935 lines
31 KiB
ReStructuredText
935 lines
31 KiB
ReStructuredText
:mod:`urllib2` --- extensible library for opening URLs
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======================================================
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.. module:: urllib2
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:synopsis: Next generation URL opening library.
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.. moduleauthor:: Jeremy Hylton <jhylton@users.sourceforge.net>
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.. sectionauthor:: Moshe Zadka <moshez@users.sourceforge.net>
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The :mod:`urllib2` module defines functions and classes which help in opening
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URLs (mostly HTTP) in a complex world --- basic and digest authentication,
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redirections, cookies and more.
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The :mod:`urllib2` module defines the following functions:
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.. function:: urlopen(url[, data][, timeout])
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Open the URL *url*, which can be either a string or a :class:`Request` object.
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*data* may be a string specifying additional data to send to the server, or
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``None`` if no such data is needed. Currently HTTP requests are the only ones
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that use *data*; the HTTP request will be a POST instead of a GET when the
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*data* parameter is provided. *data* should be a buffer in the standard
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:mimetype:`application/x-www-form-urlencoded` format. The
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:func:`urllib.urlencode` function takes a mapping or sequence of 2-tuples and
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returns a string in this format.
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The optional *timeout* parameter specifies a timeout in seconds for blocking
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operations like the connection attempt (if not specified, or passed as
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``None``, the global default timeout setting will be used). This actually
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only works for HTTP, HTTPS, FTP and FTPS connections.
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This function returns a file-like object with two additional methods:
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* :meth:`geturl` --- return the URL of the resource retrieved, commonly used to
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determine if a redirect was followed
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* :meth:`info` --- return the meta-information of the page, such as headers, in
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the form of an ``http.client.HTTPMessage`` instance
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(see `Quick Reference to HTTP Headers <http://www.cs.tut.fi/~jkorpela/http.html>`_)
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Raises :exc:`URLError` on errors.
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Note that ``None`` may be returned if no handler handles the request (though the
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default installed global :class:`OpenerDirector` uses :class:`UnknownHandler` to
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ensure this never happens).
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.. function:: install_opener(opener)
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Install an :class:`OpenerDirector` instance as the default global opener.
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Installing an opener is only necessary if you want urlopen to use that opener;
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otherwise, simply call :meth:`OpenerDirector.open` instead of :func:`urlopen`.
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The code does not check for a real :class:`OpenerDirector`, and any class with
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the appropriate interface will work.
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.. function:: build_opener([handler, ...])
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Return an :class:`OpenerDirector` instance, which chains the handlers in the
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order given. *handler*\s can be either instances of :class:`BaseHandler`, or
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subclasses of :class:`BaseHandler` (in which case it must be possible to call
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the constructor without any parameters). Instances of the following classes
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will be in front of the *handler*\s, unless the *handler*\s contain them,
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instances of them or subclasses of them: :class:`ProxyHandler`,
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:class:`UnknownHandler`, :class:`HTTPHandler`, :class:`HTTPDefaultErrorHandler`,
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:class:`HTTPRedirectHandler`, :class:`FTPHandler`, :class:`FileHandler`,
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:class:`HTTPErrorProcessor`.
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If the Python installation has SSL support (i.e., if the :mod:`ssl` module can be imported),
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:class:`HTTPSHandler` will also be added.
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A :class:`BaseHandler` subclass may also change its :attr:`handler_order`
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member variable to modify its position in the handlers list.
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The following exceptions are raised as appropriate:
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.. exception:: URLError
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The handlers raise this exception (or derived exceptions) when they run into a
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problem. It is a subclass of :exc:`IOError`.
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.. attribute:: reason
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The reason for this error. It can be a message string or another exception
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instance (:exc:`socket.error` for remote URLs, :exc:`OSError` for local
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URLs).
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.. exception:: HTTPError
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Though being an exception (a subclass of :exc:`URLError`), an :exc:`HTTPError`
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can also function as a non-exceptional file-like return value (the same thing
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that :func:`urlopen` returns). This is useful when handling exotic HTTP
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errors, such as requests for authentication.
