Python爬取pdf（优化版2）v3.0

平均用时为第二个版本的0.5 - 2/3。

import requests
res = requests.get('http://lxml.de/lxmldoc-4.1.1.pdf', stream=True)
with open('./lxml.pdf', 'wb') as f:
    for chunk in res.iter_content(chunk_size=10 * 1024 * 1024):
        if chunk:
            f.write(chunk)