any

from urllib2 import Request, urlopen, URLError, HTTPError  
req = Request(‘http://bbs.csdn.net/callmewhy‘)  
  
try:  
    response = urlopen(req)  
except HTTPError, e:  
    print ‘The server couldn\‘t fulfill the request.‘  
    print ‘Error code: ‘, e.code    #HttpError是URLError的子类，
except URLError, e:  
    print ‘We failed to reach a server.‘  
    print ‘Reason: ‘, e.reason  
else:  
    print ‘No exception was raised.‘