21.6. `urllib.request` — 用于打开 URL 的可扩展库 ¶

urllib.request 模块定义有助于在复杂环境打开 URL (主要是 HTTP) 的函数和类 — 基本和摘要身份验证、重定向、Cookie 等。

另请参阅

Requests 包推荐为更高级别的 HTTP 客户端接口。

urllib.request 模块定义了下列函数：

urllib.request. urlopen ( url , data=None , [ timeout , ] * , cafile=None , capath=None , cadefault=False , context=None ) ¶

打开 URL url ，其可以是字符串或 Request 对象。

data 必须是指定要被发送给服务器的额外数据的对象，或 None 若不需要这样的数据。见 Request 了解细节。

urllib.request 模块使用 HTTP/1.1 并包括 Connection:close HTTP 头在其 HTTP 请求中。

可选 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.

若 context 被指定，它必须是 ssl.SSLContext 实例 (描述各种 SSL 选项)。见 HTTPSConnection 了解更多细节。

可选 cafile and capath 参数为 HTTPS 请求指定一组受信任的 CA 证书。 cafile 应该指向包含一捆 CA 证书的单个文件，而 capath should point to a directory of hashed certificate files. More information can be found in ssl.SSLContext.load_verify_locations() .

cadefault 参数被忽略。

该函数总是返回对象，其能作为上下文管理器并具有如下方法

geturl() — return the URL of the resource retrieved, commonly used to determine if a redirect was followed
info() — return the meta-information of the page, such as headers, in the form of an email.message_from_string() 实例 (见快速参考 HTTP 头 )
getcode() – 返回响应的 HTTP 状态代码。

对于 HTTP 和 HTTPS URL，此函数返回 http.client.HTTPResponse 稍微修改对象。除上述 3 新方法外，msg 属性包含的信息如同 reason 属性 — 由服务器返回的原因短语 — 而不是在文档编制中指定的响应 Header 头为 HTTPResponse .

对于 FTP、文件、数据 URL 及请求明确被处理通过传统 URLopener and FancyURLopener 类，此函数返回 urllib.response.addinfourl 对象。

引发 URLError 在协议错误时。

注意， None 可能被返回，若没有处理程序处理请求 (虽然默认安装了全局 OpenerDirector 使用 UnknownHandler 以确保这从不发生)。

此外，若检测到代理设置 (例如，当 *_proxy 环境变量像 http_proxy 有设置)， ProxyHandler ProxyHandler 是默认安装的，并确保透过代理处理请求。

传统 urllib.urlopen 函数从 Python 2.6 及更早版本起已被放弃； urllib.request.urlopen() 相当于旧 urllib2.urlopen 。处理代理是把字典参数传递给 urllib.urlopen ，可以获得通过使用 ProxyHandler 对象。

3.2 版改变： cafile and capath 被添加。

3.2 版改变：现在支持 HTTPS 虚拟主机，若可能的话 (也就是说，若 ssl.HAS_SNI 为 True)。

3.2 版新增： data 可以是可迭代对象。

3.3 版改变： cadefault 被添加。

3.4.3 版改变： context 被添加。

从 3.6 版起弃用： cafile , capath and cadefault 被弃用代之 context 。请使用 ssl.SSLContext.load_cert_chain() 代替，或让 ssl.create_default_context() 为您选择系统的受信任 CA 证书。

urllib.request. install_opener ( opener ) ¶: 安装 OpenerDirector instance as the default global opener. Installing an opener is only necessary if you want urlopen to use that opener; otherwise, simply call OpenerDirector.open() 而不是 urlopen() . The code does not check for a real OpenerDirector , and any class with the appropriate interface will work.

urllib.request. build_opener ( [ handler , ... ] ) ¶

返回 OpenerDirector instance, which chains the handlers in the order given. handler s can be either instances of BaseHandler , or subclasses of BaseHandler (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 handler s, unless the handler s contain them, instances of them or subclasses of them: ProxyHandler (if proxy settings are detected), UnknownHandler , HTTPHandler , HTTPDefaultErrorHandler , HTTPRedirectHandler , FTPHandler , FileHandler , HTTPErrorProcessor .

