MAC系统下用pydev环境找不到下载的图片

# coding:UTF8

import urllib2#导入模块

import re

import os

req = urllib2.urlopen('http://www.imooc.com/course/list')

buf = req.read()

listurl = re.findall(r'http：.+\.jpg',buf)

i=0

for url in listurl:

    f = open(str(i)+'.jpg','w')

    req = urllib2.urlopen(url)

    buf = req.read()

    f.write(buf)

    i += 1