python BeautifulSoup 获取页面多个子节点中的各个节点的内容

页面html格式为

<tr bgcolor="#7bb5de">
<td style="border-bottom: 1px solid #C9D8AD" width="118" align="center" bgcolor="#D9E6FF">
<p align="center">
lyl5577d92</p></td>
<td style="border-bottom: 1px solid #C9D8AD" width="96" align="center" bgcolor="#D9E6FF">
<p align="center">李永利</p></td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="105" bgcolor="#D9E6FF">
<div align="center"><font color="#FF0000">lyl5577d</font></div>
</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="153" bgcolor="#D9E6FF">
<div align="center">469680008</div>
</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="218" bgcolor="#D9E6FF">
<div align="center">2016-05-21 15:24:27.0</div>
</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="171" bgcolor="#D9E6FF">
<div align="center">0</div>
</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="119" bgcolor="#D9E6FF">0</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="111" bgcolor="#D9E6FF">0</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="87" bgcolor="#D9E6FF">0</td>
<td align="center" style="border-bottom: 1px solid #C9D8AD" width="128" bgcolor="#D9E6FF">0</td>
</tr>

 import httplib
 from BeautifulSoup import BeautifulSoup

 def main():
     f = open('result','a')

     headers = {'Content-Type':'application/x-www-form-urlencoded',
         'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8',
         'Accept-Language': 'zh-CN,zh;q=0.8,en-US;q=0.5,en;q=0.3',
         'Accept-Encoding': 'gzip, deflate',
         'Referer': 'http://xxx.xxx.com/admin/userlist',
         'Cookie': 'JSESSIONID=9F6F2D03D2C11400B3D6731E90D73117',
         'User-Agent': 'User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:46.0) Gecko/20100101 Firefox/46.0',
     }

     conn = httplib.HTTPConnection('*.*.*.*', timeout=50)

     for p in range(1,1287):
         print p
         conn.request(method='GET',
                         url="/admin/userlist?toPage=%s&sessionID=" % str(p),
                         headers=headers)
         resp = conn.getresponse()
         html_doc = resp.read()
         mainSoup = BeautifulSoup(html_doc)
         for s in mainSoup.findAll('tr', attrs={'bgcolor':'#7bb5de'}):
             if 'style' not in str(s):
                 continue
             for d in s.findAll('td'):
                 print d.getText(),
                 f.write("%s " % d.getText().encode('utf-8'))   #f.write("%s " % d.getText())==> UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-2: ordinal not in range(128)
             f.write("%s\n" % d.getText().encode('utf-8'))
             print
     f.close()
     conn.close()

 if __name__ == '__main__':
     main()