爬取某图片网站多页图片的python爬虫

# coding=utf-8import requestsimport refrom lxml import etreeimport timeimport sysreload(sys)sys.setdefaultencoding("utf-8") #定义一个爬虫class spider(object):    def __init__(self):        print u'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):        now_page = int(re.search('index_(\d+)',url,re.S).group(1))   #可修改        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        for each in pic_url:            print 'now downloading:' + 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 u'正在处理页面：' + link        html = picspider.getsource(link)        pic_url = picspider.getpic(html)        picspider.savepic(pic_url) time1=time.time()if __name__ == '__main__':    url = 'http://www.ivsky.com/tupian/ziranfengguang/index_1.html'   #可修改    picspider = spider()    all_links = picspider.changepage(url,3)     #可修改    for link in all_links:        picspider.ppic(link)time2=time.time()print u'耗时:'+str(time2-time1)