urllib.request
--- Extensible library for opening URLs¶
Source code: Lib/urllib/request.py
The urllib.request
module defines functions and classes which help in
opening URLs (mostly HTTP) in a complex world --- basic and digest
authentication, redirections, cookies and more.
也參考
The Requests package is recommended for a higher-level HTTP client interface.
The urllib.request
module defines the following functions:
-
urllib.request.
urlopen
(url, data=None, [timeout, ]*, cafile=None, capath=None, cadefault=False, context=None)¶ Open the URL url, which can be either a string or a
Request
object.data must be an object specifying additional data to be sent to the server, or
None
if no such data is needed. SeeRequest
for details.urllib.request module uses HTTP/1.1 and includes
Connection:close
header in its HTTP requests.The optional timeout parameter specifies a timeout in seconds for blocking operations like the connection attempt (if not specified, the global default timeout setting will be used). This actually only works for HTTP, HTTPS and FTP connections.
If context is specified, it must be a
ssl.SSLContext
instance describing the various SSL options. SeeHTTPSConnection
for more details.The optional cafile and capath parameters specify a set of trusted CA certificates for HTTPS requests. cafile should point to a single file containing a bundle of CA certificates, whereas capath should point to a directory of hashed certificate files. More information can be found in
ssl.SSLContext.load_verify_locations()
.The cadefault parameter is ignored.
This function always returns an object which can work as a context manager and has methods such as
geturl()
--- return the URL of the resource retrieved, commonly used to determine if a redirect was followedinfo()
--- return the meta-information of the page, such as headers, in the form of anemail.message_from_string()
instance (see Quick Reference to HTTP Headers)getcode()
-- return the HTTP status code of the response.
For HTTP and HTTPS URLs, this function returns a
http.client.HTTPResponse
object slightly modified. In addition to the three new methods above, the msg attribute contains the same information as thereason
attribute --- the reason phrase returned by server --- instead of the response headers as it is specified in the documentation forHTTPResponse
.For FTP, file, and data URLs and requests explicitly handled by legacy
URLopener
andFancyURLopener
classes, this function returns aurllib.response.addinfourl
object.Raises
URLError
on protocol errors.Note that
None
may be returned if no handler handles the request (though the default installed globalOpenerDirector
usesUnknownHandler
to ensure this never happens).In addition, if proxy settings are detected (for example, when a
*_proxy
environment variable likehttp_proxy
is set),ProxyHandler
is default installed and makes sure the requests are handled through the proxy.The legacy
urllib.urlopen
function from Python 2.6 and earlier has been discontinued;urllib.request.urlopen()
corresponds to the oldurllib2.urlopen
. Proxy handling, which was done by passing a dictionary parameter tourllib.urlopen
, can be obtained by usingProxyHandler
objects.3.2 版更變: cafile and capath were added.
3.2 版更變: HTTPS virtual hosts are now supported if possible (that is, if
ssl.HAS_SNI
is true).3.2 版新加入: data can be an iterable object.
3.3 版更變: cadefault was added.
3.4.3 版更變: context was added.
3.6 版後已棄用: cafile, capath and cadefault are deprecated in favor of context. Please use
ssl.SSLContext.load_cert_chain()
instead, or letssl.create_default_context()
select the system's trusted CA certificates for you.
-
urllib.request.
install_opener
(opener)¶ Install an
OpenerDirector
instance as the default global opener. Installing an opener is only necessary if you want urlopen to use that opener; otherwise, simply callOpenerDirector.open()
instead ofurlopen()
. The code does not check for a realOpenerDirector
, and any class with the appropriate interface will work.
-
urllib.request.
build_opener
([handler, ...])¶ Return an
OpenerDirector
instance, which chains the handlers in the order given. handlers can be either instances ofBaseHandler
, or subclasses ofBaseHandler
(in which case it must be possible to call the constructor without any parameters). Instances of the following classes will be in front of the handlers, unless the handlers contain them, instances of them or subclasses of them:ProxyHandler
(if proxy settings are detected),UnknownHandler
,HTTPHandler
,HTTPDefaultErrorHandler
,HTTPRedirectHandler
,FTPHandler
,FileHandler
,HTTPErrorProcessor
.If the Python installation has SSL support (i.e., if the
ssl
module can be imported),HTTPSHandler
will also be added.A
BaseHandler
subclass may also change itshandler_order
attribute to modify its position in the handlers list.
-
urllib.request.
pathname2url
(path)¶ Convert the pathname path from the local syntax for a path to the form used in the path component of a URL. This does not produce a complete URL. The return value will already be quoted using the
quote()
function.
-
urllib.request.
url2pathname
(path)¶ Convert the path component path from a percent-encoded URL to the local syntax for a path. This does not accept a complete URL. This function uses
unquote()
to decode path.
