Python uses asyncio to implement coroutines for writing asynchronous functions and handling asynchronous events

Environmental construction and preparation work: 1. Install Python 3.5 or above, as asyncio was introduced from Python 3.5 onwards. 2. Install asyncio and other related dependency libraries. Dependent class libraries: 1. asyncio: Python Standard library, used to write asynchronous code. 2. aiohttp: Asynchronous HTTP client/server library used to send HTTP requests and process responses. 3. Beautiful soup4: A library for parsing HTML/XML, used to extract data from web pages. 4. aiofiles: File read and write library, used to read and write files in asynchronous environments. 5. UVloop (optional): A library that replaces asyncio event loops, providing higher performance. The complete sample code is as follows: python import asyncio import aiohttp from bs4 import BeautifulSoup import aiofiles async def fetch_html(url): async with aiohttp.ClientSession() as session: async with session.get(url) as response: return await response.text() async def parse_html(html): soup = BeautifulSoup(html, 'html.parser') return soup.find('title').text.strip() async def save_result(result): async with aiofiles.open('result.txt', 'w') as file: await file.write(result) async def main(): url = 'https://www.example.com' html = await fetch_html(url) result = await parse_html(html) await save_result(result) if __name__ == '__main__': asyncio.run(main()) Code Interpretation: 1. Fetch_ The HTML function uses the aiohttp library to send HTTP requests and return the text content of the response. 2. parse_ The HTML function uses the beautiful soup4 library to parse HTML and extract title information. 3. Save_ The result function asynchronously writes the result to a file using the aiofiles library. The main function is the entry point for the entire asynchronous process, calling the three asynchronous functions in sequence. Summary: Through the asyncio library, we can easily write asynchronous code, implement coroutines, handle asynchronous events, and improve program efficiency and performance. In practical projects, we can utilize asyncio and related class libraries to handle time-consuming operations such as network requests, parsing HTML/XML, and reading and writing files.