python学习--抓取一个网页上图片

 #!/bin/python
 # download_pic.py
 # download picture
 import os
 import sys
 from urllib.request import urlopen

 url = sys.argv[1]
 page = urlopen(url)
 #需要指定编码格式
 html = str(page.read(),encoding='utf8')
 page.close()

 #create directory
 if os.path.exists("./picture") == False:
     os.makedirs('./picture')
     os.chdir('./picture')

 head = html.find('<img')
 while head != -1:
     html = html[head:]
     http_idx = html.find('http')
     if http_idx == -1:
         break
     html = html[http_idx:]
     tail = html.find('"')
     url = html[:tail]

     print("url:", url)
     cmd = "wget {0}".format(url)
     os.system(cmd)
     print ("cmd:", cmd)
     #html = page2[tail:]
     head = html.find('<img')

用法： python download_pic.py http://image.baidu.com/