-
urllib.request.
getproxies
()¶ This helper function returns a dictionary of scheme to proxy server URL mappings. It scans the environment for variables named
<scheme>_proxy
, in a case insensitive approach, for all operating systems first, and when it cannot find it, looks for proxy information from Mac OSX System Configuration for Mac OS X and Windows Systems Registry for Windows. If both lowercase and uppercase environment variables exist (and disagree), lowercase is preferred.備註
If the environment variable
REQUEST_METHOD
is set, which usually indicates your script is running in a CGI environment, the environment variableHTTP_PROXY
(uppercase_PROXY
) will be ignored. This is because that variable can be injected by a client using the "Proxy:" HTTP header. If you need to use an HTTP proxy in a CGI environment, either useProxyHandler
explicitly, or make sure the variable name is in lowercase (or at least the_proxy
suffix).
The following classes are provided:
-
class
urllib.request.
Request
(url, data=None, headers={}, origin_req_host=None, unverifiable=False, method=None)¶ This class is an abstraction of a URL request.
url should be a string containing a valid URL.
data must be an object specifying additional data to send to the server, or
None
if no such data is needed. Currently HTTP requests are the only ones that use data. The supported object types include bytes, file-like objects, and iterables. If noContent-Length
norTransfer-Encoding
header field has been provided,HTTPHandler
will set these headers according to the type of data.Content-Length
will be used to send bytes objects, whileTransfer-Encoding: chunked
as specified in RFC 7230, Section 3.3.1 will be used to send files and other iterables.For an HTTP POST request method, data should be a buffer in the standard application/x-www-form-urlencoded format. The
urllib.parse.urlencode()
function takes a mapping or sequence of 2-tuples and returns an ASCII string in this format. It should be encoded to bytes before being used as the data parameter.headers should be a dictionary, and will be treated as if
add_header()
was called with each key and value as arguments. This is often used to "spoof" theUser-Agent
header value, which is used by a browser to identify itself -- some HTTP servers only allow requests coming from common browsers as opposed to scripts. For example, Mozilla Firefox may identify itself as"Mozilla/5.0 (X11; U; Linux i686) Gecko/20071127 Firefox/2.0.0.11"
, whileurllib
's default user agent string is"Python-urllib/2.6"
(on Python 2.6).An appropriate
Content-Type
header should be included if the data argument is present. If this header has not been provided and data is not None,Content-Type: application/x-www-form-urlencoded
will be added as a default.The next two arguments are only of interest for correct handling of third-party HTTP cookies:
origin_req_host should be the request-host of the origin transaction, as defined by RFC 2965. It defaults to
http.cookiejar.request_host(self)
. This is the host name or IP address of the original request that was initiated by the user. For example, if the request is for an image in an HTML document, this should be the request-host of the request for the page containing the image.unverifiable should indicate whether the request is unverifiable, as defined by RFC 2965. It defaults to
False
. An unverifiable request is one whose URL the user did not have the option to approve. For example, if the request is for an image in an HTML document, and the user had no option to approve the automatic fetching of the image, this should be true.method should be a string that indicates the HTTP request method that will be used (e.g.
'HEAD'
). If provided, its value is stored in themethod
attribute and is used byget_method()
. The default is'GET'
if data isNone
or'POST'
otherwise. Subclasses may indicate a different default method by setting themethod
attribute in the class itself.備註
The request will not work as expected if the data object is unable to deliver its content more than once (e.g. a file or an iterable that can produce the content only once) and the request is retried for HTTP redirects or authentication. The data is sent to the HTTP server right away after the headers. There is no support for a 100-continue expectation in the library.
3.3 版更變:
Request.method
argument is added to the Request class.3.4 版更變: Default
Request.method
may be indicated at the class level.3.6 版更變: Do not raise an error if the
Content-Length
has not been provided and data is neitherNone
nor a bytes object. Fall back to use chunked transfer encoding instead.
-
class
urllib.request.
OpenerDirector
¶ The
OpenerDirector
class opens URLs viaBaseHandler
s chained together. It manages the chaining of handlers, and recovery from errors.
-
class
urllib.request.
BaseHandler
¶ This is the base class for all registered handlers --- and handles only the simple mechanics of registration.
-
class
urllib.request.
HTTPDefaultErrorHandler
¶ A class which defines a default handler for HTTP error responses; all responses are turned into
HTTPError
exceptions.
-
class
urllib.request.
HTTPRedirectHandler
¶ A class to handle redirections.
-
class
urllib.request.
HTTPCookieProcessor
(cookiejar=None)¶ A class to handle HTTP Cookies.
-
class
urllib.request.
ProxyHandler
(proxies=None)¶ Cause requests to go through a proxy. If proxies is given, it must be a dictionary mapping protocol names to URLs of proxies. The default is to read the list of proxies from the environment variables
<protocol>_proxy
. If no proxy environment variables are set, then in a Windows environment proxy settings are obtained from the registry's Internet Settings section, and in a Mac OS X environment proxy information is retrieved from the OS X System Configuration Framework.To disable autodetected proxy pass an empty dictionary.
The
no_proxy
environment variable can be used to specify hosts which shouldn't be reached via proxy; if set, it should be a comma-separated list of hostname suffixes, optionally with:port
appended, for examplecern.ch,ncsa.uiuc.edu,some.host:8080
.備註
HTTP_PROXY
will be ignored if a variableREQUEST_METHOD
is set; see the documentation ongetproxies()
.
-
class
urllib.request.
HTTPPasswordMgr
¶ Keep a database of
(realm, uri) -> (user, password)
mappings.