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.. attribute:: code
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An HTTP status code as defined in `RFC 2616 <http://www.faqs.org/rfcs/rfc2616.html>`_.
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This numeric value corresponds to a value found in the dictionary of
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codes as found in :attr:`http.server.BaseHTTPRequestHandler.responses`.
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The following classes are provided:
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.. class:: Request(url[, data][, headers][, origin_req_host][, unverifiable])
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This class is an abstraction of a URL request.
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*url* should be a string containing a valid URL.
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*data* may be a string specifying additional data to send to the server, or
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``None`` if no such data is needed. Currently HTTP requests are the only ones
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that use *data*; the HTTP request will be a POST instead of a GET when the
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*data* parameter is provided. *data* should be a buffer in the standard
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:mimetype:`application/x-www-form-urlencoded` format. The
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:func:`urllib.urlencode` function takes a mapping or sequence of 2-tuples and
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returns a string in this format.
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*headers* should be a dictionary, and will be treated as if :meth:`add_header`
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was called with each key and value as arguments. This is often used to "spoof"
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the ``User-Agent`` header, which is used by a browser to identify itself --
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some HTTP servers only allow requests coming from common browsers as opposed
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to scripts. For example, Mozilla Firefox may identify itself as ``"Mozilla/5.0
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(X11; U; Linux i686) Gecko/20071127 Firefox/2.0.0.11"``, while :mod:`urllib2`'s
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default user agent string is ``"Python-urllib/2.6"`` (on Python 2.6).
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The final two arguments are only of interest for correct handling of third-party
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HTTP cookies:
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*origin_req_host* should be the request-host of the origin transaction, as
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defined by :rfc:`2965`. It defaults to ``http.cookiejar.request_host(self)``.
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This is the host name or IP address of the original request that was
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initiated by the user. For example, if the request is for an image in an
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HTML document, this should be the request-host of the request for the page
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containing the image.
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*unverifiable* should indicate whether the request is unverifiable, as defined
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by RFC 2965. It defaults to False. An unverifiable request is one whose URL
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the user did not have the option to approve. For example, if the request is for
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an image in an HTML document, and the user had no option to approve the
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automatic fetching of the image, this should be true.
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.. class:: OpenerDirector()
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The :class:`OpenerDirector` class opens URLs via :class:`BaseHandler`\ s chained
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together. It manages the chaining of handlers, and recovery from errors.
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.. class:: BaseHandler()
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This is the base class for all registered handlers --- and handles only the
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simple mechanics of registration.
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.. class:: HTTPDefaultErrorHandler()
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A class which defines a default handler for HTTP error responses; all responses
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are turned into :exc:`HTTPError` exceptions.
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.. class:: HTTPRedirectHandler()
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A class to handle redirections.
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.. class:: HTTPCookieProcessor([cookiejar])
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A class to handle HTTP Cookies.
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.. class:: ProxyHandler([proxies])
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Cause requests to go through a proxy. If *proxies* is given, it must be a
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dictionary mapping protocol names to URLs of proxies. The default is to read the
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list of proxies from the environment variables :envvar:`<protocol>_proxy`.
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To disable autodetected proxy pass an empty dictionary.
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.. class:: HTTPPasswordMgr()
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Keep a database of ``(realm, uri) -> (user, password)`` mappings.
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.. class:: HTTPPasswordMgrWithDefaultRealm()
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Keep a database of ``(realm, uri) -> (user, password)`` mappings. A realm of
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``None`` is considered a catch-all realm, which is searched if no other realm
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fits.
