在使用 Pythonrequests模块检查断开的链接(预期行为是返回不可用 URL 的错误代码，例如 404 等(时，我在页面上遇到了一个不再存在的域的旧链接，并返回了 DNS 错误。
<snip>
http://listen.grooveshark.com/s/Folk+Song/2Np5i?src=5
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/urllib3/connection.py", line 171, in _new_conn
(self._dns_host, self.port), self.timeout, **extra_kw)
File "/usr/local/lib/python3.7/site-packages/urllib3/util/connection.py", line 56, in create_connection
for res in socket.getaddrinfo(host, port, family, socket.SOCK_STREAM):
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/socket.py", line 748, in getaddrinfo
for res in _socket.getaddrinfo(host, port, family, type, proto, flags):
socket.gaierror: [Errno 8] nodename nor servname provided, or not known
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 600, in urlopen
chunked=chunked)
File "/usr/local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 354, in _make_request
conn.request(method, url, **httplib_request_kw)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 1229, in request
self._send_request(method, url, body, headers, encode_chunked)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 1275, in _send_request
self.endheaders(body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 1224, in endheaders
self._send_output(message_body, encode_chunked=encode_chunked)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 1016, in _send_output
self.send(msg)
File "/usr/local/Cellar/python/3.7.0/Frameworks/Python.framework/Versions/3.7/lib/python3.7/http/client.py", line 956, in send
self.connect()
File "/usr/local/lib/python3.7/site-packages/urllib3/connection.py", line 196, in connect
conn = self._new_conn()
File "/usr/local/lib/python3.7/site-packages/urllib3/connection.py", line 180, in _new_conn
self, "Failed to establish a new connection: %s" % e)
urllib3.exceptions.NewConnectionError: <urllib3.connection.HTTPConnection object at 0x1088ff748>: Failed to establish a new connection: [Errno 8] nodename nor servname provided, or not known
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/usr/local/lib/python3.7/site-packages/requests/adapters.py", line 445, in send
timeout=timeout
File "/usr/local/lib/python3.7/site-packages/urllib3/connectionpool.py", line 638, in urlopen
_stacktrace=sys.exc_info()[2])
File "/usr/local/lib/python3.7/site-packages/urllib3/util/retry.py", line 398, in increment
raise MaxRetryError(_pool, url, error or ResponseError(cause))
urllib3.exceptions.MaxRetryError: HTTPConnectionPool(host='listen.grooveshark.com', port=80): Max retries exceeded with url: /s/Folk+Song/2Np5i?src=5 (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x1088ff748>: Failed to establish a new connection: [Errno 8] nodename nor servname provided, or not known'))
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "./four_finder.py", line 64, in <module>
do_main()
File "./four_finder.py", line 48, in do_main
resp = requests.get(link)
File "/usr/local/lib/python3.7/site-packages/requests/api.py", line 72, in get
return request('get', url, params=params, **kwargs)
File "/usr/local/lib/python3.7/site-packages/requests/api.py", line 58, in request
return session.request(method=method, url=url, **kwargs)
File "/usr/local/lib/python3.7/site-packages/requests/sessions.py", line 512, in request
resp = self.send(prep, **send_kwargs)
File "/usr/local/lib/python3.7/site-packages/requests/sessions.py", line 622, in send
r = adapter.send(request, **kwargs)
File "/usr/local/lib/python3.7/site-packages/requests/adapters.py", line 513, in send
raise ConnectionError(e, request=request)
requests.exceptions.ConnectionError: HTTPConnectionPool(host='listen.grooveshark.com', port=80): Max retries exceeded with url: /s/Folk+Song/2Np5i?src=5 (Caused by NewConnectionError('<urllib3.connection.HTTPConnection object at 0x1088ff748>: Failed to establish a new connection: [Errno 8] nodename nor servname provided, or not known'))
[user@host:~/dev|22:13:13]
$ nslookup listen.grooveshark.com
(...)
** server can't find listen.grooveshark.com: SERVFAIL
[user@host:~/dev|22:28:05]
防止此错误发生的最佳方法是什么？我对未来的输入 URL 没有信心(因为此示例不存在(。
这是通过使用 try/except 块和请求来解决的。连接错误。我没有在SE中搜索正确的术语，这里有一个有用的答案。
try:
resp = requests.get(link)
except requests.ConnectionError as e:
### TODO: Properly handle this DNS error!
print('DNS ERROR: %s' % link)
continue
同样令人感兴趣的是这个答案。