-
class
urllib.request.
HTTPPasswordMgrWithDefaultRealm
¶ Keep a database of
(realm, uri) -> (user, password)
mappings. A realm ofNone
is considered a catch-all realm, which is searched if no other realm fits.
-
class
urllib.request.
HTTPPasswordMgrWithPriorAuth
¶ A variant of
HTTPPasswordMgrWithDefaultRealm
that also has a database ofuri -> is_authenticated
mappings. Can be used by a BasicAuth handler to determine when to send authentication credentials immediately instead of waiting for a401
response first.3.5 版新加入.
-
class
urllib.request.
AbstractBasicAuthHandler
(password_mgr=None)¶ This is a mixin class that helps with HTTP authentication, both to the remote host and to a proxy. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported. If passwd_mgr also providesis_authenticated
andupdate_authenticated
methods (see HTTPPasswordMgrWithPriorAuth Objects), then the handler will use theis_authenticated
result for a given URI to determine whether or not to send authentication credentials with the request. Ifis_authenticated
returnsTrue
for the URI, credentials are sent. Ifis_authenticated
isFalse
, credentials are not sent, and then if a401
response is received the request is re-sent with the authentication credentials. If authentication succeeds,update_authenticated
is called to setis_authenticated
True
for the URI, so that subsequent requests to the URI or any of its super-URIs will automatically include the authentication credentials.3.5 版新加入: Added
is_authenticated
support.
-
class
urllib.request.
HTTPBasicAuthHandler
(password_mgr=None)¶ Handle authentication with the remote host. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported. HTTPBasicAuthHandler will raise aValueError
when presented with a wrong Authentication scheme.
-
class
urllib.request.
ProxyBasicAuthHandler
(password_mgr=None)¶ Handle authentication with the proxy. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported.
-
class
urllib.request.
AbstractDigestAuthHandler
(password_mgr=None)¶ This is a mixin class that helps with HTTP authentication, both to the remote host and to a proxy. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported.
-
class
urllib.request.
HTTPDigestAuthHandler
(password_mgr=None)¶ Handle authentication with the remote host. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported. When both Digest Authentication Handler and Basic Authentication Handler are both added, Digest Authentication is always tried first. If the Digest Authentication returns a 40x response again, it is sent to Basic Authentication handler to Handle. This Handler method will raise aValueError
when presented with an authentication scheme other than Digest or Basic.3.3 版更變: Raise
ValueError
on unsupported Authentication Scheme.
-
class
urllib.request.
ProxyDigestAuthHandler
(password_mgr=None)¶ Handle authentication with the proxy. password_mgr, if given, should be something that is compatible with
HTTPPasswordMgr
; refer to section HTTPPasswordMgr Objects for information on the interface that must be supported.
-
class
urllib.request.
HTTPHandler
¶ A class to handle opening of HTTP URLs.
-
class
urllib.request.
HTTPSHandler
(debuglevel=0, context=None, check_hostname=None)¶ A class to handle opening of HTTPS URLs. context and check_hostname have the same meaning as in
http.client.HTTPSConnection
.3.2 版更變: context and check_hostname were added.
-
class
urllib.request.
FileHandler
¶ Open local files.
-
class
urllib.request.
DataHandler
¶ Open data URLs.
3.4 版新加入.
-
class
urllib.request.
FTPHandler
¶ Open FTP URLs.
-
class
urllib.request.
CacheFTPHandler
¶ Open FTP URLs, keeping a cache of open FTP connections to minimize delays.
-
class
urllib.request.
UnknownHandler
¶ A catch-all class to handle unknown URLs.
-
class
urllib.request.
HTTPErrorProcessor
¶ Process HTTP error responses.
Request Objects¶
The following methods describe Request
's public interface,
and so all may be overridden in subclasses. It also defines several
public attributes that can be used by clients to inspect the parsed
request.
-
Request.
full_url
¶ The original URL passed to the constructor.
3.4 版更變.
Request.full_url is a property with setter, getter and a deleter. Getting
full_url
returns the original request URL with the fragment, if it was present.
-
Request.
type
¶ The URI scheme.
-
Request.
host
¶ The URI authority, typically a host, but may also contain a port separated by a colon.
-
Request.
origin_req_host
¶ The original host for the request, without port.
-
Request.
selector
¶ The URI path. If the
Request
uses a proxy, then selector will be the full URL that is passed to the proxy.
-
Request.
data
¶ The entity body for the request, or
None
if not specified.3.4 版更變: Changing value of
Request.data
now deletes "Content-Length" header if it was previously set or calculated.
-
Request.
unverifiable
¶ boolean, indicates whether the request is unverifiable as defined by RFC 2965.
-
Request.
method
¶ The HTTP request method to use. By default its value is
None
, which means thatget_method()
will do its normal computation of the method to be used. Its value can be set (thus overriding the default computation inget_method()
) either by providing a default value by setting it at the class level in aRequest
subclass, or by passing a value in to theRequest
constructor via the method argument.3.3 版新加入.
3.4 版更變: A default value can now be set in subclasses; previously it could only be set via the constructor argument.