若 Python 安装有 SSL 支持 (即：若 ssl 模块可以被导入)， HTTPSHandler will also be added.

A BaseHandler subclass may also change its handler_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() 函数。

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.

注意

若环境变量 REQUEST_METHOD is set, which usually indicates your script is running in a CGI environment, the environment variable HTTP_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 use ProxyHandler explicitly, or make sure the variable name is in lowercase (or at least the _proxy 后缀)。

提供了下列类：

class urllib.request. Request ( url , data=None , headers={} , origin_req_host=None , unverifiable=False , method=None ) ¶

此类是 URL 请求的抽象。

url 应是包含有效 URL 的字符串。

data 必须是指定要发送给服务器的额外数据的对象，或 None 若不需要这样的数据。目前，仅 HTTP 请求使用 data 。支持对象类型包括：bytes、类文件对象和可迭代对象。如果 Content-Length nor Transfer-Encoding Header 头字段未提供， HTTPHandler 将设置这些头根据 data 类型。 Content-Length 将被用于发送 bytes 对象，而 Transfer-Encoding: chunked 如指定在 RFC 7230 ，章节 3.3.1 将被用于发送文件及其它可迭代。

对于 HTTP POST (张贴) 请求方法， data 应该是缓冲，采用标准 application/x-www-form-urlencoded 格式。 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 参数。

headers 应该字典，且会被视为采用每键值作为自变量去调用 add_header() 。这经常被用于欺骗 User-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" ，而 urllib 的默认用户代理字符串是 "Python-urllib/2.6" (在 Python 2.6)。

适当 Content-Type 头应该包括，若 data 自变量存在。若此 Header 头未提供且 data 不是 None， Content-Type: application/x-www-form-urlencoded 将被添加作为默认。

最后 2 自变量仅对正确处理第 3 方 HTTP Cookie 感兴趣：

origin_req_host 应该是原始事务的请求主机，定义由 RFC 2965 。它默认为 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 应该指示请求是否不可验证，定义由 RFC 2965 。它默认为 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.

方法应该是指示将使用的 HTTP 请求方法的字符串 (如 'HEAD' )。若提供，其值被存储在 方法 属性且被使用通过 get_method() 。默认为 'GET' if data is None or 'POST' 否则。子类可能指示不同的默认方法，通过设置 方法 类本身属性。

注意

请求不会按预期工作，若数据对象无法多次交付其内容 (如：仅可以一次产生内容的文件或可迭代) 和重试请求为 HTTP 重定向或身份验证。 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 版改变： Request.method 自变量被添加到 Request 类。

3.4 版改变：默认 Request.method 可能被指示在类级别。

3.6 版改变：不引发错误若 Content-Length 未提供且 data 为 None 或 bytes 对象。代之，回退到使用分块传输编码。

class urllib.request. OpenerDirector ¶: OpenerDirector 类打开 URL 凭借 BaseHandler 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 异常。

class urllib.request. HTTPRedirectHandler ¶: 处理重定向的类。

class urllib.request. HTTPCookieProcessor ( cookiejar=None ) ¶: 处理 HTTP Cookie 的类。

class urllib.request. ProxyHandler ( proxies=None ) ¶

促使请求透过代理进行。若 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.

要禁用自动检测代理，传递空字典。

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 example cern.ch,ncsa.uiuc.edu,some.host:8080 .

注意

HTTP_PROXY 会被忽略若变量 REQUEST_METHOD 被设置；见文档编制 getproxies() .

class urllib.request. HTTPPasswordMgr ¶: 保持数据库的 (realm, uri) -> (user, password) 映射。

class urllib.request. HTTPPasswordMgrWithDefaultRealm ¶: 保持数据库的 (realm, uri) -> (user, password) mappings. A realm of None 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 of uri -> is_authenticated mappings. Can be used by a BasicAuth handler to determine when to send authentication credentials immediately instead of waiting for a 401 response first.

