1 #捕获异常
2 import urllib.request
3 import urllib.error
4 
5 try:
6     response = urllib.request.urlopen(‘http://sasd.com‘)
7 except urllib.error.URLError as e:
8     print(‘挂掉的情形是：‘,e.reason)

 1 import urllib.request
 2 import urllib.error
 3 try:
 4     response = urllib.request.urlopen(‘http://www.asdddwf.com‘)
 5 except urllib.error.HTTPError as e:
 6     print(e.reason,e.code,e.headers,sep=‘\n‘)
 7 except urllib.error.URLError as e:
 8     print(e.reason)
 9 else:
10     print(‘Requset Successfully‘)
11 #urllib.error的异常分类
12 #URlError，下面有个reason
13 #URLError的子类是HTTPError，下面有code,reason,headers
14 #捕捉异常要把子类开始捕捉，因为一旦捕捉第一个，后面的异常判断就不会继续执行了

 1 #验证异常的具体原因
 2 import socket
 3 import urllib.request
 4 import urllib.error
 5 
 6 try:
 7     response = urllib.request.urlopen(‘http://www.baidu.com‘,timeout=0.01)
 8 except urllib.error.URLError as e:
 9     print(e.reason)
10     if isinstance(e.reason,socket.timeout):
11         print(‘TIME OUT!‘)