-
Request.
get_method
()¶ Return a string indicating the HTTP request method. If
Request.method
is notNone
, return its value, otherwise return'GET'
ifRequest.data
isNone
, or'POST'
if it's not. This is only meaningful for HTTP requests.3.3 版更變: get_method now looks at the value of
Request.method
.
-
Request.
add_header
(key, val)¶ Add another header to the request. Headers are currently ignored by all handlers except HTTP handlers, where they are added to the list of headers sent to the server. Note that there cannot be more than one header with the same name, and later calls will overwrite previous calls in case the key collides. Currently, this is no loss of HTTP functionality, since all headers which have meaning when used more than once have a (header-specific) way of gaining the same functionality using only one header.
-
Request.
add_unredirected_header
(key, header)¶ Add a header that will not be added to a redirected request.
-
Request.
has_header
(header)¶ Return whether the instance has the named header (checks both regular and unredirected).
-
Request.
remove_header
(header)¶ Remove named header from the request instance (both from regular and unredirected headers).
3.4 版新加入.
-
Request.
get_full_url
()¶ Return the URL given in the constructor.
3.4 版更變.
Returns
Request.full_url
-
Request.
set_proxy
(host, type)¶ Prepare the request by connecting to a proxy server. The host and type will replace those of the instance, and the instance's selector will be the original URL given in the constructor.
-
Request.
get_header
(header_name, default=None)¶ Return the value of the given header. If the header is not present, return the default value.
-
Request.
header_items
()¶ Return a list of tuples (header_name, header_value) of the Request headers.
3.4 版更變: The request methods add_data, has_data, get_data, get_type, get_host, get_selector, get_origin_req_host and is_unverifiable that were deprecated since 3.3 have been removed.
OpenerDirector Objects¶
OpenerDirector
instances have the following methods:
-
OpenerDirector.
add_handler
(handler)¶ handler should be an instance of
BaseHandler
. The following methods are searched, and added to the possible chains (note that HTTP errors are a special case). Note that, in the following, protocol should be replaced with the actual protocol to handle, for examplehttp_response()
would be the HTTP protocol response handler. Also type should be replaced with the actual HTTP code, for examplehttp_error_404()
would handle HTTP 404 errors.<protocol>_open()
--- signal that the handler knows how to open protocol URLs.See
BaseHandler.<protocol>_open()
for more information.http_error_<type>()
--- signal that the handler knows how to handle HTTP errors with HTTP error code type.See
BaseHandler.http_error_<nnn>()
for more information.<protocol>_error()
--- signal that the handler knows how to handle errors from (non-http
) protocol.<protocol>_request()
--- signal that the handler knows how to pre-process protocol requests.See
BaseHandler.<protocol>_request()
for more information.<protocol>_response()
--- signal that the handler knows how to post-process protocol responses.See
BaseHandler.<protocol>_response()
for more information.
-
OpenerDirector.
open
(url, data=None[, timeout])¶ Open the given url (which can be a request object or a string), optionally passing the given data. Arguments, return values and exceptions raised are the same as those of
urlopen()
(which simply calls theopen()
method on the currently installed globalOpenerDirector
). The optional timeout parameter specifies a timeout in seconds for blocking operations like the connection attempt (if not specified, the global default timeout setting will be used). The timeout feature actually works only for HTTP, HTTPS and FTP connections).
-
OpenerDirector.
error
(proto, *args)¶ Handle an error of the given protocol. This will call the registered error handlers for the given protocol with the given arguments (which are protocol specific). The HTTP protocol is a special case which uses the HTTP response code to determine the specific error handler; refer to the
http_error_<type>()
methods of the handler classes.Return values and exceptions raised are the same as those of
urlopen()
.
OpenerDirector objects open URLs in three stages:
The order in which these methods are called within each stage is determined by sorting the handler instances.
Every handler with a method named like
<protocol>_request()
has that method called to pre-process the request.Handlers with a method named like
<protocol>_open()
are called to handle the request. This stage ends when a handler either returns a non-None
value (ie. a response), or raises an exception (usuallyURLError
). Exceptions are allowed to propagate.In fact, the above algorithm is first tried for methods named
default_open()
. If all such methods returnNone
, the algorithm is repeated for methods named like<protocol>_open()
. If all such methods returnNone
, the algorithm is repeated for methods namedunknown_open()
.Note that the implementation of these methods may involve calls of the parent
OpenerDirector
instance'sopen()
anderror()
methods.Every handler with a method named like
<protocol>_response()
has that method called to post-process the response.
BaseHandler Objects¶
BaseHandler
objects provide a couple of methods that are directly
useful, and others that are meant to be used by derived classes. These are
intended for direct use:
-
BaseHandler.
add_parent
(director)¶ Add a director as parent.
-
BaseHandler.
close
()¶ Remove any parents.
The following attribute and methods should only be used by classes derived from
BaseHandler
.
備註
The convention has been adopted that subclasses defining
<protocol>_request()
or <protocol>_response()
methods are named
*Processor
; all others are named *Handler
.
-
BaseHandler.
parent
¶ A valid
OpenerDirector
, which can be used to open using a different protocol, or handle errors.
