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urllib.parse — 将 URL 剖析成组件

源代码： Lib/urllib/parse.py

此模块定义的标准接口能将 URL (统一资源定位符) 字符串分解成组件 (编址方案、网络位置、路径等)，将组件组合回 URL 字符串，及将给定基 URL 的相对 URL 转换成绝对 URL。

模块被设计成匹配互联网 RFC 相对 URL (统一资源定位符)。它支持下列 URL 方案： file , ftp , gopher , hdl , http , https , imap , mailto , mms , news , nntp , prospero , rsync , rtsp , rtspu , sftp , shttp , sip , sips , snews , svn , svn+ssh , telnet , wais , ws , wss .

The urllib.parse 模块定义的函数分为 2 大类：URL 剖析和 URL 引用。这些将详细涵盖在下列章节。

URL 剖析

URL 剖析函数聚焦于将 URL 字符串分割成其组件，或将 URL 组件组合成 URL 字符串。

urllib.parse. urlparse ( urlstring , scheme='' , allow_fragments=True )

将 URL 剖析成 6 个组件，返回 6 项 命名元组 。这相当于一般 URL 结构： scheme://netloc/path;parameters?query#fragment . Each tuple item is a string, possibly empty. The components are not broken up in smaller parts (for example, the network location is a single string), and % escapes are not expanded. The delimiters as shown above are not part of the result, except for a leading slash in the path component, which is retained if present. For example: 

>>> from urllib.parse import urlparse
>>> o = urlparse('http://www.cwi.nl:80/%7Eguido/Python.html')
>>> o
ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
            params='', query='', fragment='')
>>> o.scheme
'http'
>>> o.port
80
>>> o.geturl()
'http://www.cwi.nl:80/%7Eguido/Python.html'

遵循的句法规范在 RFC 1808 , urlparse recognizes a netloc only if it is properly introduced by ‘//’. Otherwise the input is presumed to be a relative URL and thus to start with a path component. 

>>> from urllib.parse import urlparse
>>> urlparse('//www.cwi.nl:80/%7Eguido/Python.html')
ParseResult(scheme='', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
            params='', query='', fragment='')
>>> urlparse('www.cwi.nl/%7Eguido/Python.html')
ParseResult(scheme='', netloc='', path='www.cwi.nl/%7Eguido/Python.html',
            params='', query='', fragment='')
>>> urlparse('help/Python.html')
ParseResult(scheme='', netloc='', path='help/Python.html', params='',
            query='', fragment='')

The scheme argument gives the default addressing scheme, to be used only if the URL does not specify one. It should be the same type (text or bytes) as urlstring , except that the default value '' is always allowed, and is automatically converted to b'' 若合适。

若 allow_fragments argument is false, fragment identifiers are not recognized. Instead, they are parsed as part of the path, parameters or query component, and fragment is set to the empty string in the return value.

返回值为 命名元组 , which means that its items can be accessed by index or as named attributes, which are:

属性 索引 值 值若不存在
scheme 0 URL 方案说明符 scheme 参数
netloc 1 网络位置部分 空字符串
path 2 分层路径 空字符串
params 3 用于最后路径元素的参数 空字符串
query 4 查询组件 空字符串
fragment 5 片段标识符 空字符串
username 用户名 None
password 口令 None
hostname 主机名 (小写) None
port 整数形式的端口号 (若存在) None

读取 port 属性将引发 ValueError if an invalid port is specified in the URL. See section 结构化剖析结果 for more information on the result object.

不匹配的方括号内 netloc 属性将引发 ValueError .

字符在 netloc attribute that decompose under NFKC normalization (as used by the IDNA encoding) into any of / , ? , # , @ ，或 : 将引发 ValueError . If the URL is decomposed before parsing, no error will be raised.

As is the case with all named tuples, the subclass has a few additional methods and attributes that are particularly useful. One such method is _replace() 。 _replace() method will return a new ParseResult object replacing specified fields with new values. 

>>> from urllib.parse import urlparse
>>> u = urlparse('//www.cwi.nl:80/%7Eguido/Python.html')
>>> u
ParseResult(scheme='', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
            params='', query='', fragment='')
>>> u._replace(scheme='http')
ParseResult(scheme='http', netloc='www.cwi.nl:80', path='/%7Eguido/Python.html',
            params='', query='', fragment='')

3.2 版改变： 添加 IPv6 URL 剖析能力。

3.3 版改变： The fragment is now parsed for all URL schemes (unless allow_fragment is false), in accordance with RFC 3986 . Previously, a whitelist of schemes that support fragments existed.

3.6 版改变： 超出范围的端口号现在引发 ValueError ，而不是返回 None .

