python爬虫爬取监控教务系统的思路详解

import datetime
import time
from email.header import Header
import requests
import re
import smtplib
from email.mime.text import MIMEText
from bs4 import BeautifulSoup
def listener():
 #在这里我通过模拟登陆的方式登陆
 #一般来说这里填写的是username跟password
 #但我们学校后台将用户名和密码进行了加密
 #通过观察浏览器的请求数据跟页面源码猜出学校后台的加密方式
 data={
 #出于学校安全考虑，这里就不给出加密方式了
 'encoded':'xxxxxxxxxxxxxxxxxxx'
 }
 session = requests.Session()
 session.post('http://jwc.sgu.edu.cn/jsxsd/xk/LoginToXk',data=data)
 #请求2019-2020-1学期的所有成绩
 r_data = {
 'kksj': '2019-2020-1',
 'kcxz': '',
 'kcmc': '',
 'xsfs': 'all'
 }
 r = session.post('http://jwc.sgu.edu.cn/jsxsd/kscj/cjcx_list', data=r_data)
 #对爬回来数据进行封装
 soup = BeautifulSoup(r.text, 'html.parser')
 #返回已有的成绩列表
 oldList = toList(soup)
 max = len(oldList)
 #这里用死循环定时爬取成绩页面分析是否分布新成绩
 while (True):
 #post跟get方式不能乱用，不然数据会出错
 r = session.post('http://jwc.sgu.edu.cn/jsxsd/kscj/cjcx_list',data=r_data)
 soup = BeautifulSoup(r.text, 'lxml')
 #print(soup.prettify())
 length = len(soup.find_all(string=re.compile('2019-2020-1')))-1
 print("course_length: ",length)
 if (r.status_code == 200 and length != 0):
  if (length > max):
  #查询新出的成绩列表
  newlist = toList(soup)
  #获取两个列表不同之处，不同的就是新成绩
  diflist = compareTwoList(oldList, newlist)
  oldList=newlist
  if diflist=='':
   send("unkowned Error","unkowned Error")
  else:
   #有新成绩了，发送邮件通知我
   send('you have new course sorce!!', diflist)
  max = length
  print('last running time was:',datetime.datetime.now())
  #定时作用，500s查一次
  time.sleep(500)
 else:
  # 发送邮件断开连接了 print("had disconnected...")
  send("your server is disconnected!!!","your server is disconnected!!!")
  break
def send(title,msg):
 mail_host = 'smtp.qq.com'
 # 你的qq邮箱名，没有.com
 mail_user = '你的qq邮箱名，没有.com'
 # 密码(部分邮箱为授权码)
 mail_pass = '授权码'
 # 邮件发送方邮箱地址
 sender = '发送方邮箱地址'
 # 邮件接受方邮箱地址，注意需要[]包裹，这意味着你可以写多个邮件地址群发
 receivers = ['yoletpig@qq.com']
 # 设置email信息
 # 邮件内容设置
 message = MIMEText(msg, 'plain', 'utf-8')
 # 邮件主题
 message['Subject'] = Header(title,'utf-8')
 # 发送方信息
 message['From'] = sender
 # 接受方信息
 message['To'] = receivers[0]
 # 登录并发送邮件
 try:
 # smtpObj = smtplib.SMTP()
 # # 连接到服务器
 # smtpObj.connect(mail_host, 25)
 smtpObj = smtplib.SMTP_SSL(mail_host)
 # 登录到服务器
 smtpObj.login(mail_user, mail_pass)
 # 发送
 smtpObj.sendmail(
  sender,receivers,message.as_string())
 # 退出
 smtpObj.quit()
 print('success')
 except smtplib.SMTPException as e:
 print('error', e) # 打印错误
def toList(soup):
 flag = True
 list = []
 strs = ''
 #对tr标签下的td进行遍历并取值
 for tr in soup.find_all('tr'):
 if flag:
  flag = False;
  continue
 i = 1
 for td in tr.stripped_strings:
  if (i == 1 or i == 2):
  i += 1
  continue
  strs += "_" + td
  i += 1
 list.append(strs)
 strs = ''
 return list
def compareTwoList(oldList,newList):
 diflist=''
 for sub in newList:
 #判断是否唯一
 if(oldList.count(sub)==0):
  diflist = sub
  break
 return diflist
if __name__ == '__main__':
 listener()