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.. class:: AbstractBasicAuthHandler([password_mgr])
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This is a mixin class that helps with HTTP authentication, both to the remote
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host and to a proxy. *password_mgr*, if given, should be something that is
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compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: HTTPBasicAuthHandler([password_mgr])
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Handle authentication with the remote host. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: ProxyBasicAuthHandler([password_mgr])
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Handle authentication with the proxy. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: AbstractDigestAuthHandler([password_mgr])
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This is a mixin class that helps with HTTP authentication, both to the remote
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host and to a proxy. *password_mgr*, if given, should be something that is
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compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: HTTPDigestAuthHandler([password_mgr])
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Handle authentication with the remote host. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: ProxyDigestAuthHandler([password_mgr])
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Handle authentication with the proxy. *password_mgr*, if given, should be
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something that is compatible with :class:`HTTPPasswordMgr`; refer to section
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:ref:`http-password-mgr` for information on the interface that must be
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supported.
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.. class:: HTTPHandler()
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A class to handle opening of HTTP URLs.
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.. class:: HTTPSHandler()
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A class to handle opening of HTTPS URLs.
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.. class:: FileHandler()
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Open local files.
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.. class:: FTPHandler()
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Open FTP URLs.
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.. class:: CacheFTPHandler()
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Open FTP URLs, keeping a cache of open FTP connections to minimize delays.
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.. class:: UnknownHandler()
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A catch-all class to handle unknown URLs.
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.. _request-objects:
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Request Objects
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---------------
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The following methods describe all of :class:`Request`'s public interface, and
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so all must be overridden in subclasses.
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.. method:: Request.add_data(data)
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Set the :class:`Request` data to *data*. This is ignored by all handlers except
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HTTP handlers --- and there it should be a byte string, and will change the
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request to be ``POST`` rather than ``GET``.
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.. method:: Request.get_method()
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Return a string indicating the HTTP request method. This is only meaningful for
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HTTP requests, and currently always returns ``'GET'`` or ``'POST'``.
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.. method:: Request.has_data()
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Return whether the instance has a non-\ ``None`` data.
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.. method:: Request.get_data()
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Return the instance's data.
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.. method:: Request.add_header(key, val)
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Add another header to the request. Headers are currently ignored by all
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handlers except HTTP handlers, where they are added to the list of headers sent
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to the server. Note that there cannot be more than one header with the same
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name, and later calls will overwrite previous calls in case the *key* collides.
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Currently, this is no loss of HTTP functionality, since all headers which have
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meaning when used more than once have a (header-specific) way of gaining the
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same functionality using only one header.
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.. method:: Request.add_unredirected_header(key, header)
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Add a header that will not be added to a redirected request.
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.. method:: Request.has_header(header)
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Return whether the instance has the named header (checks both regular and
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unredirected).
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.. method:: Request.get_full_url()
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Return the URL given in the constructor.
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.. method:: Request.get_type()
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Return the type of the URL --- also known as the scheme.
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.. method:: Request.get_host()
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Return the host to which a connection will be made.
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.. method:: Request.get_selector()
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Return the selector --- the part of the URL that is sent to the server.
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.. method:: Request.set_proxy(host, type)
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Prepare the request by connecting to a proxy server. The *host* and *type* will
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replace those of the instance, and the instance's selector will be the original
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URL given in the constructor.
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.. method:: Request.get_origin_req_host()
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Return the request-host of the origin transaction, as defined by :rfc:`2965`.
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See the documentation for the :class:`Request` constructor.
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.. method:: Request.is_unverifiable()
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Return whether the request is unverifiable, as defined by RFC 2965. See the
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documentation for the :class:`Request` constructor.
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.. _opener-director-objects:
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OpenerDirector Objects
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----------------------
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:class:`OpenerDirector` instances have the following methods:
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.. method:: OpenerDirector.add_handler(handler)
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*handler* should be an instance of :class:`BaseHandler`. The following methods
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are searched, and added to the possible chains (note that HTTP errors are a
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special case).
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* :meth:`protocol_open` --- signal that the handler knows how to open *protocol*
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URLs.
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* :meth:`http_error_type` --- signal that the handler knows how to handle HTTP
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errors with HTTP error code *type*.
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* :meth:`protocol_error` --- signal that the handler knows how to handle errors
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from (non-\ ``http``) *protocol*.
