Python：asyncio 库高级用法举例和应用详解

import asyncio

import asyncio  # 导入asyncio库
import aiohttp  # 导入aiohttp库，用于异步HTTP请求

async def fetch_url(session, url):
    # 定义一个异步函数，用于从指定URL获取内容
    async with session.get(url) as response:
        return await response.text()  # 等待并返回响应内容

async def main(urls):
    # 定义主异步函数，用于处理多个URL
    async with aiohttp.ClientSession() as session:
        tasks = [fetch_url(session, url) for url in urls]  # 创建任务列表
        return await asyncio.gather(*tasks)  # 并发运行所有任务并等待结果

# 定义需要抓取的URL列表
urls = ["https://example.com", "https://httpbin.org/get"]

# 运行异步函数并获取结果
results = asyncio.run(main(urls))
for url, content in zip(urls, results):
    print(f"Content from {url}: {content[:100]}")  # 打印前100字符

import asyncio  # 导入asyncio库

async def handle_client(reader, writer):
    # 处理客户端连接的异步函数
    data = await reader.read(100)  # 读取客户端发送的数据
    message = data.decode()  # 解码数据
    addr = writer.get_extra_info('peername')  # 获取客户端地址信息
    print(f"Received {message} from {addr}")

    print("Send: %r" % message)
    writer.write(data)  # 回写数据
    await writer.drain()  # 等待数据完全写出

    print("Close the connection")
    writer.close()  # 关闭连接
    await writer.wait_closed()  # 等待连接关闭

async def main():
    # 创建服务器并开始监听
    server = await asyncio.start_server(handle_client, '127.0.0.1', 8888)
    async with server:
        await server.serve_forever()  # 异步运行服务器

# 运行服务器
asyncio.run(main())

import asyncio  # 导入asyncio库
import asyncpg  # 导入asyncpg，用于异步数据库连接

async def fetch_data():
    # 连接到数据库并执行查询
    conn = await asyncpg.connect(user='user', password='password', database='test', host='127.0.0.1')
    rows = await conn.fetch('SELECT * FROM my_table')
    await conn.close()  # 关闭数据库连接
    return rows

# 运行异步函数并获取结果
rows = asyncio.run(fetch_data())
for row in rows:
    print(row)  # 打印每一行查询结果