3.5 版新增。

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 对象 for information on the interface that must be supported. If passwd_mgr also provides is_authenticated and update_authenticated methods (see HTTPPasswordMgrWithPriorAuth Objects ), then the handler will use the is_authenticated result for a given URI to determine whether or not to send authentication credentials with the request. If is_authenticated 返回 True for the URI, credentials are sent. If is_authenticated is False , credentials are not sent, and then if a 401 response is received the request is re-sent with the authentication credentials. If authentication succeeds, update_authenticated is called to set is_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 版新增：添加 is_authenticated 支持。

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 对象 for information on the interface that must be supported. HTTPBasicAuthHandler will raise a ValueError 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 对象 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 对象 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 对象 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 a ValueError when presented with an authentication scheme other than Digest or Basic.

3.3 版改变：引发 ValueError 当身份验证方案不被支持时。

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 对象 for information on the interface that must be supported.

class urllib.request. HTTPHandler ¶: 处理打开 HTTP URL 的类。

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 版改变： context and check_hostname 被添加。

class urllib.request. FileHandler ¶: 打开本地文件。

class urllib.request. DataHandler ¶: 打开数据 URL。

3.4 版新增。

class urllib.request. FTPHandler ¶: 打开 FTP URL。

class urllib.request. CacheFTPHandler ¶: 打开 FTP URL，保持打开 FTP 连接的缓存以最小化延迟。

class urllib.request. UnknownHandler ¶: A catch-all class to handle unknown URLs.

class urllib.request. HTTPErrorProcessor ¶: 处理 HTTP 错误响应。

21.6.1. 请求对象 ¶

以下方法描述 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 ¶

被传递给构造函数的原始 URL。

3.4 版改变。

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 ¶: URI 方案。

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 ¶: URI 路径。若 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 版改变： 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. 方法 ¶: The HTTP request method to use. By default its value is None , which means that get_method() will do its normal computation of the method to be used. Its value can be set (thus overriding the default computation in get_method() ) either by providing a default value by setting it at the class level in a Request subclass, or by passing a value in to the Request constructor via the 方法自变量。

3.3 版新增。

3.4 版改变： 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 不是 None , return its value, otherwise return 'GET' if Request.data is None ，或 'POST' if it’s not. This is only meaningful for HTTP requests.

3.3 版改变： 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 ) ¶: 添加不会被添加到重定向请求的 Header 头。

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 版新增。

Request. get_full_url ( ) ¶

返回在构造函数中给定的 URL。

3.4 版改变。

返回 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 版改变： 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.

21.6.2. OpenerDirector 对象 ¶

OpenerDirector 实例具有下列方法：

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).

protocol_open() — signal that the handler knows how to open protocol URLs.
http_error_type() — signal that the handler knows how to handle HTTP errors with HTTP error code type .
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.
protocol_response() — signal that the handler knows how to post-process protocol responses.

OpenerDirector. open ( url , data=None [ , timeout ] ) ¶: 打开给定 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 the open() method on the currently installed global OpenerDirector ). 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_*() methods of the handler classes.

Return values and exceptions raised are the same as those of urlopen() .

OpenerDirector 对象按 3 阶段打开 URL：

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 (usually URLError ). Exceptions are allowed to propagate.

In fact, the above algorithm is first tried for methods named default_open() . If all such methods return None , the algorithm is repeated for methods named like protocol_open() . If all such methods return None , the algorithm is repeated for methods named unknown_open() .

Note that the implementation of these methods may involve calls of the parent OpenerDirector instance’s open() and error() 方法。
Every handler with a method named like protocol_response() has that method called to post-process the response.

21.6.3. BaseHandler 对象 ¶

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 ( ) ¶: 移除任何父级。

The following attribute and methods should only be used by classes derived from BaseHandler .

注意

The convention has been adopted that subclasses defining protocol_request() or protocol_response() methods are named *Processor ; all others are named *Handler .

BaseHandler. parent ¶: 有效 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 the open() of OpenerDirector ，或 None . It should raise URLError , unless a truly exceptional thing happens (for example, MemoryError should not be mapped to URLError ).

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 for default_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 for default_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 the OpenerDirector getting the error, and should not normally be called in other circumstances.

req will be a Request 对象， 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 a Request object. The return value should be a Request 对象。

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 a Request 对象。 response will be an object implementing the same interface as the return value of urlopen() . The return value should implement the same interface as the return value of urlopen() .

