1）urllib2+BeautifulSoup抓取Goolge搜索链接
近期，参与的项目需要对Google搜索结果进行处理，之前学习了Python处理网页相关的工具。实际应用中，使用了urllib2和beautifulsoup来进行网页的抓取，但是在抓取google搜索结果的时候，发现如果是直接对google搜索结果页面的源代码进行处理，会得到很多“脏”链接。
看下图为搜索“titanic james”的结果：
图中红色标记的是不需要的，蓝色标记的是需要抓取处理的。
这种“脏链接”当然可以通过规则过滤的方法来过滤掉，但是这样程序的复杂度就高了。正当自己愁眉苦脸的正在写过滤规则时。同学提醒说google应该提供相关的api，才恍然大明白。
（2）Google Web Search API+多线程
文档中给出使用Python进行搜索的例子：
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
import
simplejson # The request also includes the userip parameter which provides the end
# user's IP address. Doing so will help distinguish this legitimate
# server-side traffic from traffic which doesn't come from an end-user.
'?v=1.0&q=Paris%20Hilton&userip=USERS-IP-ADDRESS')
request
= urllib2.Request(
url,
None, {'Referer':
/*
Enter the URL of your site here */})
response
= urllib2.urlopen(request)
# Process the JSON string.
results
= simplejson.load(response)
# now have some fun with the results...
import
simplejson # The request also includes the userip parameter which provides the end# user's IP address. Doing so will help distinguish this legitimate# server-side traffic from traffic which doesn't come from an end-user. '?v=1.0&q=Paris%20Hilton&userip=USERS-IP-ADDRESS') request
= urllib2.Request( url,
None, {'Referer':
/*
Enter the URL of your site here */})response
= urllib2.urlopen(request) # Process the JSON string.results
= simplejson.load(response)# now have some fun with the results.. |
实际应用中可能需要抓取google的很多网页，所以还需要使用多线程来分担抓取任务。使用google web search api的参考详细介绍，请看此处（这里介绍了Standard URL Arguments）。另外要特别注意，url中参数rsz必须是8（包括8）以下的值，若大于8，会报错的！
（3）代码实现
代码实现还存在问题，但是能够运行，鲁棒性差，还需要进行改进，希望各路大神指出错误（初学Python），不胜感激。
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
|
#-*-coding:utf-8-*-
import
urllib2,urllib import
simplejson import
os, time,threading import
common, html_filter #input the keywords
keywords
= raw_input('Enter the keywords: ')
#define rnum_perpage, pages
rnum_perpage=8pages=8 #定义线程函数
def
thread_scratch(url, rnum_perpage, page): url_set
= []
try:
response
= urllib2.urlopen(request)
# Process the JSON string.
results
= simplejson.load(response)
info
= results['responseData']['results']
except
Exception,e: print
'error occured' print
e else:
for
minfo in
info: url_set.append(minfo['url'])
print
minfo['url']
#处理链接
i
= 0 for
u in
url_set: try:
request_url.add_header(
'User-agent',
'CSC' )
response_data
= urllib2.urlopen(request_url).read()
#过滤文件
#content_data = html_filter.filter_tags(response_data)
#写入文件
filenum
= i+page
filename
= dir_name+'/related_html_'+str(filenum)
print
' write start: related_html_'+str(filenum)
f
= open(filename,
'w+',
-1)
f.write(response_data)
#print content_data
f.close()
print
' write down: related_html_'+str(filenum)
except
Exception, e: print
'error occured 2' print
e i
= i+1 return #创建文件夹
dir_name
= 'related_html_'+urllib.quote(keywords)
if
os.path.exists(dir_name): print
'exists file' common.delete_dir_or_file(dir_name)
os.makedirs(dir_name)
#抓取网页
print
'start to scratch web pages:'for
x in
range(pages): print
"page:%s"%(x+1)
page
= x
* rnum_perpage
'?v=1.0&q=%s&rsz=%s&start=%s')
% (urllib.quote(keywords), rnum_perpage,page)
print
url t
= threading.Thread(target=thread_scratch, args=(url,rnum_perpage,
page)) t.start()
#主线程等待子线程抓取完
main_thread
= threading.currentThread()
for
t in
threading.enumerate():
if
t is
main_thread: continue t.join() |
