import os
os.makedirs('./image/', exist_ok=True)
IMAGE_URL = "http://image.nationalgeographic.com.cn/2017/1122/20171122113404332.jpg"
def urllib_download():
from urllib.request import urlretrieve
urlretrieve(IMAGE_URL, './image/img1.png')
def request_download():
import requests
r = requests.get(IMAGE_URL)
with open('./image/img2.png', 'wb') as f:
f.write(r.content)
def chunk_download():
import requests
r = requests.get(IMAGE_URL, stream=True)
with open('./image/img3.png', 'wb') as f:
for chunk in r.iter_content(chunk_size=32):
f.write(chunk)
urllib_download()
print('download img1')
request_download()
print('download img2')
chunk_download()
print('download img3')使用timeout 参数可以设定等待连接的秒数，如果等待超时，Requests会抛出异常
>>> requests.get('http://github.com', timeout=0.001)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
requests.exceptions.Timeout: HTTPConnectionPool(host='github.com', port=80): Request timed out. (timeout=0.001)
>>> requests.get('https://www.baidu.com',timeout=0.5)
<Response [200]>timeout 仅对连接过程有效，与响应体的下载无关。 timeout 并不是整个下载响应的时间限制，而是如果服务器在 timeout 秒内没有应答，将会引发一个异常（更精确地说，是在 timeout 秒内没有从基础套接字上接收到任何字节的数据时)。
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