Python爬虫中的并发编程详解

"""
example04.py - 单线程版本爬虫
"""
import os
import requests
def download_picture(url):
    filename = url[url.rfind('/') + 1:]
    resp = requests.get(url)
    if resp.status_code == 200:
        with open(f'images/beauty/{filename}', 'wb') as file:
            file.write(resp.content)
def main():
    if not os.path.exists('images/beauty'):
        os.makedirs('images/beauty')
    for page in range(3):
        resp = requests.get(f'<https://image.so.com/zjl?ch=beauty&sn=>{page * 30}')
        if resp.status_code == 200:
            pic_dict_list = resp.json()['list']
            for pic_dict in pic_dict_list:
                download_picture(pic_dict['qhimg_url'])
if __name__ == '__main__':
    main()

"""
example05.py - 多线程版本爬虫
"""
import os
from concurrent.futures import ThreadPoolExecutor
import requests
def download_picture(url):
    filename = url[url.rfind('/') + 1:]
    resp = requests.get(url)
    if resp.status_code == 200:
        with open(f'images/beauty/{filename}', 'wb') as file:
            file.write(resp.content)
def main():
    if not os.path.exists('images/beauty'):
        os.makedirs('images/beauty')
    with ThreadPoolExecutor(max_workers=16) as pool:
        for page in range(3):
            resp = requests.get(f'<Https://image.so.com/zjl?ch=beauty&sn=>{page * 30}')
            if resp.status_code == 200:
                pic_dict_list = resp.json()['list']
                for pic_dict in pic_dict_list:
                    pool.submit(download_picture, pic_dict['qhimg_url'])
if __name__ == '__main__':
    main()

"""
example06.py - 异步I/O版本爬虫
"""
import asyncio
import json
import os
import aiofile
import aiohttp
async def download_picture(session, url):
    filename = url[url.rfind('/') + 1:]
    async with session.get(url, ssl=False) as resp:
        if resp.status == 200:
            data = await resp.read()
            async with aiofile.async_open(f'images/beauty/{filename}', 'wb') as file:
                await file.write(data)
async def main():
    if not os.path.exists('images/beauty'):
        os.makedirs('images/beauty')
    async with aiohttp.ClientSession() as session:
        tasks = []
        for page in range(3):
            resp = await session.get(f'<https://image.so.com/zjl?ch=beauty&sn=>{page * 30}')
            if resp.status == 200:
                pic_dict_list = (await resp.json())['list']
                for pic_dict in pic_dict_list:
                    tasks.append(asyncio.ensure_future(download_picture(session, pic_dict['qhimg_url'])))
        await asyncio.gather(*tasks)
if __name__ == '__main__':
    loop = asyncio.get_event_loop()
    loop.run_until_complete(main())