如何捕获多个异常？

Question

我通常很擅长捕捉异常，但这个组让我感到困惑。这是我正在使用的代码（它使用 pywinrm）：

import socket
def win_Upgrade_Check(kbByOS):
    for os in kbByOS:
        print(os)
        try:
            conn = winrm.Session(os, auth=("administrator","****"))
            for kb in kbByOS[os]:
                resp = conn.run_ps("get-hotfix -id {0}".format(kb))
                output = resp.std_out.decode('utf-8')
                error = resp.std_err
                if error:
                    print("KB{} not found on {}.".format(error,os))
                else:
                    print("{} found on {}.".format(kb,os))
        except timeout as e:
            print(e)
            pass

这是我收到的当前错误的吐词：

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connection.py", line 142, in _new_conn
(self.host, self.port), self.timeout, **extra_kw)
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
socket.timeout: timed out

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connection.py", line 142, in _new_conn
(self.host, self.port), self.timeout, **extra_kw)
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/util/connection.py", line 91, in create_connection
    raise err
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/util/connection.py", line 81, in create_connection
    sock.connect(sa)
socket.timeout: timed out

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connectionpool.py", line 578, in urlopen
    chunked=chunked)
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connectionpool.py", line 362, in _make_request
    conn.request(method, url, **httplib_request_kw)
  File "/usr/lib/python3.5/http/client.py", line 1106, in request
    self._send_request(method, url, body, headers)
  File "/usr/lib/python3.5/http/client.py", line 1151, in _send_request
    self.endheaders(body)
  File "/usr/lib/python3.5/http/client.py", line 1102, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python3.5/http/client.py", line 934, in _send_output
    self.send(msg)
  File "/usr/lib/python3.5/http/client.py", line 877, in send
    self.connect()
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connection.py", line 167, in connect
    conn = self._new_conn()
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connection.py", line 147, in _new_conn
    (self.host, self.timeout))
requests.packages.urllib3.exceptions.ConnectTimeoutError: (<requests.packages.urllib3.connection.HTTPConnection object at 0x7fc019afed30>, 'Connection to **** timed out. (connect timeout=30)')

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/local/lib/python3.5/dist-packages/requests/adapters.py", line 403, in send
    timeout=timeout
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/connectionpool.py", line 623, in urlopen
    _stacktrace=sys.exc_info()[2])
  File "/usr/local/lib/python3.5/dist-packages/requests/packages/urllib3/util/retry.py", line 281, in increment
    raise MaxRetryError(_pool, url, error or ResponseError(cause))
requests.packages.urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='****', port=5985): Max retries exceeded with url: /wsman (Caused by ConnectTimeoutError(<requests.packages.urllib3.connection.HTTPConnection object at 0x7fc019afed30>, 'Connection to **** timed out. (connect timeout=30)'))

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "bulletin_parse.py", line 258, in <module>
    win_Upgrade_Check(kbByOS)
  File "bulletin_parse.py", line 247, in win_Upgrade_Check
    resp = conn.run_ps("get-hotfix -id {0}".format(kb))
  File "/usr/local/lib/python3.5/dist-packages/winrm/__init__.py", line 54, in run_ps
    rs = self.run_cmd('powershell -encodedcommand {0}'.format(encoded_ps))
  File "/usr/local/lib/python3.5/dist-packages/winrm/__init__.py", line 41, in run_cmd
    shell_id = self.protocol.open_shell()
  File "/usr/local/lib/python3.5/dist-packages/winrm/protocol.py", line 132, in open_shell
    res = self.send_message(xmltodict.unparse(req))
  File "/usr/local/lib/python3.5/dist-packages/winrm/protocol.py", line 207, in send_message
    return self.transport.send_message(message)
  File "/usr/local/lib/python3.5/dist-packages/winrm/transport.py", line 173, in send_message
    response = self.session.send(prepared_request, timeout=self.read_timeout_sec)
  File "/usr/local/lib/python3.5/dist-packages/requests/sessions.py", line 585, in send
    r = adapter.send(request, **kwargs)
  File "/usr/local/lib/python3.5/dist-packages/requests/adapters.py", line 459, in send
    raise ConnectTimeout(e, request=request)
requests.exceptions.ConnectTimeout: HTTPConnectionPool(host='****', port=5985): Max retries exceeded with url: /wsman (Caused by ConnectTimeoutError(<requests.packages.urllib3.connection.HTTPConnection object at 0x7fc019afed30>, 'Connection to **** timed out. (connect timeout=30)'))

正如您在我当前的代码中看到的，我首先尝试捕获 socket.timeout 。我还尝试将其更改为 except Exception as e，认为 catch all 甚至会比我目前拥有的更好，但这也失败了。我尝试编辑 Transport.py 为 requests.exceptions.ConnectTimeout 添加异常，但这也没有捕获它。

由于发生了多个异常，是否需要做一些特殊的事情？

Answer 1

您可以根据需要添加任意多个不同的例外：

try:
    doMyFavoriteThing()
except ValueError:
    print "Whoops!"
except timeout:
    print "Whoopsies!"
except MaxRetryError:
    print "Whoopsie daisies!"

或者如果你想捕获所有异常，因为所有异常都是该类的子类Exception，你可以这样做：

try:
    doMyFavoriteThing()
except Exception as e:
    print str(e)

当然，通常认为第一种方法更好 - 您可能会用其他格式捕获 NameErrors 或其他愚蠢的错误。