="rating_num".*?>(.*?)</span> .*?<span>(.*?)人评价</span>.*?<span class="inq">(.*?)</span>
<div class="item"> <div class="pic"> <em class="">226</em> <a href="https://movie.douban.com/subject/1300374/"> <img width="100" alt="绿里奇迹" src="https://img3.doubanio.com/view/photo/s_ratio_poster/public/p767586451.webp" class=""> </a> </div> <div class="info"> <div class="hd"> <a href="https://movie.douban.com/subject/1300374/" class=""> <Span class = "title"> Green Mile </ span> <span class="title"> / The Green Mile</span> <Span class = "other"> / Green Mile (units) / green mile </ span> </a> <span class="playable">[可播放]</span> </div> <div class="bd"> <p class=""> Director: Frank Darabont Starring: Tom Hanks Tom Hanks / David Morse David M ... <br> 1999 / USA / Crime Drama Fantasy Mystery </p> <div class="star"> <span class="rating45-t"></span> <span class="rating_num" property="v:average">8.7</span> <span property="v:best" content="10.0"></span> <Span> 141370 persons evaluated </ span> </div> <p class="quote"> <Span class = "inq"> Angel temporarily leave. </ Span> </p> </div> </div> </div>