Python3下载网页中的图片

import urllib.request
import re
req = urllib.request.urlopen('http://www.imooc.com/')
buf = req.read()
webstr = buf.decode()
urlList = re.findall(r'http:.+\.jpg', webstr);
i = 0
for url in urlList:
    f = open(str(i)+'.jpg','wb') #注意第二个参数要写成wb，写成w会报错
    req = urllib.request.urlopen(url)
    buf = req.read()
    #bufstr = buf.decode('utf-8','ignore')
    f.write(buf)
    i += 1