Python使用asyncio处理异步编程的代码示例

import asyncio

async def say_hello():
    print("Hello")
    await asyncio.sleep(1)
    print("World")

# 获取事件循环并运行异步函数
asyncio.run(say_hello())

import asyncio

async def say_after(delay, message):
    await asyncio.sleep(delay)
    print(message)

async def main():
    task1 = asyncio.create_task(say_after(1, "Hello"))
    task2 = asyncio.create_task(say_after(2, "World"))

    await task1
    await task2

asyncio.run(main())

import aiohttp
import asyncio

async def fetch(url):
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as response:
            return await response.text()

async def main():
    url = 'https://www.example.com'
    html = await fetch(url)
    print(html)

asyncio.run(main())

import asyncio

async def say_hello():
    await asyncio.sleep(2)
    return "Hello, World!"

async def main():
    try:
        result = await asyncio.wait_for(say_hello(), timeout=1)
        print(result)
    except asyncio.TimeoutError:
        print("The coroutine took too long to complete")

asyncio.run(main())

import aiohttp
import asyncio

class AsyncContextManager:
    async def __aenter__(self):
        print("Entering context")
        return self

    async def __aexit__(self, exc_type, exc, tb):
        print("Exiting context")

    async def do_something(self):
        await asyncio.sleep(1)
        print("Doing something")

async def main():
    async with AsyncContextManager() as manager:
        await manager.do_something()

asyncio.run(main())