python3 面向对象编程--类的封装和继承

#python3
import re
from urllib import request
import osclass PosterSpider(object):
     def __init__(self, path='./'):
           self.path = path#the entry of this process
     def getStart(self, url):
           page = self.reqPage(url)           page = page.decode('utf-8')
           for mvname,mvurl in self.getMvInfo(page):
                self.save2File(mvname,mvurl)           nexturl = self.getNextpage(page)
           if nexturl:
               self.getStart(nexturl)#request the page
      def reqPage(self, url):
           response = request.urlopen(url)
           if response.code == 200:
              page = response.read()
              return page#get the fname and url for each mv
       def getMvInfo(self, page):
             urllist = re.findall(r'<img.*alt="(.*?)".*src="(.*?)"',page)
             return urllist#get next page url
       def getNextpage(self, page):
             url = 'https://movie.douban.com/top250'
             nexturlraw = re.findall(r'<link rel="next" href="(.*?)"',page)
             if nexturlraw:
                nexturllast = url + nexturlraw[0]
                return nexturllast#save img to file
    def save2File(self, fname, url):
          image = self.reqPage(url)
          fname = fname + '.jpg'
          fpath = os.path.join(self.path,fname)
          with open(fpath,'wb') as f:
                  f.write(image)if __name__ == '__main__':
    url = 'https://movie.douban.com/top250'
    spider = PosterSpider('img')
    spider.getStart(url)

用一个例子来演示会更加清晰