Understand the use of Python crawlers in two minutes

Python crawler is a web crawler implemented in the Python programming language. It is mainly used for capturing and processing network data. Compared with other languages, Python is very suitable for developing web crawlers. A programming language with a large number of built-in packages that can easily implement web crawler functions.

Python crawlers can do many things, such as search engines, data collection, ad filtering, etc. Python crawlers can also be used for data analysis and can play a huge role in data capture!

Python crawler architecture composition

1. URL manager: manages the url set to be crawled and the url set that has been crawled, and sends the url to be crawled to Web page downloader;

2. Web page downloader: crawl the web page corresponding to the url, store it as a string, and send it to the web page parser;

3. Web page parser: parse out the valuable The data is stored and the URL is added to the URL manager.

Python crawler working principle

The Python crawler uses the URL manager to determine whether there is a URL to be crawled. If there is a URL to be crawled, it is passed to the downloader through the scheduler and downloaded The URL content is sent to the parser through the dispatcher, the process of parsing the URL content, passing the value data and new URL list to the application through the dispatcher, and outputting the value information.

Commonly used frameworks for Python crawlers include:

grab: web crawler framework (based on pycurl/multicur);

scrapy: web crawler framework (based on twisted ), does not support Python3;

pyspider: a powerful crawler system;

cola: a distributed crawler framework;

portia: a visual crawler based on Scrapy;

restkit: HTTP resource toolkit for Python. It allows you to easily access HTTP resources and objects built around it;

demiurge: A crawler microframework based on PyQuery.

Python crawlers have a wide range of applications and are dominant in the field of web crawlers. The application of frameworks such as Scrapy, Request, BeautifulSoap, and urlib can achieve the function of crawling freely. As long as you have data crawling ideas, Python crawlers can do it. accomplish!

Thank you everyone for reading, I hope you will benefit a lot.

This article is reproduced from: https://blog.csdn.net/lmseo5hy/article/details/81740339

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