Python crawler series-start into the soil (1)

python series-start into the soil (1)

I also wrote a blog about crawlers before, you can refer to:
crawler IP proxy pool code record

python crawler crawling network novel

Python crawler practice crawling information

Python crawler experiment pageviews-cool

Crawler (crawling web pages, simulating browsers, setting timeouts, HTTP requests)

Avoid crawling illegal

Optimize your program from time to time to avoid interference with the normal operation of the visited website
When using and disseminating the crawled data, review the captured content. If you find that sensitive content such as user privacy, trade secrets, etc., you need to stop the crawling or dissemination in time

Classification of crawlers in usage scenarios

Common reptile

An important part of the crawling system, which captures a whole page of data

Focus crawler

Built on the basis of general crawlers. Crawl is a specific part of the page

Incremental crawler

Check the status of data updates in the website. Only crawl the latest updated content from the website

Reptiles Anti-reptiles

Anti-climb mechanism

Portal websites can prevent crawlers from crawling website data by formulating corresponding strategies or technical means

Anti-anti-climbing strategy

The crawler program can crack the anti-crawling mechanism in the portal website by formulating relevant strategies or technical means, so as to obtain the portal website information

robots.txt protocol

Gentleman agreement. It specifies which data in the website can be crawled by crawlers and which data cannot be crawled

You can enter /robots.txt after the website name to view the robots agreement of the website
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Common request headers and response headers

Request header

User-Agent

The identity of the request carrier, such as Google Chrome

Connection

After the request is completed, whether to disconnect or keep connected

Response header

Content-Type

The type of data the server responds back to the client

requests module

A native module based on network requests in python, which is very powerful, simple and fast, and extremely efficient

作用：模拟浏览器发送请求

Steps for usage:

Specified url
Initiate a request
Get response data
Persistent storage

download:pip install requests

example:

import requests

# 下载一个网页

url = 'http://www.linlida.com/0_646/'
# 模拟浏览器发送HTTP请求
response = requests.get(url)
response.encoding='gbk'
print(response.encoding)
# print(response.text)
# 持久化存储
with open('./requestsDemo.html', 'w', encoding='utf-8') as fp:
    fp.write(response.text)

effect:
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Crawl the search result page corresponding to the entry made by Sogou (simple webpage collector)

Code:

import requests
import random

# UA 伪装
# User-Agent(请求载体):门户网站的服务器会检测对于请求的载体身份表示,如果检测到请求的载体身份为某一款浏览器,当前的请求一定是正常的请求
user_agent_list=[
            'Mozilla/5.0(compatible;MSIE9.0;WindowsNT6.1;Trident/5.0)',
            'Mozilla/4.0(compatible;MSIE8.0;WindowsNT6.0;Trident/4.0)',
            'Mozilla/4.0(compatible;MSIE7.0;WindowsNT6.0)',
            'Opera/9.80(WindowsNT6.1;U;en)Presto/2.8.131Version/11.11',
            'Mozilla/5.0(WindowsNT6.1;rv:2.0.1)Gecko/20100101Firefox/4.0.1',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER',
            'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E)',
            'Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 SE 2.X MetaSr 1.0',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Maxthon/4.4.3.4000 Chrome/30.0.1599.101 Safari/537.36',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 UBrowser/4.0.3214.0 Safari/537.36',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36 OPR/26.0.1656.60',
            'Opera/8.0 (Windows NT 5.1; U; en)',
            'Mozilla/5.0 (Windows NT 5.1; U; en; rv:1.8.1) Gecko/20061208 Firefox/2.0.0 Opera 9.50',
            'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 9.50',
            'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0',
            'Mozilla/5.0 (X11; U; Linux x86_64; zh-CN; rv:1.9.2.10) Gecko/20100922 Ubuntu/10.10 (maverick) Firefox/3.6.10',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version/5.1.7 Safari/534.57.2',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36',
            'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11',
            'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.133 Safari/534.16',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.11 TaoBrowser/2.0 Safari/536.11',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER',
            'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; LBBROWSER)',
            'Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 SE 2.X MetaSr 1.0',
            'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SV1; QQDownload 732; .NET4.0C; .NET4.0E; SE 2.X MetaSr 1.0)',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 UBrowser/4.0.3214.0 Safari/537.36'
        ]

if __name__ == '__main__':
    url = 'https://www.sogou.com/web'
    # 处理url携带参数，封装到字典中
    kw = input('输入搜索内容: ')
    param = {
    
