What do you need to learn about python crawlers?

Python crawler is a technology that automatically obtains data on the Internet by writing programs. Learning Python crawlers requires some basic knowledge and skills. The following are important contents you need to master when learning Python crawlers:

1. Basic knowledge of Python: As a technology written in Python language, learning Python crawlers first requires mastering the basic knowledge of Python, including data types, variables, Conditional statements, loop statements, functions, etc.

2. Basic network knowledge: Understand basic network protocols and communication principles, such as HTTP protocol, URL structure, request and response, etc. This knowledge helps to understand how crawlers work and how they are implemented.

3. Basic knowledge of HTML and CSS: HTML is the markup language for building web pages, and CSS is the style sheet language used to control the style of web pages. Learning Python crawler requires understanding the basic syntax and common tags of HTML and CSS so that you can parse and extract web page content.

4. Regular expressions: Regular expressions are a powerful tool for matching and processing text. In crawlers, regular expressions are often used to extract required data from the source code of web pages.

5. XPath and CSS selectors: XPath is a language for locating nodes in XML documents, and CSS selectors are a syntax for selecting elements in HTML documents. Learning XPath and CSS selectors can make it easier to locate and extract data from web pages.

6. Data storage and processing: The data obtained by the crawler usually needs to be stored and processed. Learning Python crawlers requires understanding how to use databases, files, or other data storage methods to save crawled data, and learning how to use Python for data processing and analysis.

7. Crawler frameworks and libraries: Python has many powerful crawler frameworks and libraries, such as Scrapy, BeautifulSoup, Requests, etc. When learning Python crawlers, you can learn and use these frameworks and libraries to simplify the development and maintenance of crawlers.

8. Anti-crawler and camouflage technology: Due to the restrictions and protection of crawlers on websites, learning Python crawlers also requires understanding of some anti-crawler and camouflage technologies to avoid being banned or blocked by the website.

9. Comply with laws and ethics: When learning and using Python crawlers, you need to abide by relevant laws, regulations and ethics, and do not engage in illegal, illegal or infringing crawling behaviors.

To summarize, learning Python crawlers requires mastering Python basics, network basics, HTML and CSS basics, regular expressions, XPath and CSS selectors, data storage and processing, crawler frameworks and libraries, and anti-crawlers and camouflage techniques, while complying with legal and ethical regulations. Through continuous learning and practice, mastering these knowledge and skills will enable you to write efficient, stable and legal Python crawler programs.

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