Python多线程抓取Google搜索链接网页[python高级教程]

Python多线程抓取Google搜索链接网页[python高级教程]

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:

QQ截图20130407145449

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:

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.

url = ("https://ajax.googleapis.com/ajax/services/search/web"

"?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.

url = ("https://ajax.googleapis.com/ajax/services/search/web"

"?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。

python;toolbar:false;">#-*-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=8

pages=8

#定义线程函数

def thread_scratch(url, rnum_perpage, page):

url_set = []

try:

request = urllib2.Request(url, None, {"Referer": "http://www.sina.com"})

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 = urllib2.Request(u, None, {"Referer": "http://www.sina.com"})

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

url = ("https://ajax.googleapis.com/ajax/services/search/web"

"?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()


以上是 Python多线程抓取Google搜索链接网页[python高级教程] 的全部内容, 来源链接: utcz.com/z/540140.html

回到顶部