视频抓取原理：获取所有的知识类别id-》然后获取其子项-》根据子项链接分析获取该类课程数-》循环获取链接指向的视频。
需要安装python库：requests
python解析xml使用了网上找的代码。
本来可以再优化。但是懒！
1 # coding: UTF-8
2 import os
3 import sys
4 import requests
5 import urllib.request,io
6 from html.parser import HTMLParser
7
8 #全局变量
9
10 id_list = set() #保存视频ID的列表
11 id_dict = {} #保存id和对应子视频数目
12 cookies = {} #保存cookies
13
14 #HTML解析类
15 class MyHTMLParser(HTMLParser):
16 def __init__(self, key, attr):
17 HTMLParser.__init__(self)
18 self.links = []
19 self.keys = key
20 self.attr = attr
21 def handle_starttag(self, tag, attrs):
22 #print "Encountered the beginning of a %s tag" % tag
23 #if tag == "source":
24 if tag == self.keys:
25 if len(attrs) == 0:
26 pass
27 else:
28 for (variable, value) in attrs:
29 #if variable == "src":
30 if variable == self.attr:
31 self.links.append(value)
32
33
34 #解析cookies字典
35 def getCookies(cookies_str):
36 global cookies
37 for line in cookiesStr.split(';'):
38 #其设置为1就会把字符串拆分成2份
39 name, value = line.strip().split('=', 1)
40 cookies[name] = value
41
42 def getHtml(url, key, value):
43 global cookies
44 r = requests.get(url, cookies=cookies)
45 content = r.content.decode('UTF-8')
46 hp = MyHTMLParser("source", "src")
47 hp.feed(content)
48 hp.close()
49 print(hp.links)
50 for link in hp.links:
51 link_str = str(link)
52 if link_str.find(".mp4") >= 0:
53 downloadFile(link, key, value)
54 else:
55 print("没有找到对应视频")
56
57
58 #获取课程数目
59 def getCourseNum(url):
60 global cookies
61 url_list = set()
62 r = requests.get(url, cookies=cookies)
63 content = r.content.decode('UTF-8')
64 hp = MyHTMLParser("a", "href")
65 hp.feed(content)
66 hp.close()
67 for link in hp.links:
68 link_str = str(link)
69 if link_str.find("http://www.jikexueyuan.com/course/") >= 0 and link_str.find(".html?ss=1") >= 0:
70 url_list.add(link_str)
71 return url_list.__len__()
72
73 #获取所有视频ID，根据目录网页
74 def getIdList(root):
75 global cookies
76 r = requests.get(root, cookies=cookies)
77 content = r.content.decode('UTF-8')
78 hp = MyHTMLParser("a", "href")
79 hp.feed(content)
80 hp.close()
81 #print(hp.links)
82 #声明引用全局id_list,在最上面定义
83 global id_list
84 global id_dict
85
86 for link in hp.links:
87 link_str = str(link)
88 if link_str.find("http://www.jikexueyuan.com/course/") >= 0 and link_str.find(".html")>= 0:
89 #print(link)
90 c_id = link_str.lstrip("http://www.jikexueyuan.com/course/").rstrip(".html")
91 if c_id not in id_list:
92 id_dict[c_id] = getCourseNum(link_str)
93 print(c_id, id_dict[c_id])
94 id_list.add(c_id)
95 print(id_dict)
96
97 def downloadFile(url, key, value):
98 #url = 'http://cv4.jikexueyuan.com/10de45bbf83e450ff5e11ff4599d7166/201603202253/cocos2d-x/course_712/01/video/c712b_01_h264_sd_960_540.mp4'
99 r = requests.get(url)
100 file_name = str(key)+"_"+str(value)+".mp4"
101 with open(file_name, "wb") as code:
102 code.write(r.content)
103
104 if __name__=="__main__":
105 count = 0
106 #解析cookies 利用免费时间下载需要视频，需要账号的cookies
107 cookiesStr = "通过谷歌浏览器可以获取"
108 getCookies(cookiesStr)
109
110
111 root = "http://ke.jikexueyuan.com/xilie/331?huodong=shequn_0307"
112 getIdList(root)
113
114 head = "http://www.jikexueyuan.com/course/"
115
116 for key in id_dict:
117 if id_dict[key] <= 0:
118 print(id_dict[key],"没有数据")
119 break
120 for i in range(1, id_dict[key]+1):
121 url = head+key+"_"+str(i)+".html?ss=1"
122 print("下载:")
123 print(url)
124 count += 1
125 getHtml(url, key, i)
126 print("视频总数：")
127 print(count)
可以优化的点：由于没有获取到每个视频的名字，看起来很不爽。可以获取视频的名字，然后根据类别建立文件夹。这样保存起来更方便观看。
cookies真的可以获取直接用。那么意味着如果截取用户浏览器登陆信息也可以直接登陆并获取有用的信息。哪些黑客获取cookies然后盗取用户信息原理就是这样的么？有意思。