3.8 版改变： Characters that affect netloc parsing under NFKC normalization will now raise ValueError .

urllib.parse. parse_qs ( qs , keep_blank_values=False , strict_parsing=False , encoding='utf-8' , errors='replace' , max_num_fields=None , separator='&' )

Parse a query string given as a string argument (data of type application/x-www-form-urlencoded ). Data are returned as a dictionary. The dictionary keys are the unique query variable names and the values are lists of values for each name.

可选自变量 keep_blank_values is a flag indicating whether blank values in percent-encoded queries should be treated as blank strings. A true value indicates that blanks should be retained as blank strings. The default false value indicates that blank values are to be ignored and treated as if they were not included.

可选自变量 strict_parsing is a flag indicating what to do with parsing errors. If false (the default), errors are silently ignored. If true, errors raise a ValueError 异常。

可选 encoding and errors 参数指定如何将百分比编码序列解码成 Unicode 字符，被接受通过 bytes.decode() 方法。

可选自变量 max_num_fields is the maximum number of fields to read. If set, then throws a ValueError if there are more than max_num_fields fields read.

可选自变量 separator is the symbol to use for separating the query arguments. It defaults to & .

使用 urllib.parse.urlencode() function (with the doseq parameter set to True ) to convert such dictionaries into query strings.

3.2 版改变： 添加 encoding and errors 参数。

3.8 版改变： 添加 max_num_fields 参数。

Changed in version 3.8.8: 添加 separator parameter with the default value of & . Python versions earlier than Python 3.8.8 allowed using both ; and & as query parameter separator. This has been changed to allow only a single separator key, with & as the default separator.

urllib.parse. parse_qsl ( qs , keep_blank_values=False , strict_parsing=False , encoding='utf-8' , errors='replace' , max_num_fields=None , separator='&' )

Parse a query string given as a string argument (data of type application/x-www-form-urlencoded ). Data are returned as a list of name, value pairs.

可选自变量 keep_blank_values is a flag indicating whether blank values in percent-encoded queries should be treated as blank strings. A true value indicates that blanks should be retained as blank strings. The default false value indicates that blank values are to be ignored and treated as if they were not included.

可选自变量 strict_parsing is a flag indicating what to do with parsing errors. If false (the default), errors are silently ignored. If true, errors raise a ValueError 异常。

可选 encoding and errors 参数指定如何将百分比编码序列解码成 Unicode 字符，被接受通过 bytes.decode() 方法。

可选自变量 max_num_fields is the maximum number of fields to read. If set, then throws a ValueError if there are more than max_num_fields fields read.

可选自变量 separator is the symbol to use for separating the query arguments. It defaults to & .

使用 urllib.parse.urlencode() function to convert such lists of pairs into query strings.

3.2 版改变： 添加 encoding and errors 参数。

3.8 版改变： 添加 max_num_fields 参数。

Changed in version 3.8.8: 添加 separator parameter with the default value of & . Python versions earlier than Python 3.8.8 allowed using both ; and & as query parameter separator. This has been changed to allow only a single separator key, with & as the default separator.

urllib.parse. urlunparse ( parts )

Construct a URL from a tuple as returned by urlparse() 。 parts argument can be any six-item iterable. This may result in a slightly different, but equivalent URL, if the URL that was parsed originally had unnecessary delimiters (for example, a ? with an empty query; the RFC states that these are equivalent).

urllib.parse. urlsplit ( urlstring , scheme='' , allow_fragments=True )

这类似于 urlparse() , but does not split the params from the URL. This should generally be used instead of urlparse() if the more recent URL syntax allowing parameters to be applied to each segment of the path portion of the URL (see RFC 2396 ) is wanted. A separate function is needed to separate the path segments and parameters. This function returns a 5-item 命名元组 : 

(addressing scheme, network location, path, query, fragment identifier).

返回值为 命名元组 , its items can be accessed by index or as named attributes:

属性 索引 值 值若不存在
scheme 0 URL 方案说明符 scheme 参数
netloc 1 网络位置部分 空字符串
path 2 分层路径 空字符串
query 3 查询组件 空字符串
fragment 4 片段标识符 空字符串
username 用户名 None
password 口令 None
hostname 主机名 (小写) None
port 整数形式的端口号 (若存在) None

读取 port 属性将引发 ValueError if an invalid port is specified in the URL. See section 结构化剖析结果 for more information on the result object.

不匹配的方括号内 netloc 属性将引发 ValueError .

字符在 netloc attribute that decompose under NFKC normalization (as used by the IDNA encoding) into any of / , ? , # , @ ，或 : 将引发 ValueError . If the URL is decomposed before parsing, no error will be raised.

3.6 版改变： 超出范围的端口号现在引发 ValueError ，而不是返回 None .