-
BaseHandler.
default_open
(req)¶ This method is not defined in
BaseHandler
, but subclasses should define it if they want to catch all URLs.This method, if implemented, will be called by the parent
OpenerDirector
. It should return a file-like object as described in the return value of theopen()
ofOpenerDirector
, orNone
. It should raiseURLError
, unless a truly exceptional thing happens (for example,MemoryError
should not be mapped toURLError
).This method will be called before any protocol-specific open method.
-
BaseHandler.<protocol>_open(req)
This method is not defined in
BaseHandler
, but subclasses should define it if they want to handle URLs with the given protocol.This method, if defined, will be called by the parent
OpenerDirector
. Return values should be the same as fordefault_open()
.
-
BaseHandler.
unknown_open
(req)¶ This method is not defined in
BaseHandler
, but subclasses should define it if they want to catch all URLs with no specific registered handler to open it.This method, if implemented, will be called by the
parent
OpenerDirector
. Return values should be the same as fordefault_open()
.
-
BaseHandler.
http_error_default
(req, fp, code, msg, hdrs)¶ This method is not defined in
BaseHandler
, but subclasses should override it if they intend to provide a catch-all for otherwise unhandled HTTP errors. It will be called automatically by theOpenerDirector
getting the error, and should not normally be called in other circumstances.req will be a
Request
object, fp will be a file-like object with the HTTP error body, code will be the three-digit code of the error, msg will be the user-visible explanation of the code and hdrs will be a mapping object with the headers of the error.Return values and exceptions raised should be the same as those of
urlopen()
.
-
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
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
http_error_default()
.
-
BaseHandler.<protocol>_request(req)
This method is not defined in
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
OpenerDirector
. req will be aRequest
object. The return value should be aRequest
object.
-
BaseHandler.<protocol>_response(req, response)
This method is not defined in
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
OpenerDirector
. req will be aRequest
object. response will be an object implementing the same interface as the return value ofurlopen()
. The return value should implement the same interface as the return value ofurlopen()
.
HTTPRedirectHandler Objects¶
備註
Some HTTP redirections require action from this module's client code. If this
is the case, HTTPError
is raised. See RFC 2616 for
details of the precise meanings of the various redirection codes.
An HTTPError
exception raised as a security consideration if the
HTTPRedirectHandler is presented with a redirected URL which is not an HTTP,
HTTPS or FTP URL.
-
HTTPRedirectHandler.
redirect_request
(req, fp, code, msg, hdrs, newurl)¶ Return a
Request
orNone
in response to a redirect. This is called by the default implementations of thehttp_error_30*()
methods when a redirection is received from the server. If a redirection should take place, return a newRequest
to allowhttp_error_30*()
to perform the redirect to newurl. Otherwise, raiseHTTPError
if no other handler should try to handle this URL, or returnNone
if you can't but another handler might.備註
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 aGET
, and the default implementation reproduces this behavior.
-
HTTPRedirectHandler.
http_error_301
(req, fp, code, msg, hdrs)¶ Redirect to the
Location:
orURI:
URL. This method is called by the parentOpenerDirector
when getting an HTTP 'moved permanently' response.
-
HTTPRedirectHandler.
http_error_302
(req, fp, code, msg, hdrs)¶ The same as
http_error_301()
, but called for the 'found' response.
-
HTTPRedirectHandler.
http_error_303
(req, fp, code, msg, hdrs)¶ The same as
http_error_301()
, but called for the 'see other' response.
-
HTTPRedirectHandler.
http_error_307
(req, fp, code, msg, hdrs)¶ The same as
http_error_301()
, but called for the 'temporary redirect' response.
ProxyHandler Objects¶
-
ProxyHandler.<protocol>_open(request)
The
ProxyHandler
will have a method<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 callingrequest.set_proxy()
, and call the next handler in the chain to actually execute the protocol.
HTTPPasswordMgr Objects¶
These methods are available on HTTPPasswordMgr
and
HTTPPasswordMgrWithDefaultRealm
objects.
-
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.
-
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
HTTPPasswordMgrWithDefaultRealm
objects, the realmNone
will be searched if the given realm has no matching user/password.
HTTPPasswordMgrWithPriorAuth Objects¶
This password manager extends HTTPPasswordMgrWithDefaultRealm
to support
tracking URIs for which authentication credentials should always be sent.
-
HTTPPasswordMgrWithPriorAuth.
add_password
(realm, uri, user, passwd, is_authenticated=False)¶ realm, uri, user, passwd are as for
HTTPPasswordMgr.add_password()
. is_authenticated sets the initial value of theis_authenticated
flag for the given URI or list of URIs. If is_authenticated is specified asTrue
, realm is ignored.
-
HTTPPasswordMgr.
find_user_password
(realm, authuri) Same as for
HTTPPasswordMgrWithDefaultRealm
objects
-
HTTPPasswordMgrWithPriorAuth.
update_authenticated
(self, uri, is_authenticated=False)¶ Update the
is_authenticated
flag for the given uri or list of URIs.
-
HTTPPasswordMgrWithPriorAuth.
is_authenticated
(self, authuri)¶ Returns the current state of the
is_authenticated
flag for the given URI.
AbstractBasicAuthHandler Objects¶
-
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)
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).
