<Python高级编程技巧实战>课程售出提醒程序

1. 每分钟抓取一次课程页面学习人数.
2. 和前次进行对比, 数量增加意味课程卖出, 播放本地音乐.
3. 同时监听多们课程.

from threading import Timer
from scrapy.selector import Selector
from subprocess import getoutput
import requests

COURSES = {
 # Python高级编程技巧实战
 62: {
     'url': 'http://coding.imooc.com/class/62.html',
     'mp3': 'happy.mp3',
 },

 75: {
     'url': 'http://coding.imooc.com/class/75.html',
     'mp3': 'happy2.mp3',
 },

 74: {
     'url': 'http://coding.imooc.com/class/74.html',
     'mp3': 'happy3.mp3',
 },
}

def getSalesVolume(courses):
    res = {}
    for course in courses:
 url = COURSES[course]['url']
 response = requests.get(url)
 sel = Selector(text=response.text)

 sv = sel.css('div.static-item:nth-child(3) > 
  span.meta-value > strong::text').extract_first()
 res[course] = int(sv)
    return res

def loop(courses, svOld):
    try:
 sv = getSalesVolume(courses)
 for course in courses:
     print(course, svOld[course], sv[course])
     cmd = 'play %s' % COURSES[course]['mp3']
     for _ in range(sv[course] - svOld[course]):
  getoutput(cmd)
 svOld = sv
    except IOError as e:
 print(e)

    Timer(60, loop, args=(courses, svOld)).start()

courses = [62, 75, 74]
loop(courses, getSalesVolume(courses))