21.6.4. HTTPRedirectHandler 对象 ¶

注意

Some HTTP redirections require action from this module’s client code. If this is the case, HTTPError 被引发。见 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 ) ¶: 返回 Request or None in response to a redirect. This is called by the default implementations of the http_error_30*() methods when a redirection is received from the server. If a redirection should take place, return a new Request to allow http_error_30*() to perform the redirect to newurl . Otherwise, raise HTTPError if no other handler should try to handle this URL, or return None if you can’t but another handler might.

注意

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.

HTTPRedirectHandler. http_error_301 ( req , fp , code , msg , hdrs ) ¶: 重定向到 Location: or URI: URL. This method is called by the parent OpenerDirector when getting an HTTP ‘moved permanently’ response.

HTTPRedirectHandler. http_error_302 ( req , fp , code , msg , hdrs ) ¶: 如同 http_error_301() , but called for the ‘found’ response.

HTTPRedirectHandler. http_error_303 ( req , fp , code , msg , hdrs ) ¶: 如同 http_error_301() , but called for the ‘see other’ response.

HTTPRedirectHandler. http_error_307 ( req , fp , code , msg , hdrs ) ¶: 如同 http_error_301() , but called for the ‘temporary redirect’ response.

21.6.5. HTTPCookieProcessor 对象 ¶

HTTPCookieProcessor 实例有一属性：

HTTPCookieProcessor. cookiejar ¶: http.cookiejar.CookieJar 在其中存储 Cookie。

21.6.6. ProxyHandler 对象 ¶

ProxyHandler. protocol_open ( request ): 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 calling request.set_proxy() , and call the next handler in the chain to actually execute the protocol.

21.6.7. HTTPPasswordMgr 对象 ¶

这些方法可用于 HTTPPasswordMgr and HTTPPasswordMgrWithDefaultRealm 对象。

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 对象，realm None will be searched if the given realm has no matching user/password.

21.6.8. HTTPPasswordMgrWithPriorAuth 对象 ¶

此口令管理器扩展 HTTPPasswordMgrWithDefaultRealm 以支持跟踪其身份验证证书始终会被发送的 URI。

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 the is_authenticated flag for the given URI or list of URIs. If is_authenticated is specified as True , realm 被忽略。

HTTPPasswordMgr. find_user_password ( realm , authuri ): 如同 HTTPPasswordMgrWithDefaultRealm 对象

HTTPPasswordMgrWithPriorAuth. update_authenticated ( self , uri , is_authenticated=False ) ¶: 更新 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.

21.6.9. AbstractBasicAuthHandler 对象 ¶

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).

21.6.10. HTTPBasicAuthHandler 对象 ¶

HTTPBasicAuthHandler. http_error_401 ( req , fp , code , msg , hdrs ) ¶: Retry the request with authentication information, if available.

21.6.11. ProxyBasicAuthHandler 对象 ¶

ProxyBasicAuthHandler. http_error_407 ( req , fp , code , msg , hdrs ) ¶: Retry the request with authentication information, if available.

21.6.12. AbstractDigestAuthHandler 对象 ¶

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.

21.6.13. HTTPDigestAuthHandler 对象 ¶

HTTPDigestAuthHandler. http_error_401 ( req , fp , code , msg , hdrs ) ¶: Retry the request with authentication information, if available.

21.6.14. ProxyDigestAuthHandler 对象 ¶

ProxyDigestAuthHandler. http_error_407 ( req , fp , code , msg , hdrs ) ¶: Retry the request with authentication information, if available.

21.6.15. HTTPHandler 对象 ¶

HTTPHandler. http_open ( req ) ¶: Send an HTTP request, which can be either GET or POST, depending on req.has_data() .

21.6.16. HTTPSHandler 对象 ¶

HTTPSHandler. https_open ( req ) ¶: Send an HTTPS request, which can be either GET or POST, depending on req.has_data() .

21.6.17. FileHandler 对象 ¶

FileHandler. file_open ( req ) ¶: Open the file locally, if there is no host name, or the host name is 'localhost' .