HTTPBasicAuthHandler Objects¶
-
HTTPBasicAuthHandler.
http_error_401
(req, fp, code, msg, hdrs)¶ Retry the request with authentication information, if available.
ProxyBasicAuthHandler Objects¶
-
ProxyBasicAuthHandler.
http_error_407
(req, fp, code, msg, hdrs)¶ Retry the request with authentication information, if available.
AbstractDigestAuthHandler Objects¶
-
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)
Request
object, and headers should be the error headers.
HTTPDigestAuthHandler Objects¶
-
HTTPDigestAuthHandler.
http_error_401
(req, fp, code, msg, hdrs)¶ Retry the request with authentication information, if available.
ProxyDigestAuthHandler Objects¶
-
ProxyDigestAuthHandler.
http_error_407
(req, fp, code, msg, hdrs)¶ Retry the request with authentication information, if available.
HTTPHandler Objects¶
-
HTTPHandler.
http_open
(req)¶ Send an HTTP request, which can be either GET or POST, depending on
req.has_data()
.
HTTPSHandler Objects¶
-
HTTPSHandler.
https_open
(req)¶ Send an HTTPS request, which can be either GET or POST, depending on
req.has_data()
.
FileHandler Objects¶
DataHandler Objects¶
-
DataHandler.
data_open
(req)¶ Read a data URL. This kind of URL contains the content encoded in the URL itself. The data URL syntax is specified in RFC 2397. This implementation ignores white spaces in base64 encoded data URLs so the URL may be wrapped in whatever source file it comes from. But even though some browsers don't mind about a missing padding at the end of a base64 encoded data URL, this implementation will raise an
ValueError
in that case.
FTPHandler Objects¶
-
FTPHandler.
ftp_open
(req)¶ Open the FTP file indicated by req. The login is always done with empty username and password.
CacheFTPHandler Objects¶
CacheFTPHandler
objects are FTPHandler
objects with the
following additional methods:
-
CacheFTPHandler.
setTimeout
(t)¶ Set timeout of connections to t seconds.
-
CacheFTPHandler.
setMaxConns
(m)¶ Set maximum number of cached connections to m.
UnknownHandler Objects¶
HTTPErrorProcessor Objects¶
-
HTTPErrorProcessor.
http_response
(request, response)¶ 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
http_error_<type>()
handler methods, viaOpenerDirector.error()
. Eventually,HTTPDefaultErrorHandler
will raise anHTTPError
if no other handler handles the error.
-
HTTPErrorProcessor.
https_response
(request, response)¶ Process HTTPS error responses.
The behavior is same as
http_response()
.
Examples¶
In addition to the examples below, more examples are given in 如何使用urllib套件取得網路資源.
This example gets the python.org main page and displays the first 300 bytes of it.
>>> import urllib.request
>>> with urllib.request.urlopen('http://www.python.org/') as f:
... print(f.read(300))
...
b'<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">\n\n\n<html
xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">\n\n<head>\n
<meta http-equiv="content-type" content="text/html; charset=utf-8" />\n
<title>Python Programming '
Note that urlopen returns a bytes object. This is because there is no way for urlopen to automatically determine the encoding of the byte stream it receives from the HTTP server. In general, a program will decode the returned bytes object to string once it determines or guesses the appropriate encoding.
The following W3C document, https://www.w3.org/International/O-charset, lists the various ways in which an (X)HTML or an XML document could have specified its encoding information.
As the python.org website uses utf-8 encoding as specified in its meta tag, we will use the same for decoding the bytes object.
>>> with urllib.request.urlopen('http://www.python.org/') as f:
... print(f.read(100).decode('utf-8'))
...
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtm
It is also possible to achieve the same result without using the context manager approach.
>>> import urllib.request
>>> f = urllib.request.urlopen('http://www.python.org/')
>>> print(f.read(100).decode('utf-8'))
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtm
In the following example, 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 urllib.request
>>> req = urllib.request.Request(url='https://localhost/cgi-bin/test.cgi',
... data=b'This data is passed to stdin of the CGI')
>>> with urllib.request.urlopen(req) as f:
... print(f.read().decode('utf-8'))
...
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)
Here is an example of doing a PUT
request using Request
:
import urllib.request
DATA = b'some data'
req = urllib.request.Request(url='http://localhost:8080', data=DATA,method='PUT')
with urllib.request.urlopen(req) as f:
pass
print(f.status)
print(f.reason)
Use of Basic HTTP Authentication:
import urllib.request
# Create an OpenerDirector with support for Basic HTTP Authentication...
auth_handler = urllib.request.HTTPBasicAuthHandler()
auth_handler.add_password(realm='PDQ Application',
uri='https://mahler:8092/site-updates.py',
user='klem',
passwd='kadidd!ehopper')
opener = urllib.request.build_opener(auth_handler)
# ...and install it globally so it can be used with urlopen.
urllib.request.install_opener(opener)
urllib.request.urlopen('http://www.example.com/login.html')
build_opener()
provides many handlers by default, including a
ProxyHandler
. By default, ProxyHandler
uses the environment
variables named <scheme>_proxy
, where <scheme>
is the URL scheme
involved. For example, the http_proxy
environment variable is read to
obtain the HTTP proxy's URL.
