关于python官网urllib2实例的问题

python官网Docs有介绍urllib2，里面有实例，对于python2.7版本，页面是： https://docs.python.org/2/howto/urllib2.html 在“Wrapping it Up”这一节，有number1和number2两个例子，其中第二个例子有些问题： if拦截了URLError，后面的elif永远不会执行，因为e永远有reason值，如果是普通URLError，reason就是给出的描述，如果是HTTPError（属于URLError里面一个子集），那么print出来是“OK”，所以如果是有URLError，hasattr(e, 'reason')总是成立，轮不到后面的elif部分执行；应该像前面的number1一样调整下顺序，先处理HTTPError再考虑URLError。 附： 下面是原文档： Wrapping it Up So if you want to be prepared for HTTPError or URLError there are two basic approaches. I prefer the second approach. Number 1 from urllib2 import Request, urlopen, URLError, HTTPError req = Request(someurl) try: response = urlopen(req) except HTTPError as e: print 'The server couldn\'t fulfill the request.' print 'Error code: ', e.code except URLError as e: print 'We failed to reach a server.' print 'Reason: ', e.reason else: # everything is fine Note The except HTTPError must come first, otherwise except URLError will also catch an HTTPError. Number 2 from urllib2 import Request, urlopen, URLError req = Request(someurl) try: response = urlopen(req) except URLError as e: if hasattr(e, 'reason'): print 'We failed to reach a server.' print 'Reason: ', e.reason elif hasattr(e, 'code'): print 'The server couldn\'t fulfill the request.' print 'Error code: ', e.code else: # everything is fine