这是源代码
# coding=utf-8
import re
import sys
import time
import requests
from lxml import etree
import importlib
importlib.reload(sys)
# 定义一个爬虫
class spider(object):
def __init__(self):
print('开始爬取内容。。。')
# getsource用来获取网页源代码
    def getsource(self, url):
html = requests.get(url)
return html.text
# changepage用来生产不同页数的链接
    def changepage(self, url, total_page):
if re.search('index_(\d+)', url, re.S):
now_page = int(re.search('index_(\d+)', url, re.S).group(1))  # 可修改
        else:
now_page = 0
        page_group = []
for i in range(now_page, total_page + 1):
link = re.sub('index_\d+', 'index_%s' % i, url, re.S)  # 可修改
            page_group.append(link)
return page_group
# getpic用来爬取一个网页图片
    def getpic(self, source):
selector = etree.HTML(source)
pic_url = selector.xpath('//ul[@class="ali"]/li/div/a/img/@src')  # 可修改
        return pic_url
# savepic用来保存结果到pic文件夹中
    def savepic(self, pic_url):
picname = re.findall('(\d+)', link, re.S)  # 可修改
        picnamestr = ''.join(picname)
i = 0
        #------------------------------------------下面这段没有执行！！！-----------------------------------------
        for each in pic_url:
print('now downloading:{}'.format(each))
pic = requests.get(each)
fp = open('pic\\' + picnamestr + '-' + str(i) + '.jpg', 'wb')
fp.write(pic.content)
fp.close()
i += 1
            # ppic集合类的方法
    def ppic(self, link):
print('正在处理页面：{}'.format(link))
html = picspider.getsource(link)
pic_url = picspider.getpic(html)
picspider.savepic(pic_url)
if __name__ == '__main__':
start = time.time()
url = 'http://www.baidu.com/'  # 可修改
    picspider = spider()
all_links = picspider.changepage(url, 3)  # 可修改
    for link in all_links:
picspider.ppic(link)
end = time.time()
print('耗时:{}'.format(start - end))