This example replaces the default ProxyHandler
with one that uses
programmatically-supplied proxy URLs, and adds proxy authorization support with
ProxyBasicAuthHandler
.
proxy_handler = urllib.request.ProxyHandler({'http': 'http://www.example.com:3128/'})
proxy_auth_handler = urllib.request.ProxyBasicAuthHandler()
proxy_auth_handler.add_password('realm', 'host', 'username', 'password')
opener = urllib.request.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 Request
constructor, or:
import urllib.request
req = urllib.request.Request('http://www.example.com/')
req.add_header('Referer', 'http://www.python.org/')
# Customize the default User-Agent header value:
req.add_header('User-Agent', 'urllib-example/0.1 (Contact: . . .)')
r = urllib.request.urlopen(req)
OpenerDirector
automatically adds a User-Agent header to
every Request
. To change this:
import urllib.request
opener = urllib.request.build_opener()
opener.addheaders = [('User-agent', 'Mozilla/5.0')]
opener.open('http://www.example.com/')
Also, remember that a few standard headers (Content-Length,
Content-Type and Host)
are added when the Request
is passed to urlopen()
(or
OpenerDirector.open()
).
Here is an example session that uses the GET
method to retrieve a URL
containing parameters:
>>> import urllib.request
>>> import urllib.parse
>>> params = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
>>> url = "http://www.musi-cal.com/cgi-bin/query?%s" % params
>>> with urllib.request.urlopen(url) as f:
... print(f.read().decode('utf-8'))
...
The following example uses the POST
method instead. Note that params output
from urlencode is encoded to bytes before it is sent to urlopen as data:
>>> import urllib.request
>>> import urllib.parse
>>> data = urllib.parse.urlencode({'spam': 1, 'eggs': 2, 'bacon': 0})
>>> data = data.encode('ascii')
>>> with urllib.request.urlopen("http://requestb.in/xrbl82xr", data) as f:
... print(f.read().decode('utf-8'))
...
The following example uses an explicitly specified HTTP proxy, overriding environment settings:
>>> import urllib.request
>>> proxies = {'http': 'http://proxy.example.com:8080/'}
>>> opener = urllib.request.FancyURLopener(proxies)
>>> with opener.open("http://www.python.org") as f:
... f.read().decode('utf-8')
...
The following example uses no proxies at all, overriding environment settings:
>>> import urllib.request
>>> opener = urllib.request.FancyURLopener({})
>>> with opener.open("http://www.python.org/") as f:
... f.read().decode('utf-8')
...
Legacy interface¶
The following functions and classes are ported from the Python 2 module
urllib
(as opposed to urllib2
). They might become deprecated at
some point in the future.
-
urllib.request.
urlretrieve
(url, filename=None, reporthook=None, data=None)¶ Copy a network object denoted by a URL to a local file. If the URL points to a local file, the object will not be copied unless filename is supplied. Return a tuple
(filename, headers)
where filename is the local file name under which the object can be found, and headers is whatever theinfo()
method of the object returned byurlopen()
returned (for a remote object). Exceptions are the same as forurlopen()
.The second argument, if present, specifies the file location to copy to (if absent, the location will be a tempfile with a generated name). The third argument, if present, is a callable that will be called once on establishment of the network connection and once after each block read thereafter. The callable will be passed three arguments; a count of blocks transferred so far, a block size in bytes, and the total size of the file. The third argument may be
-1
on older FTP servers which do not return a file size in response to a retrieval request.The following example illustrates the most common usage scenario:
>>> import urllib.request >>> local_filename, headers = urllib.request.urlretrieve('http://python.org/') >>> html = open(local_filename) >>> html.close()
If the url uses the
http:
scheme identifier, the optional data argument may be given to specify aPOST
request (normally the request type isGET
). The data argument must be a bytes object in standard application/x-www-form-urlencoded format; see theurllib.parse.urlencode()
function.urlretrieve()
will raiseContentTooShortError
when it detects that the amount of data available was less than the expected amount (which is the size reported by a Content-Length header). This can occur, for example, when the download is interrupted.The Content-Length is treated as a lower bound: if there's more data to read, urlretrieve reads more data, but if less data is available, it raises the exception.
You can still retrieve the downloaded data in this case, it is stored in the
content
attribute of the exception instance.If no Content-Length header was supplied, urlretrieve can not check the size of the data it has downloaded, and just returns it. In this case you just have to assume that the download was successful.
-
urllib.request.
urlcleanup
()¶ Cleans up temporary files that may have been left behind by previous calls to
urlretrieve()
.
-
class
urllib.request.
URLopener
(proxies=None, **x509)¶ 3.3 版後已棄用.
