大多数APP里面返回的是json格式数据，或者一堆加密过的数据 。这里以超级课程表APP为例，抓取超级课程表里用户发的话题。
1、抓取APP数据包
方法详细可以参考这篇博文：Fiddler如何抓取手机APP数据包
得到超级课程表登录的地址：http://120.55.151.61/V2/StudentSkip/loginCheckV4.action
表单：
表单中包括了用户名和密码，当然都是加密过了的，还有一个设备信息，直接post过去就是。
另外必须加header,一开始我没有加header得到的是登录错误，所以要带上header信息。
2、登录
登录代码：
import urllib2from cookielib import CookieJarloginUrl = 'http://120.55.151.61/V2/StudentSkip/loginCheckV4.action'headers = {'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8','User-Agent': 'Dalvik/1.6.0 (Linux; U; Android 4.1.1; M040 Build/JRO03H)','Host': '120.55.151.61','Connection': 'Keep-Alive','Accept-Encoding': 'gzip','Content-Length': '207',}loginData = 'phoneBrand=Meizu&platform=1&deviceCode=868033014919494&account=FCF030E1F2F6341C1C93BE5BBC422A3D&phoneVersion=16&password=A55B48BB75C79200379D82A18C5F47D6&channel=MXMarket&phoneModel=M040&versionNumber=7.2.1&'cookieJar = CookieJar()opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cookieJar))req = urllib2.Request(loginUrl, loginData, headers)loginResult = opener.open(req).read()print loginResult 登录成功 会返回一串账号信息的json数据
和抓包时返回数据一样，证明登录成功
3、抓取数据
用同样方法得到话题的url和post参数
做法就和模拟登录网站一样。详见：Python爬虫模拟登录带验证码网站
下见最终代码，有主页获取和下拉加载更新。可以无限加载话题内容。
#!/usr/local/bin/python2.7# -*- coding: utf8 -*-"""超级课程表话题抓取"""import urllib2from cookielib import CookieJarimport json''' 读Json数据 '''def fetch_data(json_data):data = json_data['data']timestampLong = data['timestampLong']messageBO = data['messageBOs']topicList = []for each in messageBO:topicDict = {}if each.get('content', False):topicDict['content'] = each['content']topicDict['schoolName'] = each['schoolName']topicDict['messageId'] = each['messageId']topicDict['gender'] = each['studentBO']['gender']topicDict['time'] = each['issueTime']print each['schoolName'],each['content']topicList.append(topicDict)return timestampLong, topicList''' 加载更多 '''def load(timestamp, headers, url):headers['Content-Length'] = '159'loadData = 'timestamp=%s&phoneBrand=Meizu&platform=1&genderType=-1&topicId=19&phoneVersion=16&selectType=3&channel=MXMarket&phoneModel=M040&versionNumber=7.2.1&' % timestampreq = urllib2.Request(url, loadData, headers)loadResult = opener.open(req).read()loginStatus = json.loads(loadResult).get('status', False)if loginStatus == 1:print 'load successful!'timestamp, topicList = fetch_data(json.loads(loadResult))load(timestamp, headers, url)else:print 'load fail'print loadResultreturn FalseloginUrl = 'http://120.55.151.61/V2/StudentSkip/loginCheckV4.action'topicUrl = 'http://120.55.151.61/V2/Treehole/Message/getMessageByTopicIdV3.action'headers = {'Content-Type': 'application/x-www-form-urlencoded; charset=UTF-8','User-Agent': 'Dalvik/1.6.0 (Linux; U; Android 4.1.1; M040 Build/JRO03H)','Host': '120.55.151.61','Connection': 'Keep-Alive','Accept-Encoding': 'gzip','Content-Length': '207',}''' ---登录部分--- '''loginData = 'phoneBrand=Meizu&platform=1&deviceCode=868033014919494&account=FCF030E1F2F6341C1C93BE5BBC422A3D&phoneVersion=16&password=A55B48BB75C79200379D82A18C5F47D6&channel=MXMarket&phoneModel=M040&versionNumber=7.2.1&'cookieJar = CookieJar()opener = urllib2.build_opener(urllib2.HTTPCookieProcessor(cookieJar))req = urllib2.Request(loginUrl, loginData, headers)loginResult = opener.open(req).read()loginStatus = json.loads(loginResult).get('data', False)if loginResult:print 'login successful!'else:print 'login fail'print loginResult''' ---获取话题--- '''topicData = 'timestamp=0&phoneBrand=Meizu&platform=1&genderType=-1&topicId=19&phoneVersion=16&selectType=3&channel=MXMarket&phoneModel=M040&versionNumber=7.2.1&'headers['Content-Length'] = '147'topicRequest = urllib2.Request(topicUrl, topicData, headers)topicHtml = opener.open(topicRequest).read()topicJson = json.loads(topicHtml)topicStatus = topicJson.get('status', False)print topicJsonif topicStatus == 1:print 'fetch topic success!'timestamp, topicList = fetch_data(topicJson)load(timestamp, headers, topicUrl) 结果：