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* :meth:`protocol_request` --- signal that the handler knows how to pre-process
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*protocol* requests.
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* :meth:`protocol_response` --- signal that the handler knows how to
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post-process *protocol* responses.
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.. method:: OpenerDirector.open(url[, data][, timeout])
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Open the given *url* (which can be a request object or a string), optionally
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passing the given *data*. Arguments, return values and exceptions raised are
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the same as those of :func:`urlopen` (which simply calls the :meth:`open`
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method on the currently installed global :class:`OpenerDirector`). The
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optional *timeout* parameter specifies a timeout in seconds for blocking
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operations like the connection attempt (if not specified, or passed as
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``None``, the global default timeout setting will be used; this actually only
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works for HTTP, HTTPS, FTP and FTPS connections).
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.. method:: OpenerDirector.error(proto[, arg[, ...]])
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Handle an error of the given protocol. This will call the registered error
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handlers for the given protocol with the given arguments (which are protocol
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specific). The HTTP protocol is a special case which uses the HTTP response
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code to determine the specific error handler; refer to the :meth:`http_error_\*`
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methods of the handler classes.
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Return values and exceptions raised are the same as those of :func:`urlopen`.
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OpenerDirector objects open URLs in three stages:
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The order in which these methods are called within each stage is determined by
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sorting the handler instances.
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#. Every handler with a method named like :meth:`protocol_request` has that
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method called to pre-process the request.
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#. Handlers with a method named like :meth:`protocol_open` are called to handle
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the request. This stage ends when a handler either returns a non-\ :const:`None`
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value (ie. a response), or raises an exception (usually :exc:`URLError`).
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Exceptions are allowed to propagate.
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In fact, the above algorithm is first tried for methods named
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:meth:`default_open`. If all such methods return :const:`None`, the algorithm
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is repeated for methods named like :meth:`protocol_open`. If all such methods
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return :const:`None`, the algorithm is repeated for methods named
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:meth:`unknown_open`.
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Note that the implementation of these methods may involve calls of the parent
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:class:`OpenerDirector` instance's :meth:`.open` and :meth:`.error` methods.
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#. Every handler with a method named like :meth:`protocol_response` has that
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method called to post-process the response.
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.. _base-handler-objects:
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BaseHandler Objects
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-------------------
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:class:`BaseHandler` objects provide a couple of methods that are directly
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useful, and others that are meant to be used by derived classes. These are
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intended for direct use:
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.. method:: BaseHandler.add_parent(director)
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Add a director as parent.
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.. method:: BaseHandler.close()
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Remove any parents.
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The following members and methods should only be used by classes derived from
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:class:`BaseHandler`.
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.. note::
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The convention has been adopted that subclasses defining
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:meth:`protocol_request` or :meth:`protocol_response` methods are named
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:class:`\*Processor`; all others are named :class:`\*Handler`.
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.. attribute:: BaseHandler.parent
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A valid :class:`OpenerDirector`, which can be used to open using a different
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protocol, or handle errors.
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.. method:: BaseHandler.default_open(req)
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This method is *not* defined in :class:`BaseHandler`, but subclasses should
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define it if they want to catch all URLs.
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This method, if implemented, will be called by the parent
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:class:`OpenerDirector`. It should return a file-like object as described in
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the return value of the :meth:`open` of :class:`OpenerDirector`, or ``None``.
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It should raise :exc:`URLError`, unless a truly exceptional thing happens (for
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example, :exc:`MemoryError` should not be mapped to :exc:`URLError`).
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This method will be called before any protocol-specific open method.
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.. method:: BaseHandler.protocol_open(req)
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:noindex:
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This method is *not* defined in :class:`BaseHandler`, but subclasses should
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define it if they want to handle URLs with the given protocol.
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This method, if defined, will be called by the parent :class:`OpenerDirector`.
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Return values should be the same as for :meth:`default_open`.
