urllib.error

#捕获异常
import urllib.request
import urllib.error

try:
    response = urllib.request.urlopen('http://sasd.com')
except urllib.error.URLError as e:
    print('挂掉的情形是：',e.reason)

import urllib.request
import urllib.error
try:
    response = urllib.request.urlopen('http://www.asdddwf.com')
except urllib.error.HTTPError as e:
    print(e.reason,e.code,e.headers,sep='
')
except urllib.error.URLError as e:
    print(e.reason)
else:
    print('Requset Successfully')
#urllib.error的异常分类
#URlError，下面有个reason
#URLError的子类是HTTPError，下面有code,reason,headers
#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

#验证异常的具体原因
import socket
import urllib.request
import urllib.error

try:
    response = urllib.request.urlopen('http://www.baidu.com',timeout=0.01)
except urllib.error.URLError as e:
    print(e.reason)
    if isinstance(e.reason,socket.timeout):
        print('TIME OUT!')