python抓取百度搜索结果

# -*- coding: utf-8 -*-
#!/usr/bin/env python
#抓取百度搜索结果
import sys
import re 
import urllib2

from BeautifulSoup import BeautifulSoup

def search(key):
        search_url='http://www.baidu.com/s?wd=key&rsv_bp=0&rsv_spt=3&rsv_n=2&inputT=6391' 
        req=urllib2.urlopen(search_url.replace('key',key)) 
        result=[]  
        #循环抓取10页结果进行解析
        for count in range(10):
                html=req.read()
                soup=BeautifulSoup(html)
    
                file = open("result.txt",'a')
                
                content  = soup.findAll('table',id=re.compile("\d"))
                num = len(content)
                
                for i in range(num):
                    #先解析出来内容
                    p_str  = content[i].find('a')
                    #提取关键字
                    if p_str.em:
                        str = "".join(p_str.em.string)
                    #提取缩略标题
                    patt = re.compile(u"<\/em>(.*?)<\/a>")
                    text = re.search(patt,unicode(p_str))
                    if text:
                        str +=  text.group(1)
                    #构造字典序列
                    #result +=[{str:p_str['href']}]
                    file.write(str+u'\n'+unicode(p_str['href'])+u'\n')
                    
                file.close()
                #解析下一页
                next_page='http://www.baidu.com'+soup('a',{'href':True,'class':'n'})[0]['href'] # search for the next page
                req=urllib2.urlopen(next_page)
      
if __name__=='__main__':
        key=raw_input('input key word:')
        search(key)