20.10. http.client — HTTP protocol client

This module defines classes which implement the client side of the HTTP and HTTPS protocols. It is normally not used directly — the module urllib.request uses it to handle URLs that use HTTP and HTTPS.

注解

HTTPS support is only available if the socket module was compiled with SSL support.

The module provides the following classes:

class http.client.HTTPConnection(host, port=None, strict=None[, timeout])

An HTTPConnection instance represents one transaction with an HTTP server. It should be instantiated passing it a host and optional port number. If no port number is passed, the port is extracted from the host string if it has the form host:port, else the default HTTP port (80) is used. When True, the optional parameter strict (which defaults to a false value) causes BadStatusLine to be raised if the status line can’t be parsed as a valid HTTP/1.0 or 1.1 status line. If the optional timeout parameter is given, blocking operations (like connection attempts) will timeout after that many seconds (if it is not given, the global default timeout setting is used).

For example, the following calls all create instances that connect to the server at the same host and port:

>>> h1 = http.client.HTTPConnection('www.cwi.nl')
>>> h2 = http.client.HTTPConnection('www.cwi.nl:80')
>>> h3 = http.client.HTTPConnection('www.cwi.nl', 80)
>>> h3 = http.client.HTTPConnection('www.cwi.nl', 80, timeout=10)

class http.client.HTTPSConnection(host, port=None, key_file=None, cert_file=None, strict=None[, timeout])

A subclass of HTTPConnection that uses SSL for communication with secure servers. Default port is 443. key_file is the name of a PEM formatted file that contains your private key, and cert_file is a PEM formatted certificate chain file; both can be used for authenticating yourself against the server.

警告

This does not do any verification of the server’s certificate.

class http.client.HTTPResponse(sock, debuglevel=0, strict=0, method=None, url=None)

Class whose instances are returned upon successful connection. Not instantiated directly by user.

The following exceptions are raised as appropriate:

exception http.client.HTTPException

The base class of the other exceptions in this module. It is a subclass of Exception.

exception http.client.NotConnected

A subclass of HTTPException.

exception http.client.InvalidURL

A subclass of HTTPException, raised if a port is given and is either non-numeric or empty.

exception http.client.UnknownProtocol

A subclass of HTTPException.

exception http.client.UnknownTransferEncoding

A subclass of HTTPException.

exception http.client.UnimplementedFileMode

A subclass of HTTPException.

exception http.client.IncompleteRead

A subclass of HTTPException.

exception http.client.ImproperConnectionState

A subclass of HTTPException.

exception http.client.CannotSendRequest

A subclass of ImproperConnectionState.

exception http.client.CannotSendHeader

A subclass of ImproperConnectionState.

exception http.client.ResponseNotReady

A subclass of ImproperConnectionState.

exception http.client.BadStatusLine

A subclass of HTTPException. Raised if a server responds with a HTTP status code that we don’t understand.

The constants defined in this module are:

http.client.HTTP_PORT

The default port for the HTTP protocol (always 80).

http.client.HTTPS_PORT

The default port for the HTTPS protocol (always 443).

and also the following constants for integer status codes:

Constant	Value	Definition
CONTINUE	100	HTTP/1.1, RFC 2616, Section 10.1.1
SWITCHING_PROTOCOLS	101	HTTP/1.1, RFC 2616, Section 10.1.2
PROCESSING	102	WEBDAV, RFC 2518, Section 10.1
OK	200	HTTP/1.1, RFC 2616, Section 10.2.1
CREATED	201	HTTP/1.1, RFC 2616, Section 10.2.2
ACCEPTED	202	HTTP/1.1, RFC 2616, Section 10.2.3
NON_AUTHORITATIVE_INFORMATION	203	HTTP/1.1, RFC 2616, Section 10.2.4
NO_CONTENT	204	HTTP/1.1, RFC 2616, Section 10.2.5
RESET_CONTENT	205	HTTP/1.1, RFC 2616, Section 10.2.6
PARTIAL_CONTENT	206	HTTP/1.1, RFC 2616, Section 10.2.7
MULTI_STATUS	207	WEBDAV RFC 2518, Section 10.2
IM_USED	226	Delta encoding in HTTP, RFC 3229, Section 10.4.1
MULTIPLE_CHOICES	300	HTTP/1.1, RFC 2616, Section 10.3.1
MOVED_PERMANENTLY	301	HTTP/1.1, RFC 2616, Section 10.3.2
FOUND	302	HTTP/1.1, RFC 2616, Section 10.3.3
SEE_OTHER	303	HTTP/1.1, RFC 2616, Section 10.3.4
NOT_MODIFIED	304	HTTP/1.1, RFC 2616, Section 10.3.5
USE_PROXY	305	HTTP/1.1, RFC 2616, Section 10.3.6
TEMPORARY_REDIRECT	307	HTTP/1.1, RFC 2616, Section 10.3.8
BAD_REQUEST	400	HTTP/1.1, RFC 2616, Section 10.4.1
UNAUTHORIZED	401	HTTP/1.1, RFC 2616, Section 10.4.2
PAYMENT_REQUIRED	402	HTTP/1.1, RFC 2616, Section 10.4.3
FORBIDDEN	403	HTTP/1.1, RFC 2616, Section 10.4.4
NOT_FOUND	404	HTTP/1.1, RFC 2616, Section 10.4.5
METHOD_NOT_ALLOWED	405	HTTP/1.1, RFC 2616, Section 10.4.6
NOT_ACCEPTABLE	406	HTTP/1.1, RFC 2616, Section 10.4.7
PROXY_AUTHENTICATION_REQUIRED	407	HTTP/1.1, RFC 2616, Section 10.4.8
REQUEST_TIMEOUT	408	HTTP/1.1, RFC 2616, Section 10.4.9
CONFLICT	409	HTTP/1.1, RFC 2616, Section 10.4.10
GONE	410	HTTP/1.1, RFC 2616, Section 10.4.11
LENGTH_REQUIRED	411	HTTP/1.1, RFC 2616, Section 10.4.12
PRECONDITION_FAILED	412	HTTP/1.1, RFC 2616, Section 10.4.13
REQUEST_ENTITY_TOO_LARGE	413	HTTP/1.1, RFC 2616, Section 10.4.14
REQUEST_URI_TOO_LONG	414	HTTP/1.1, RFC 2616, Section 10.4.15
UNSUPPORTED_MEDIA_TYPE	415	HTTP/1.1, RFC 2616, Section 10.4.16
REQUESTED_RANGE_NOT_SATISFIABLE	416	HTTP/1.1, RFC 2616, Section 10.4.17
EXPECTATION_FAILED	417	HTTP/1.1, RFC 2616, Section 10.4.18
UNPROCESSABLE_ENTITY	422	WEBDAV, RFC 2518, Section 10.3
LOCKED	423	WEBDAV RFC 2518, Section 10.4
FAILED_DEPENDENCY	424	WEBDAV, RFC 2518, Section 10.5
UPGRADE_REQUIRED	426	HTTP Upgrade to TLS, RFC 2817, Section 6
INTERNAL_SERVER_ERROR	500	HTTP/1.1, RFC 2616, Section 10.5.1
NOT_IMPLEMENTED	501	HTTP/1.1, RFC 2616, Section 10.5.2
BAD_GATEWAY	502	HTTP/1.1 RFC 2616, Section 10.5.3
SERVICE_UNAVAILABLE	503	HTTP/1.1, RFC 2616, Section 10.5.4
GATEWAY_TIMEOUT	504	HTTP/1.1 RFC 2616, Section 10.5.5
HTTP_VERSION_NOT_SUPPORTED	505	HTTP/1.1, RFC 2616, Section 10.5.6
INSUFFICIENT_STORAGE	507	WEBDAV, RFC 2518, Section 10.6
NOT_EXTENDED	510	An HTTP Extension Framework, RFC 2774, Section 7

http.client.responses

This dictionary maps the HTTP 1.1 status codes to the W3C names.

Example: http.client.responses[http.client.NOT_FOUND] is 'Not Found'.

20.10.1. HTTPConnection Objects

HTTPConnection instances have the following methods:

HTTPConnection.request(method, url, body=None, headers={})

This will send a request to the server using the HTTP request method method and the selector url. If the body argument is present, it should be string or bytes object of data to send after the headers are finished. Strings are encoded as ISO-8859-1, the default charset for HTTP. To use other encodings, pass a bytes object. The Content-Length header is set to the length of the string.

The body may also be an open file object, in which case the contents of the file is sent; this file object should support fileno() and read() methods. The header Content-Length is automatically set to the length of the file as reported by stat.