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.. method:: BaseHandler.unknown_open(req)
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This method is *not* defined in :class:`BaseHandler`, but subclasses should
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define it if they want to catch all URLs with no specific registered handler to
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open it.
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This method, if implemented, will be called by the :attr:`parent`
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:class:`OpenerDirector`. Return values should be the same as for
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:meth:`default_open`.
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.. method:: BaseHandler.http_error_default(req, fp, code, msg, hdrs)
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This method is *not* defined in :class:`BaseHandler`, but subclasses should
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override it if they intend to provide a catch-all for otherwise unhandled HTTP
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errors. It will be called automatically by the :class:`OpenerDirector` getting
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the error, and should not normally be called in other circumstances.
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*req* will be a :class:`Request` object, *fp* will be a file-like object with
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the HTTP error body, *code* will be the three-digit code of the error, *msg*
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will be the user-visible explanation of the code and *hdrs* will be a mapping
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object with the headers of the error.
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Return values and exceptions raised should be the same as those of
|
|
:func:`urlopen`.
|
|
|
|
|
|
.. method:: BaseHandler.http_error_nnn(req, fp, code, msg, hdrs)
|
|
|
|
*nnn* should be a three-digit HTTP error code. This method is also not defined
|
|
in :class:`BaseHandler`, but will be called, if it exists, on an instance of a
|
|
subclass, when an HTTP error with code *nnn* occurs.
|
|
|
|
Subclasses should override this method to handle specific HTTP errors.
|
|
|
|
Arguments, return values and exceptions raised should be the same as for
|
|
:meth:`http_error_default`.
|
|
|
|
|
|
.. method:: BaseHandler.protocol_request(req)
|
|
:noindex:
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to pre-process requests of the given protocol.
|
|
|
|
This method, if defined, will be called by the parent :class:`OpenerDirector`.
|
|
*req* will be a :class:`Request` object. The return value should be a
|
|
:class:`Request` object.
|
|
|
|
|
|
.. method:: BaseHandler.protocol_response(req, response)
|
|
:noindex:
|
|
|
|
This method is *not* defined in :class:`BaseHandler`, but subclasses should
|
|
define it if they want to post-process responses of the given protocol.
|
|
|
|
This method, if defined, will be called by the parent :class:`OpenerDirector`.
|
|
*req* will be a :class:`Request` object. *response* will be an object
|
|
implementing the same interface as the return value of :func:`urlopen`. The
|
|
return value should implement the same interface as the return value of
|
|
:func:`urlopen`.
|
|
|
|
|
|
.. _http-redirect-handler:
|
|
|
|
HTTPRedirectHandler Objects
|
|
---------------------------
|
|
|
|
.. note::
|
|
|
|
Some HTTP redirections require action from this module's client code. If this
|
|
is the case, :exc:`HTTPError` is raised. See :rfc:`2616` for details of the
|
|
precise meanings of the various redirection codes.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.redirect_request(req, fp, code, msg, hdrs)
|
|
|
|
Return a :class:`Request` or ``None`` in response to a redirect. This is called
|
|
by the default implementations of the :meth:`http_error_30\*` methods when a
|
|
redirection is received from the server. If a redirection should take place,
|
|
return a new :class:`Request` to allow :meth:`http_error_30\*` to perform the
|
|
redirect. Otherwise, raise :exc:`HTTPError` if no other handler should try to
|
|
handle this URL, or return ``None`` if you can't but another handler might.
|
|
|
|
.. note::
|
|
|
|
The default implementation of this method does not strictly follow :rfc:`2616`,
|
|
which says that 301 and 302 responses to ``POST`` requests must not be
|
|
automatically redirected without confirmation by the user. In reality, browsers
|
|
do allow automatic redirection of these responses, changing the POST to a
|
|
``GET``, and the default implementation reproduces this behavior.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_301(req, fp, code, msg, hdrs)
|
|
|
|
Redirect to the ``Location:`` URL. This method is called by the parent
|
|
:class:`OpenerDirector` when getting an HTTP 'moved permanently' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_302(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'found' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_303(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'see other' response.
