20.7. "httplib" — HTTP protocol client
**************************************

備註: The "httplib" module has been renamed to "http.client" in
  Python 3. The *2to3* tool will automatically adapt imports when
  converting your sources to Python 3.

**Source code:** Lib/httplib.py

======================================================================

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

也參考: The Requests package is recommended for a higher-level HTTP
  client interface.

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

備註: The public interface for this module changed substantially in
  Python 2.0.  The "HTTP" class is retained only for backward
  compatibility with 1.5.2.  It should not be used in new code.  Refer
  to the online docstrings for usage.

The module provides the following classes:

class httplib.HTTPConnection(host[, port[, strict[, timeout[, source_address]]]])

   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). The optional
   *source_address* parameter may be a tuple of a (host, port) to use
   as the source address the HTTP connection is made from.

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

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

   2.0 版新加入.

   2.6 版更變: *timeout* was added.

   2.7 版更變: *source_address* was added.

class httplib.HTTPSConnection(host[, port[, key_file[, cert_file[, strict[, timeout[, source_address[, context]]]]]]])

   A subclass of "HTTPConnection" that uses SSL for communication with
   secure servers.  Default port is "443".  If *context* is specified,
   it must be a "ssl.SSLContext" instance describing the various SSL
   options.

   *key_file* and *cert_file* are deprecated, please use
   "ssl.SSLContext.load_cert_chain()" instead, or let
   "ssl.create_default_context()" select the system’s trusted CA
   certificates for you.

   Please read Security considerations for more information on best
   practices.

   2.0 版新加入.

   2.6 版更變: *timeout* was added.

   2.7 版更變: *source_address* was added.

   2.7.9 版更變: *context* was added.This class now performs all the
   necessary certificate and hostname checks by default. To revert to
   the previous, unverified, behavior
   "ssl._create_unverified_context()" can be passed to the *context*
   parameter.

class httplib.HTTPResponse(sock, debuglevel=0, strict=0)

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

   2.0 版新加入.

class httplib.HTTPMessage

   An "HTTPMessage" instance is used to hold the headers from an HTTP
   response. It is implemented using the "mimetools.Message" class and
   provides utility functions to deal with HTTP Headers. It is not
   directly instantiated by the users.

The following exceptions are raised as appropriate:

exception httplib.HTTPException

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

   2.0 版新加入.

exception httplib.NotConnected

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.InvalidURL

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

   2.3 版新加入.

exception httplib.UnknownProtocol

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.UnknownTransferEncoding

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.UnimplementedFileMode

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.IncompleteRead

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.ImproperConnectionState

   A subclass of "HTTPException".

   2.0 版新加入.

exception httplib.CannotSendRequest

   A subclass of "ImproperConnectionState".

   2.0 版新加入.

exception httplib.CannotSendHeader

   A subclass of "ImproperConnectionState".

   2.0 版新加入.

exception httplib.ResponseNotReady

   A subclass of "ImproperConnectionState".

   2.0 版新加入.

exception httplib.BadStatusLine

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

   2.0 版新加入.

The constants defined in this module are:

httplib.HTTP_PORT

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

httplib.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                    |
+--------------------------------------------+-----------+-------------------------------------------------------------------------+

httplib.responses

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

   Example: "httplib.responses[httplib.NOT_FOUND]" is "'Not Found'".

   2.5 版新加入.


20.7.1. HTTPConnection Objects
==============================

"HTTPConnection" instances have the following methods:

HTTPConnection.request(method, url[, body[, 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 a string of data to send after the headers
   are finished. Alternatively, it may 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 *headers*
   argument should be a mapping of extra HTTP headers to send with the
   request.

   If one is not provided in *headers*, a "Content-Length" header is
   added automatically for all methods if the length of the body can
   be determined, either from the length of the "str" representation,
   or from the reported size of the file on disk. If *body* is "None"
   the header is not set except for methods that expect a body ("PUT",
   "POST", and "PATCH") in which case it is set to "0".

   2.6 版更變: *body* can be a file object.

HTTPConnection.getresponse()

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

   備註: 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 amount of debugging output printed).
   The default debug level is "0", meaning no debugging output is
   printed.

HTTPConnection.set_tunnel(host, port=None, headers=None)

   Set the host and the port for HTTP Connect Tunnelling. Normally
   used when it is required to do HTTPS Connection through a proxy
   server.

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

   2.7 版新加入.

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[, skip_accept_encoding]])

   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.

   2.4 版更變: *skip_accept_encoding* argument added.

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(message_body=None)

   Send a blank line to the server, signalling the end of the headers.
   The optional *message_body* argument can be used to pass a message
   body associated with the request.  The message body will be sent in
   the same packet as the message headers if it is string, otherwise
   it is sent in a separate packet.

   2.7 版更變: *message_body* was added.

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.


20.7.2. HTTPResponse Objects
============================

"HTTPResponse" instances have the following methods and attributes:

HTTPResponse.read([amt])

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

HTTPResponse.getheader(name[, default])

   Get the contents of the header *name*, or *default* if there is no
   matching header.

HTTPResponse.getheaders()

   Return a list of (header, value) tuples.

   2.4 版新加入.

HTTPResponse.fileno()

   Returns the "fileno" of the underlying socket.

HTTPResponse.msg

   A "mimetools.Message" instance containing the response headers.

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.


20.7.3. Examples
================

Here is an example session that uses the "GET" method:

   >>> import httplib
   >>> conn = httplib.HTTPSConnection("www.python.org")
   >>> conn.request("GET", "/")
   >>> r1 = conn.getresponse()
   >>> print r1.status, r1.reason
   200 OK
   >>> data1 = r1.read()
   >>> conn.request("GET", "/")
   >>> r2 = conn.getresponse()
   >>> print r2.status, r2.reason
   404 Not Found
   >>> data2 = r2.read()
   >>> conn.close()

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

   >>> import httplib
   >>> conn = httplib.HTTPSConnection("www.python.org")
   >>> conn.request("HEAD","/")
   >>> res = conn.getresponse()
   >>> print res.status, res.reason
   200 OK
   >>> data = res.read()
   >>> print len(data)
   0
   >>> data == ''
   True

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

   >>> import httplib, urllib
   >>> params = urllib.urlencode({'@number': 12524, '@type': 'issue', '@action': 'show'})
   >>> headers = {"Content-type": "application/x-www-form-urlencoded",
   ...            "Accept": "text/plain"}
   >>> conn = httplib.HTTPConnection("bugs.python.org")
   >>> conn.request("POST", "", params, headers)
   >>> response = conn.getresponse()
   >>> print response.status, response.reason
   302 Found
   >>> data = response.read()
   >>> data
   'Redirecting to <a href="http://bugs.python.org/issue12524">http://bugs.python.org/issue12524</a>'
   >>> conn.close()

Client side "HTTP PUT" requests are very similar to "POST" requests.
The difference lies only the server side where HTTP server will allow
resources to be created via "PUT" request. Here is an example session
that shows how to do "PUT" request using httplib:

   >>> # This creates an HTTP message
   >>> # with the content of BODY as the enclosed representation
   >>> # for the resource http://localhost:8080/foobar
   ...
   >>> import httplib
   >>> BODY = "***filecontents***"
   >>> conn = httplib.HTTPConnection("localhost", 8080)
   >>> conn.request("PUT", "/file", BODY)
   >>> response = conn.getresponse()
   >>> print response.status, response.reason
   200, OK