3.2 版改变： This method is applicable only for local hostnames. When a remote hostname is given, an URLError 被引发。

21.6.18. DataHandler 对象 ¶

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.

21.6.19. FTPHandler 对象 ¶

FTPHandler. ftp_open ( req ) ¶: Open the FTP file indicated by req . The login is always done with empty username and password.

21.6.20. CacheFTPHandler 对象 ¶

CacheFTPHandler 对象是 FTPHandler 对象，具有以下额外方法：

CacheFTPHandler. setTimeout ( t ) ¶: 把连接超时设为 t 秒。

CacheFTPHandler. setMaxConns ( m ) ¶: 把缓存的最大连接数设为 m .

21.6.21. UnknownHandler 对象 ¶

UnknownHandler. unknown_open ( ) ¶: 引发 URLError 异常。

21.6.22. HTTPErrorProcessor 对象 ¶

HTTPErrorProcessor. http_response ( request , response ) ¶

处理 HTTP 错误响应。

对于 200 错误代码，响应对象被立即返回。

For non-200 error codes, this simply passes the job on to the protocol_error_code() handler methods, via OpenerDirector.error() . Eventually, HTTPDefaultErrorHandler will raise an HTTPError if no other handler handles the error.

HTTPErrorProcessor. https_response ( request , response ) ¶

处理 HTTPS 错误响应。

行为如同 http_response() .

21.6.23. 范例 ¶

除以下范例外，更多范例给出于如何使用 urllib 包抓取互联网资源 .

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 上下文管理器 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 ，其中 <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')
								
							

添加 HTTP 头：

使用 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 会被传递给 urlopen() (或 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'))
...
								
							

以下范例使用 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')
...
								
							

21.6.24. 传统接口 ¶

以下函数和类移植自 Python 2 模块 urllib (而不是 urllib2 )。它们可能在未来的某个时候被弃用。

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 the info() method of the object returned by urlopen() returned (for a remote object). Exceptions are the same as for urlopen() .

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()
										
									

若 url 使用 http: scheme identifier, the optional data argument may be given to specify a POST request (normally the request type is GET ). The data argument must be a bytes object in standard application/x-www-form-urlencoded format; see the urllib.parse.urlencode() 函数。

urlretrieve() 会引发 ContentTooShortError 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.

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.

若无 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 ) ¶

从 3.3 版起弃用。

Base class for opening and reading URLs. Unless you need to support opening objects using schemes other than http: , ftp: ，或 文件： , you probably want to use FancyURLopener .

默认情况下， URLopener class sends a User-Agent header of urllib/VVV ，其中 VVV 是 urllib version number. Applications can define their own User-Agent header by subclassing URLopener or FancyURLopener and setting the class attribute version to an appropriate string value in the subclass definition.

可选 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 of urlopen() , 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 an OSError exception if the server returns an error code.

open ( fullurl , data=None ) ¶: 打开 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() 被调用。 data argument has the same meaning as the data argument of urlopen() .

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) or None (for local URLs). The caller must then open and read the contents of filename 。若 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 of tempfile.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.

若 url 使用 http: scheme identifier, the optional data argument may be given to specify a POST request (normally the request type is GET ). The data argument must in standard application/x-www-form-urlencoded format; see the urllib.parse.urlencode() 函数。

version ¶: Variable that specifies the user agent of the opener object. To get urllib to tell servers that it is a particular user agent, set this in a subclass as a class variable or in the constructor before calling the base constructor.

class urllib.request. FancyURLopener ( ... ) ¶

从 3.3 版起弃用。

FancyURLopener subclasses URLopener providing default handling for the following HTTP response codes: 301, 302, 303, 307 and 401. For the 30x response codes listed above, the 定位 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.

注意

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 .

注意

When performing basic authentication, a FancyURLopener instance calls its prompt_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.

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.