|
|
|
|
|
|
.. method:: HTTPRedirectHandler.http_error_307(req, fp, code, msg, hdrs)
|
|
|
|
The same as :meth:`http_error_301`, but called for the 'temporary redirect'
|
|
response.
|
|
|
|
|
|
.. _http-cookie-processor:
|
|
|
|
HTTPCookieProcessor Objects
|
|
---------------------------
|
|
|
|
:class:`HTTPCookieProcessor` instances have one attribute:
|
|
|
|
.. attribute:: HTTPCookieProcessor.cookiejar
|
|
|
|
The :class:`http.cookiejar.CookieJar` in which cookies are stored.
|
|
|
|
|
|
.. _proxy-handler:
|
|
|
|
ProxyHandler Objects
|
|
--------------------
|
|
|
|
|
|
.. method:: ProxyHandler.protocol_open(request)
|
|
:noindex:
|
|
|
|
The :class:`ProxyHandler` will have a method :meth:`protocol_open` for every
|
|
*protocol* which has a proxy in the *proxies* dictionary given in the
|
|
constructor. The method will modify requests to go through the proxy, by
|
|
calling ``request.set_proxy()``, and call the next handler in the chain to
|
|
actually execute the protocol.
|
|
|
|
|
|
.. _http-password-mgr:
|
|
|
|
HTTPPasswordMgr Objects
|
|
-----------------------
|
|
|
|
These methods are available on :class:`HTTPPasswordMgr` and
|
|
:class:`HTTPPasswordMgrWithDefaultRealm` objects.
|
|
|
|
|
|
.. method:: HTTPPasswordMgr.add_password(realm, uri, user, passwd)
|
|
|
|
*uri* can be either a single URI, or a sequence of URIs. *realm*, *user* and
|
|
*passwd* must be strings. This causes ``(user, passwd)`` to be used as
|
|
authentication tokens when authentication for *realm* and a super-URI of any of
|
|
the given URIs is given.
|
|
|
|
|
|
.. method:: HTTPPasswordMgr.find_user_password(realm, authuri)
|
|
|
|
Get user/password for given realm and URI, if any. This method will return
|
|
``(None, None)`` if there is no matching user/password.
|
|
|
|
For :class:`HTTPPasswordMgrWithDefaultRealm` objects, the realm ``None`` will be
|
|
searched if the given *realm* has no matching user/password.
|
|
|
|
|
|
.. _abstract-basic-auth-handler:
|
|
|
|
AbstractBasicAuthHandler Objects
|
|
--------------------------------
|
|
|
|
|
|
.. method:: AbstractBasicAuthHandler.http_error_auth_reqed(authreq, host, req, headers)
|
|
|
|
Handle an authentication request by getting a user/password pair, and re-trying
|
|
the request. *authreq* should be the name of the header where the information
|
|
about the realm is included in the request, *host* specifies the URL and path to
|
|
authenticate for, *req* should be the (failed) :class:`Request` object, and
|
|
*headers* should be the error headers.
|
|
|
|
*host* is either an authority (e.g. ``"python.org"``) or a URL containing an
|
|
authority component (e.g. ``"http://python.org/"``). In either case, the
|
|
authority must not contain a userinfo component (so, ``"python.org"`` and
|
|
``"python.org:80"`` are fine, ``"joe:password@python.org"`` is not).
|
|
|
|
|
|
.. _http-basic-auth-handler:
|
|
|
|
HTTPBasicAuthHandler Objects
|
|
----------------------------
|
|
|
|
|
|
.. method:: HTTPBasicAuthHandler.http_error_401(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _proxy-basic-auth-handler:
|
|
|
|
ProxyBasicAuthHandler Objects
|
|
-----------------------------
|
|
|
|
|
|
.. method:: ProxyBasicAuthHandler.http_error_407(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _abstract-digest-auth-handler:
|
|
|
|
AbstractDigestAuthHandler Objects
|
|
---------------------------------
|
|
|
|
|
|
.. method:: AbstractDigestAuthHandler.http_error_auth_reqed(authreq, host, req, headers)
|
|
|
|
*authreq* should be the name of the header where the information about the realm
|
|
is included in the request, *host* should be the host to authenticate to, *req*
|
|
should be the (failed) :class:`Request` object, and *headers* should be the
|
|
error headers.