The headers argument should be a mapping of extra HTTP headers to send with the request.

HTTPConnection.getresponse()

Should be called after a request is sent to get the response from the server. Returns an HTTPResponse instance.

注解

Note that you must have read the whole response before you can send a new request to the server.

HTTPConnection.set_debuglevel(level)

Set the debugging level. The default debug level is 0, meaning no debugging output is printed. Any value greater than 0 will cause all currently defined debug output to be printed to stdout. The debuglevel is passed to any new HTTPResponse objects that are created.

3.1 新版功能.

HTTPConnection.connect()

Connect to the server specified when the object was created.

HTTPConnection.close()

Close the connection to the server.

As an alternative to using the request() method described above, you can also send your request step by step, by using the four functions below.

HTTPConnection.putrequest(request, selector, skip_host=False, skip_accept_encoding=False)

This should be the first call after the connection to the server has been made. It sends a line to the server consisting of the request string, the selector string, and the HTTP version (HTTP/1.1). To disable automatic sending of Host: or Accept-Encoding: headers (for example to accept additional content encodings), specify skip_host or skip_accept_encoding with non-False values.

HTTPConnection.putheader(header, argument[, ...])

Send an RFC 822-style header to the server. It sends a line to the server consisting of the header, a colon and a space, and the first argument. If more arguments are given, continuation lines are sent, each consisting of a tab and an argument.

HTTPConnection.endheaders()

Send a blank line to the server, signalling the end of the headers.

HTTPConnection.send(data)

Send data to the server. This should be used directly only after the endheaders() method has been called and before getresponse() is called.

20.10.2. HTTPResponse Objects

An HTTPResponse instance wraps the HTTP response from the server. It provides access to the request headers and the entity body. The response is an iterable object and can be used in a with statement.

HTTPResponse.read([amt])

Reads and returns the response body, or up to the next amt bytes.

HTTPResponse.getheader(name, default=None)

Return the value of the header name, or default if there is no header matching name. If there is more than one header with the name name, return all of the values joined by ‘, ‘. If ‘default’ is any iterable other than a single string, its elements are similarly returned joined by commas.

HTTPResponse.getheaders()

Return a list of (header, value) tuples.

HTTPResponse.fileno()

Return the fileno of the underlying socket.

HTTPResponse.msg

A http.client.HTTPMessage instance containing the response headers. http.client.HTTPMessage is a subclass of email.message.Message.

HTTPResponse.version

HTTP protocol version used by server. 10 for HTTP/1.0, 11 for HTTP/1.1.

HTTPResponse.status

Status code returned by server.

HTTPResponse.reason

Reason phrase returned by server.

HTTPResponse.debuglevel

A debugging hook. If debuglevel is greater than zero, messages will be printed to stdout as the response is read and parsed.

20.10.3. Examples

Here is an example session that uses the GET method:

>>> import http.client
>>> conn = http.client.HTTPConnection("www.python.org")
>>> conn.request("GET", "/index.html")
>>> r1 = conn.getresponse()
>>> print(r1.status, r1.reason)
200 OK
>>> data1 = r1.read()
>>> conn.request("GET", "/parrot.spam")
>>> r2 = conn.getresponse()
>>> print(r2.status, r2.reason)
404 Not Found
>>> data2 = r2.read()
>>> conn.close()

Here is an example session that uses HEAD method. Note that HEAD method never returns any data.

>>> import http.client
>>> conn = http.client.HTTPConnection("www.python.org")
>>> conn.request("HEAD","/index.html")
>>> res = conn.getresponse()
>>> print(res.status, res.reason)
200 OK
>>> data = res.read()
>>> print(len(data))
0
>>> data == b''
True

Here is an example session that shows how to POST requests:

>>> import http.client, urllib.parse
>>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
>>> headers = {"Content-type": "application/x-www-form-urlencoded",
...            "Accept": "text/plain"}
>>> conn = http.client.HTTPConnection("musi-cal.mojam.com:80")
>>> conn.request("POST", "/cgi-bin/query", params, headers)
>>> response = conn.getresponse()
>>> print(response.status, response.reason)
200 OK
>>> data = response.read()
>>> conn.close()

20.10.4. HTTPMessage Objects

An http.client.HTTPMessage instance holds the headers from an HTTP response. It is implemented using the email.message.Message class.