UnicodeDecodeError: 'utf-8' codec can'

问题:

I am trying to scrap a picture from the link and put it into a image file. The request response is returning a byte stream. So I am using decode('utf-8') to convert to unicode stream however, I am facing the following error:

print (info.decode(('utf-8')))

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xff in position 0: invalid start byte

    from urllib import request
    img = request.urlopen('http://www.py4inf.com/cover.jpg')
    fhand = open('cover.jpg', 'w')
    size = 0
    while True:
        info = img.read(100000)
        if len(info) < 1 : break
        size = size + len(info)
        print (info.decode(('utf-8')))
        fhand.write(info.decode(('utf-8')))

    print (size,'characters copied.')
    fhand.close()

Please let me know how can I proceed. Thanks.

回答1:

The file should be opened in binary mode and then you can copy the stream byte for byte. Since shutil already has a handy helper utility, you can

import shutil
import os
from urllib import request

img = request.urlopen('http://www.py4inf.com/cover.jpg')
with open('cover.jpg', 'wb') as fhand:
    shutil.copyfileobj(img, fhand)
print(os.stat('cover.jpg').st_size, 'characters copied')

回答2:

Don't use Unicode transformations for JPG images.

Unicode is for text. What you are downloading is not text, it is something else.

Try this:

from urllib import request
img = request.urlopen('http://www.py4inf.com/cover.jpg')
fhand = open('cover.jpg', 'wb')
size = 0
while True:
    info = img.read(100000)
    if len(info) < 1 : break
    size = size + len(info)
    fhand.write(info)

print (size,'characters copied.')

Or, more simply:

from urllib import request
request.urlretrieve('http://www.py4inf.com/cover.jpg', 'cover.jpg')