|
|
|
|
|
|
.. _http-digest-auth-handler:
|
|
|
|
HTTPDigestAuthHandler Objects
|
|
-----------------------------
|
|
|
|
|
|
.. method:: HTTPDigestAuthHandler.http_error_401(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _proxy-digest-auth-handler:
|
|
|
|
ProxyDigestAuthHandler Objects
|
|
------------------------------
|
|
|
|
|
|
.. method:: ProxyDigestAuthHandler.http_error_407(req, fp, code, msg, hdrs)
|
|
|
|
Retry the request with authentication information, if available.
|
|
|
|
|
|
.. _http-handler-objects:
|
|
|
|
HTTPHandler Objects
|
|
-------------------
|
|
|
|
|
|
.. method:: HTTPHandler.http_open(req)
|
|
|
|
Send an HTTP request, which can be either GET or POST, depending on
|
|
``req.has_data()``.
|
|
|
|
|
|
.. _https-handler-objects:
|
|
|
|
HTTPSHandler Objects
|
|
--------------------
|
|
|
|
|
|
.. method:: HTTPSHandler.https_open(req)
|
|
|
|
Send an HTTPS request, which can be either GET or POST, depending on
|
|
``req.has_data()``.
|
|
|
|
|
|
.. _file-handler-objects:
|
|
|
|
FileHandler Objects
|
|
-------------------
|
|
|
|
|
|
.. method:: FileHandler.file_open(req)
|
|
|
|
Open the file locally, if there is no host name, or the host name is
|
|
``'localhost'``. Change the protocol to ``ftp`` otherwise, and retry opening it
|
|
using :attr:`parent`.
|
|
|
|
|
|
.. _ftp-handler-objects:
|
|
|
|
FTPHandler Objects
|
|
------------------
|
|
|
|
|
|
.. method:: FTPHandler.ftp_open(req)
|
|
|
|
Open the FTP file indicated by *req*. The login is always done with empty
|
|
username and password.
|
|
|
|
|
|
.. _cacheftp-handler-objects:
|
|
|
|
CacheFTPHandler Objects
|
|
-----------------------
|
|
|
|
:class:`CacheFTPHandler` objects are :class:`FTPHandler` objects with the
|
|
following additional methods:
|
|
|
|
|
|
.. method:: CacheFTPHandler.setTimeout(t)
|
|
|
|
Set timeout of connections to *t* seconds.
|
|
|
|
|
|
.. method:: CacheFTPHandler.setMaxConns(m)
|
|
|
|
Set maximum number of cached connections to *m*.
|
|
|
|
|
|
.. _unknown-handler-objects:
|
|
|
|
UnknownHandler Objects
|
|
----------------------
|
|
|
|
|
|
.. method:: UnknownHandler.unknown_open()
|
|
|
|
Raise a :exc:`URLError` exception.
|
|
|
|
|
|
.. _http-error-processor-objects:
|
|
|
|
HTTPErrorProcessor Objects
|
|
--------------------------
|
|
|
|
.. method:: HTTPErrorProcessor.unknown_open()
|
|
|
|
Process HTTP error responses.
|
|
|
|
For 200 error codes, the response object is returned immediately.
|
|
|
|
For non-200 error codes, this simply passes the job on to the
|
|
:meth:`protocol_error_code` handler methods, via :meth:`OpenerDirector.error`.
|
|
Eventually, :class:`urllib2.HTTPDefaultErrorHandler` will raise an
|
|
:exc:`HTTPError` if no other handler handles the error.