Base class for opening and reading URLs. Unless you need to support opening objects using schemes other than
http:
,ftp:
, orfile:
, you probably want to useFancyURLopener
.By default, the
URLopener
class sends a User-Agent header ofurllib/VVV
, where VVV is theurllib
version number. Applications can define their own User-Agent header by subclassingURLopener
orFancyURLopener
and setting the class attributeversion
to an appropriate string value in the subclass definition.The optional proxies parameter should be a dictionary mapping scheme names to proxy URLs, where an empty dictionary turns proxies off completely. Its default value is
None
, in which case environmental proxy settings will be used if present, as discussed in the definition ofurlopen()
, above.Additional keyword parameters, collected in x509, may be used for authentication of the client when using the
https:
scheme. The keywords key_file and cert_file are supported to provide an SSL key and certificate; both are needed to support client authentication.URLopener
objects will raise anOSError
exception if the server returns an error code.-
open
(fullurl, data=None)¶ Open fullurl using the appropriate protocol. This method sets up cache and proxy information, then calls the appropriate open method with its input arguments. If the scheme is not recognized,
open_unknown()
is called. The data argument has the same meaning as the data argument ofurlopen()
.This method always quotes fullurl using
quote()
.
-
open_unknown
(fullurl, data=None)¶ Overridable interface to open unknown URL types.
-
retrieve
(url, filename=None, reporthook=None, data=None)¶ Retrieves the contents of url and places it in filename. The return value is a tuple consisting of a local filename and either an
email.message.Message
object containing the response headers (for remote URLs) orNone
(for local URLs). The caller must then open and read the contents of filename. If filename is not given and the URL refers to a local file, the input filename is returned. If the URL is non-local and filename is not given, the filename is the output oftempfile.mktemp()
with a suffix that matches the suffix of the last path component of the input URL. If reporthook is given, it must be a function accepting three numeric parameters: A chunk number, the maximum size chunks are read in and the total size of the download (-1 if unknown). It will be called once at the start and after each chunk of data is read from the network. reporthook is ignored for local URLs.If the url uses the
http:
scheme identifier, the optional data argument may be given to specify aPOST
request (normally the request type isGET
). The data argument must in standard application/x-www-form-urlencoded format; see theurllib.parse.urlencode()
function.
-
-
class
urllib.request.
FancyURLopener
(...)¶ 3.3 版後已棄用.
FancyURLopener
subclassesURLopener
providing default handling for the following HTTP response codes: 301, 302, 303, 307 and 401. For the 30x response codes listed above, the Location header is used to fetch the actual URL. For 401 response codes (authentication required), basic HTTP authentication is performed. For the 30x response codes, recursion is bounded by the value of the maxtries attribute, which defaults to 10.For all other response codes, the method
http_error_default()
is called which you can override in subclasses to handle the error appropriately.備註
According to the letter of RFC 2616, 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
urllib
reproduces this behaviour.The parameters to the constructor are the same as those for
URLopener
.備註
When performing basic authentication, a
FancyURLopener
instance calls itsprompt_user_passwd()
method. The default implementation asks the users for the required information on the controlling terminal. A subclass may override this method to support more appropriate behavior if needed.The
FancyURLopener
class offers one additional method that should be overloaded to provide the appropriate behavior:-
prompt_user_passwd
(host, realm)¶ Return information needed to authenticate the user at the given host in the specified security realm. The return value should be a tuple,
(user, password)
, which can be used for basic authentication.The implementation prompts for this information on the terminal; an application should override this method to use an appropriate interaction model in the local environment.
-
urllib.request
Restrictions¶
Currently, only the following protocols are supported: HTTP (versions 0.9 and 1.0), FTP, local files, and data URLs.
3.4 版更變: Added support for data URLs.
The caching feature of
urlretrieve()
has been disabled until someone finds the time to hack proper processing of Expiration time headers.There should be a function to query whether a particular URL is in the cache.
For backward compatibility, if a URL appears to point to a local file but the file can't be opened, the URL is re-interpreted using the FTP protocol. This can sometimes cause confusing error messages.
The
urlopen()
andurlretrieve()
functions can cause arbitrarily long delays while waiting for a network connection to be set up. This means that it is difficult to build an interactive Web client using these functions without using threads.The data returned by
urlopen()
orurlretrieve()
is the raw data returned by the server. This may be binary data (such as an image), plain text or (for example) HTML. The HTTP protocol provides type information in the reply header, which can be inspected by looking at the Content-Type header. If the returned data is HTML, you can use the modulehtml.parser
to parse it.The code handling the FTP protocol cannot differentiate between a file and a directory. This can lead to unexpected behavior when attempting to read a URL that points to a file that is not accessible. If the URL ends in a
/
, it is assumed to refer to a directory and will be handled accordingly. But if an attempt to read a file leads to a 550 error (meaning the URL cannot be found or is not accessible, often for permission reasons), then the path is treated as a directory in order to handle the case when a directory is specified by a URL but the trailing/
has been left off. This can cause misleading results when you try to fetch a file whose read permissions make it inaccessible; the FTP code will try to read it, fail with a 550 error, and then perform a directory listing for the unreadable file. If fine-grained control is needed, consider using theftplib
module, subclassingFancyURLopener
, or changing _urlopener to meet your needs.
urllib.response
--- Response classes used by urllib¶
The urllib.response
module defines functions and classes which define a
minimal file like interface, including read()
and readline()
. The
typical response object is an addinfourl instance, which defines an info()
method and that returns headers and a geturl()
method that returns the url.
Functions defined by this module are used internally by the
urllib.request
module.