    
        'query': kw
    }
    header = {
    
    
        'User-Agent': random.choice(user_agent_list)
    }
    # 对指定的url发起的请求对应的url是携带参数的，并且请求过程中处理了参数
    response = requests.get(url, param, headers=header)
    page_text = response.text
    fileName = kw + '.html'
    with open(fileName, 'w', encoding='utf-8') as fp:
        fp.write(response.text)
    print(fileName, '保存成功')

effect:
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Crack Baidu translation

Analysis: Each time you enter content, the page will be refreshed partially. After network analysis, it is found that sugs are passed to each other and send ajax requests
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Code:

import requests
import random
import json

user_agent_list=[
            'Mozilla/5.0(compatible;MSIE9.0;WindowsNT6.1;Trident/5.0)',
            'Mozilla/4.0(compatible;MSIE8.0;WindowsNT6.0;Trident/4.0)',
            'Mozilla/4.0(compatible;MSIE7.0;WindowsNT6.0)',
            'Opera/9.80(WindowsNT6.1;U;en)Presto/2.8.131Version/11.11',
            'Mozilla/5.0(WindowsNT6.1;rv:2.0.1)Gecko/20100101Firefox/4.0.1',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER',
            'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; QQDownload 732; .NET4.0C; .NET4.0E)',
            'Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 SE 2.X MetaSr 1.0',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Maxthon/4.4.3.4000 Chrome/30.0.1599.101 Safari/537.36',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 UBrowser/4.0.3214.0 Safari/537.36',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36 OPR/26.0.1656.60',
            'Opera/8.0 (Windows NT 5.1; U; en)',
            'Mozilla/5.0 (Windows NT 5.1; U; en; rv:1.8.1) Gecko/20061208 Firefox/2.0.0 Opera 9.50',
            'Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; en) Opera 9.50',
            'Mozilla/5.0 (Windows NT 6.1; WOW64; rv:34.0) Gecko/20100101 Firefox/34.0',
            'Mozilla/5.0 (X11; U; Linux x86_64; zh-CN; rv:1.9.2.10) Gecko/20100922 Ubuntu/10.10 (maverick) Firefox/3.6.10',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/534.57.2 (KHTML, like Gecko) Version/5.1.7 Safari/534.57.2',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.71 Safari/537.36',
            'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.64 Safari/537.11',
            'Mozilla/5.0 (Windows; U; Windows NT 6.1; en-US) AppleWebKit/534.16 (KHTML, like Gecko) Chrome/10.0.648.133 Safari/534.16',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/536.11 (KHTML, like Gecko) Chrome/20.0.1132.11 TaoBrowser/2.0 Safari/536.11',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.1 (KHTML, like Gecko) Chrome/21.0.1180.71 Safari/537.1 LBBROWSER',
            'Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0; SLCC2; .NET CLR 2.0.50727; .NET CLR 3.5.30729; .NET CLR 3.0.30729; Media Center PC 6.0; .NET4.0C; .NET4.0E; LBBROWSER)',
            'Mozilla/5.0 (Windows NT 5.1) AppleWebKit/535.11 (KHTML, like Gecko) Chrome/17.0.963.84 Safari/535.11 SE 2.X MetaSr 1.0',
            'Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; Trident/4.0; SV1; QQDownload 732; .NET4.0C; .NET4.0E; SE 2.X MetaSr 1.0)',
            'Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/38.0.2125.122 UBrowser/4.0.3214.0 Safari/537.36'
        ]

if __name__ == '__main__':
    post_url = 'https://fanyi.baidu.com/sug'
    # post请求参数处理
    data = {
    
    
        'kw': 'cat'
    }
    header = {
    
    
        'User-Agent': random.choice(user_agent_list)
    }
    response = requests.post(post_url, data, headers=header)
    # 获取响应数据： json()方法返回的是obj对象 (如果确认响应数据是json类型的，才可以使用json()方法)
    page_json = response.json()
    print(page_json)
    # 持久化存储
    fp = open('./cat.json','w', encoding='utf-8');
    json.dump(page_json, fp=fp, ensure_ascii=False)
    print('cat.json保存成功')