|
|
|
|
|
|
.. _urllib2-examples:
|
|
|
|
Examples
|
|
--------
|
|
|
|
This example gets the python.org main page and displays the first 100 bytes of
|
|
it::
|
|
|
|
>>> import urllib2
|
|
>>> f = urllib2.urlopen('http://www.python.org/')
|
|
>>> print(f.read(100))
|
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
|
|
<?xml-stylesheet href="./css/ht2html
|
|
|
|
Here we are sending a data-stream to the stdin of a CGI and reading the data it
|
|
returns to us. Note that this example will only work when the Python
|
|
installation supports SSL. ::
|
|
|
|
>>> import urllib2
|
|
>>> req = urllib2.Request(url='https://localhost/cgi-bin/test.cgi',
|
|
... data='This data is passed to stdin of the CGI')
|
|
>>> f = urllib2.urlopen(req)
|
|
>>> print(f.read())
|
|
Got Data: "This data is passed to stdin of the CGI"
|
|
|
|
The code for the sample CGI used in the above example is::
|
|
|
|
#!/usr/bin/env python
|
|
import sys
|
|
data = sys.stdin.read()
|
|
print('Content-type: text-plain\n\nGot Data: "%s"' % data)
|
|
|
|
Use of Basic HTTP Authentication::
|
|
|
|
import urllib2
|
|
# Create an OpenerDirector with support for Basic HTTP Authentication...
|
|
auth_handler = urllib2.HTTPBasicAuthHandler()
|
|
auth_handler.add_password(realm='PDQ Application',
|
|
uri='https://mahler:8092/site-updates.py',
|
|
user='klem',
|
|
passwd='kadidd!ehopper')
|
|
opener = urllib2.build_opener(auth_handler)
|
|
# ...and install it globally so it can be used with urlopen.
|
|
urllib2.install_opener(opener)
|
|
urllib2.urlopen('http://www.example.com/login.html')
|
|
|
|
:func:`build_opener` provides many handlers by default, including a
|
|
:class:`ProxyHandler`. By default, :class:`ProxyHandler` uses the environment
|
|
variables named ``<scheme>_proxy``, where ``<scheme>`` is the URL scheme
|
|
involved. For example, the :envvar:`http_proxy` environment variable is read to
|
|
obtain the HTTP proxy's URL.
|
|
|
|
This example replaces the default :class:`ProxyHandler` with one that uses
|
|
programatically-supplied proxy URLs, and adds proxy authorization support with
|
|
:class:`ProxyBasicAuthHandler`. ::
|
|
|
|
proxy_handler = urllib2.ProxyHandler({'http': 'http://www.example.com:3128/'})
|
|
proxy_auth_handler = urllib2.HTTPBasicAuthHandler()
|
|
proxy_auth_handler.add_password('realm', 'host', 'username', 'password')
|
|
|
|
opener = build_opener(proxy_handler, proxy_auth_handler)
|
|
# This time, rather than install the OpenerDirector, we use it directly:
|
|
opener.open('http://www.example.com/login.html')
|
|
|
|
Adding HTTP headers:
|
|
|
|
Use the *headers* argument to the :class:`Request` constructor, or::
|
|
|
|
import urllib2
|
|
req = urllib2.Request('http://www.example.com/')
|
|
req.add_header('Referer', 'http://www.python.org/')
|
|
r = urllib2.urlopen(req)
|
|
|
|
:class:`OpenerDirector` automatically adds a :mailheader:`User-Agent` header to
|
|
every :class:`Request`. To change this::
|
|
|
|
import urllib2
|
|
opener = urllib2.build_opener()
|
|
opener.addheaders = [('User-agent', 'Mozilla/5.0')]
|
|
opener.open('http://www.example.com/')
|
|
|
|
Also, remember that a few standard headers (:mailheader:`Content-Length`,
|
|
:mailheader:`Content-Type` and :mailheader:`Host`) are added when the
|
|
:class:`Request` is passed to :func:`urlopen` (or :meth:`OpenerDirector.open`).
|
|
|