python实现简单爬虫

用python实现爬取极客网数据。

#-*-coding:utf8-*-
import requests
import re
import sys

reload(sys)
sys.setdefaultencoding("utf-8")

class spider(object):
    def __init__(self):
        print u'开始爬取内容。。。。'

    def getsource(self,url):
        html = requests.get(url)
        return html.text

    def changepage(self,url,total_page):
        now_page = int(re.search('pageNum=(\d+)',url,re.S).group(1))
        page_group = []
        for i in range(now_page,total_page+1):
            link = re.sub('pageNum=\d+','pageNum=%s'%i,url,re.S)
            page_group.append(link)
        return page_group

    def geteveryclass(self,source):
        everyclass = re.findall('<li id="(.*?)</li>',source,re.S)
        return everyclass

    def getinfo(self,eachclass):
        info = {}
        info['title'] = re.search('title="(.*?)alt="',eachclass,re.S).group(1)
        info['content'] = re.search('display: none;">(.*?)</p>',eachclass,re.S).group(1)
        timeandlevel = re.findall('<em>(.*?)</em>',eachclass,re.S)
        info['classtime'] = timeandlevel[0]
        info['classlevel'] = timeandlevel[1]
        info['learnnum'] = re.search('"learn-number">(.*?)</em>',eachclass,re.S).group(1)
        return info

    def saveinfo(self,classinfo):
        f = open('info.txt','a')
        for each in classinfo:
            #f.writelines('\n\n'+contents+'\n')
            f.writelines('title:'+each['title']+'\n')
            f.writelines('content:'+each['content']+'\n')
            f.writelines('classtime:'+each['classtime']+'\n')
            f.writelines('classlevel:'+each['classlevel']+'\n')
            f.writelines('learnnum:'+each['learnnum']+'\n\n')

        f.close()

if __name__ == '__main__':
    classinfo = []
    url = 'http://www.jikexueyuan.com/course/?pageNum=1'
    jikespider = spider()
    all_links = jikespider.changepage(url,20)

    for link in all_links:
        print u'正在处理页面：'+link
        html = jikespider.getsource(link)
        # i = 0
        # i=i+1
        # ii = str(i)
        # pages = "这个抓的是第"+ii+"页面"
        everyclass = jikespider.geteveryclass(html)
        for each in everyclass:
            info = jikespider.getinfo(each)
            classinfo.append(info)

    jikespider.saveinfo(classinfo)

爬去结果如下