21.6.25. `urllib.request` 限定 ¶

目前，只支持以下协议：HTTP (第 0.9 和 1.0 版)、FTP、本地文件及数据 URL。

3.4 版改变：添加支持数据 URL。
缓存特征的 urlretrieve() 已被禁用，直到有人找到时间骇客 Expiration (过期) 时间头的适当处理。
应该有函数去查询特定 URL 是否在缓存中。
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.
urlopen() and urlretrieve() 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.
返回的数据通过 urlopen() or urlretrieve() 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 头。若返回的数据是 HTML，可以使用模块 html.parser 去剖析它。
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 the ftplib 模块，子类化 FancyURLopener ，或更改 _urlopener 以满足需要。

21.7. `urllib.response` — 用于 urllib 的响应类 ¶

urllib.response 模块定义的函数和类 (定义最小像文件接口)，包括 read() and readline() 。典型的响应对象是 addinfourl 实例，其定义 info() 方法以返回 Header 头及 geturl() method that returns the url. Functions defined by this module are used internally by the urllib.request 模块。

21.6. `urllib.request` — 用于打开 URL 的可扩展库 ¶

21.6.1. 请求对象 ¶

21.6.2. OpenerDirector 对象 ¶

21.6.3. BaseHandler 对象 ¶

21.6.4. HTTPRedirectHandler 对象 ¶

21.6.5. HTTPCookieProcessor 对象 ¶

21.6.6. ProxyHandler 对象 ¶

21.6.7. HTTPPasswordMgr 对象 ¶

21.6.8. HTTPPasswordMgrWithPriorAuth 对象 ¶

21.6.9. AbstractBasicAuthHandler 对象 ¶

21.6.10. HTTPBasicAuthHandler 对象 ¶

21.6.11. ProxyBasicAuthHandler 对象 ¶

21.6.12. AbstractDigestAuthHandler 对象 ¶

21.6.13. HTTPDigestAuthHandler 对象 ¶

21.6.14. ProxyDigestAuthHandler 对象 ¶

21.6.15. HTTPHandler 对象 ¶

21.6.16. HTTPSHandler 对象 ¶

21.6.17. FileHandler 对象 ¶

21.6.18. DataHandler 对象 ¶

21.6.19. FTPHandler 对象 ¶

21.6.20. CacheFTPHandler 对象 ¶

21.6.21. UnknownHandler 对象 ¶

21.6.22. HTTPErrorProcessor 对象 ¶

21.6.23. 范例 ¶

21.6.24. 传统接口 ¶

21.6.25. `urllib.request` 限定 ¶

21.7. `urllib.response` — 用于 urllib 的响应类 ¶

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21.6. urllib.request — 用于打开 URL 的可扩展库 ¶

21.6.1. 请求对象 ¶

21.6.2. OpenerDirector 对象 ¶

21.6.3. BaseHandler 对象 ¶

21.6.4. HTTPRedirectHandler 对象 ¶

21.6.5. HTTPCookieProcessor 对象 ¶

21.6.6. ProxyHandler 对象 ¶

21.6.7. HTTPPasswordMgr 对象 ¶

21.6.8. HTTPPasswordMgrWithPriorAuth 对象 ¶

21.6.9. AbstractBasicAuthHandler 对象 ¶

21.6.10. HTTPBasicAuthHandler 对象 ¶

21.6.11. ProxyBasicAuthHandler 对象 ¶

21.6.12. AbstractDigestAuthHandler 对象 ¶

21.6.13. HTTPDigestAuthHandler 对象 ¶

21.6.14. ProxyDigestAuthHandler 对象 ¶

21.6.15. HTTPHandler 对象 ¶

21.6.16. HTTPSHandler 对象 ¶

21.6.17. FileHandler 对象 ¶

21.6.18. DataHandler 对象 ¶

21.6.19. FTPHandler 对象 ¶

21.6.20. CacheFTPHandler 对象 ¶

21.6.21. UnknownHandler 对象 ¶

21.6.22. HTTPErrorProcessor 对象 ¶

21.6.23. 范例 ¶

21.6.24. 传统接口 ¶

21.6.25. urllib.request 限定 ¶

21.7. urllib.response — 用于 urllib 的响应类 ¶

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21.6. `urllib.request` — 用于打开 URL 的可扩展库 ¶

21.6.25. `urllib.request` 限定 ¶

21.7. `urllib.response` — 用于 urllib 的响应类 ¶