使用AIOHTTP模块：提高网络请求效率

链接：https://pan.quark.cn/s/c6df12a6efcc​

本文将介绍如何利用AIOHTTP模块提高网络请求效率，以及如何编写一个异步下载图片的程序，并展示如何通过AIOHTTP和AIO files的异步功能优化Python爬虫程序的读写操作。

00:00 - AIOHTTP模块：提高网络请求效率

AIOHTTP模块作为一种异步网络请求库，与传统的同步请求模块相比，能够显著提高网络请求的效率。下面是一个简单的示例，展示了如何使用AIOHTTP进行图片下载。

安装AIOHTTP

首先，确保已安装AIOHTTP模块，可以使用以下命令进行安装：

pip install aiohttp

编写异步下载图片的程序

我们将定义一个名为​​download​​的协程函数用于下载图片，并在主程序中使用异步方法来调用该函数。

import aiohttp
import asyncio
import aiofiles

async def download(url, session, dest):
    async with session.get(url) as response:
        if response.status == 200:
            f = await aiofiles.open(dest, mode='wb')
            await f.write(await response.read())
            await f.close()
            print(f"Downloaded {url} to {dest}")
        else:
            print(f"Failed to download {url}")

async def main(urls):
    async with aiohttp.ClientSession() as session:
        tasks = []
        for idx, url in enumerate(urls):
            dest = f"image_{idx}.jpg"
            task = asyncio.create_task(download(url, session, dest))
            tasks.append(task)
        await asyncio.gather(*tasks)

if __name__ == "__main__":
    image_urls = [
        "http://example.com/image1.jpg",
        "http://example.com/image2.jpg",
        "http://example.com/image3.jpg"
    ]
    asyncio.run(main(image_urls))

04:51 - 调用AIOHTTP模块实现图片下载

使用AIOHTTP模块通过client session方法发起请求，并利用异步IO实现图片的下载与保存。以下是示例代码：

import aiohttp
import asyncio
import aiofiles

async def fetch_and_save(url, session, path):
    async with session.get(url) as response:
        if response.status == 200:
            async with aiofiles.open(path, 'wb') as f:
                await f.write(await response.read())
                print(f"Saved image from {url} to {path}")
        else:
            print(f"Failed to fetch image from {url}")

async def download_images(urls):
    async with aiohttp.ClientSession() as session:
        tasks = []
        for idx, url in enumerate(urls):
            path = f'image_{idx}.jpg'
            task = asyncio.create_task(fetch_and_save(url, session, path))
            tasks.append(task)
        await asyncio.gather(*tasks)

if __name__ == '__main__':
    image_urls = [
        "http://example.com/image1.jpg",
        "http://example.com/image2.jpg",
        "http://example.com/image3.jpg"
    ]
    asyncio.run(download_images(image_urls))

09:30 - 使用AIO异步功能提高Python爬虫效率

下面展示如何利用AIOHTTP和AIO files的异步功能优化Python爬虫程序的读写操作。

安装依赖

确保已安装aiohttp和aiofiles模块。

pip install aiohttp aiofiles

编写异步爬虫程序

import aiohttp
import asyncio
import aiofiles

async def fetch_page(url, session):
    async with session.get(url) as response:
        if response.status == 200:
            return await response.text()
        else:
            print(f"Failed to fetch {url}")
            return None

async def save_page(content, path):
    async with aiofiles.open(path, 'w') as f:
        await f.write(content)
        print(f"Saved page to {path}")

async def crawl(urls):
    async with aiohttp.ClientSession() as session:
        tasks = []
        for idx, url in enumerate(urls):
            path = f'page_{idx}.html'
            task = asyncio.create_task(fetch_and_save(url, session, path))
            tasks.append(task)
        await asyncio.gather(*tasks)

async def fetch_and_save(url, session, path):
    content = await fetch_page(url, session)
    if content:
        await save_page(content, path)

if __name__ == "__main__":
    urls = [
        "http://example.com/page1",
        "http://example.com/page2",
        "http://example.com/page3"
    ]
    asyncio.run(crawl(urls))

上述代码展示了如何使用AIOHTTP和AIO files的异步功能来获取网页内容并将其保存至本地文件中。通过引入异步I/O处理，大幅提升了数据处理速度与程序响应性。

通过这些示例，您可以深入理解并应用Python的异步编程机制，以提升程序执行效率。