3.8 版改变： Characters that affect netloc parsing under NFKC normalization will now raise ValueError .

urllib.parse. urlunsplit ( parts )

Combine the elements of a tuple as returned by urlsplit() into a complete URL as a string. The parts argument can be any five-item iterable. This may result in a slightly different, but equivalent URL, if the URL that was parsed originally had unnecessary delimiters (for example, a ? with an empty query; the RFC states that these are equivalent).

urllib.parse. urljoin ( base , url , allow_fragments=True )

Construct a full (“absolute”) URL by combining a “base URL” ( base ) with another URL ( url ). Informally, this uses components of the base URL, in particular the addressing scheme, the network location and (part of) the path, to provide missing components in the relative URL. For example: 

>>> from urllib.parse import urljoin
>>> urljoin('http://www.cwi.nl/%7Eguido/Python.html', 'FAQ.html')
'http://www.cwi.nl/%7Eguido/FAQ.html'

The allow_fragments argument has the same meaning and default as for urlparse() .

注意

若 url is an absolute URL (that is, starting with // or scheme:// )， url ’s host name and/or scheme will be present in the result. For example: 

>>> urljoin('http://www.cwi.nl/%7Eguido/Python.html',
...         '//www.python.org/%7Eguido')
'http://www.python.org/%7Eguido'

If you do not want that behavior, preprocess the url with urlsplit() and urlunsplit() , removing possible scheme and netloc parts.

3.5 版改变： Behaviour updated to match the semantics defined in RFC 3986 .

urllib.parse. urldefrag ( url )

若 url contains a fragment identifier, return a modified version of url with no fragment identifier, and the fragment identifier as a separate string. If there is no fragment identifier in url ，返回 url unmodified and an empty string.

返回值为 命名元组 , its items can be accessed by index or as named attributes:

属性 索引 值 值若不存在
url 0 URL with no fragment 空字符串
fragment 1 片段标识符 空字符串

见章节 结构化剖析结果 for more information on the result object.

3.2 版改变： Result is a structured object rather than a simple 2-tuple.

urllib.parse. unwrap ( url )

Extract the url from a wrapped URL (that is, a string formatted as <URL:scheme://host/path> , <scheme://host/path> , URL:scheme://host/path or scheme://host/path )。若 url is not a wrapped URL, it is returned without changes.

剖析 ASCII 编码字节

The URL parsing functions were originally designed to operate on character strings only. In practice, it is useful to be able to manipulate properly quoted and encoded URLs as sequences of ASCII bytes. Accordingly, the URL parsing functions in this module all operate on bytes and bytearray objects in addition to str 对象。

若 str data is passed in, the result will also contain only str data. If bytes or bytearray data is passed in, the result will contain only bytes 数据。

试图混合 str 数据采用 bytes or bytearray in a single function call will result in a TypeError being raised, while attempting to pass in non-ASCII byte values will trigger UnicodeDecodeError .

To support easier conversion of result objects between str and bytes , all return values from URL parsing functions provide either an encode() method (when the result contains str data) or a decode() method (when the result contains bytes data). The signatures of these methods match those of the corresponding str and bytes methods (except that the default encoding is 'ascii' 而不是 'utf-8' ). Each produces a value of a corresponding type that contains either bytes data (for encode() 方法) 或 str data (for decode() 方法)。

Applications that need to operate on potentially improperly quoted URLs that may contain non-ASCII data will need to do their own decoding from bytes to characters before invoking the URL parsing methods.

The behaviour described in this section applies only to the URL parsing functions. The URL quoting functions use their own rules when producing or consuming byte sequences as detailed in the documentation of the individual URL quoting functions.

3.2 版改变： URL 剖析函数现在接受 ASCII 编码的字节序列

结构化剖析结果

结果对象来自 urlparse() , urlsplit() and urldefrag() 函数是子类化的 tuple type. These subclasses add the attributes listed in the documentation for those functions, the encoding and decoding support described in the previous section, as well as an additional method:

urllib.parse.SplitResult. geturl ( )

Return the re-combined version of the original URL as a string. This may differ from the original URL in that the scheme may be normalized to lower case and empty components may be dropped. Specifically, empty parameters, queries, and fragment identifiers will be removed.

For urldefrag() results, only empty fragment identifiers will be removed. For urlsplit() and urlparse() results, all noted changes will be made to the URL returned by this method.

The result of this method remains unchanged if passed back through the original parsing function: 

>>> from urllib.parse import urlsplit
>>> url = 'HTTP://www.Python.org/doc/#'
>>> r1 = urlsplit(url)
>>> r1.geturl()
'http://www.Python.org/doc/'
>>> r2 = urlsplit(r1.geturl())
>>> r2.geturl()
'http://www.Python.org/doc/'

下列类提供结构化剖析结果的实现，当操作 str 对象：

class urllib.parse. DefragResult ( url , fragment )

具体类为 urldefrag() 结果包含 str 数据。 encode() 方法返回 DefragResultBytes 实例。

3.2 版新增。

class urllib.parse. ParseResult ( scheme , netloc , path , params , query , fragment )

具体类为 urlparse() 结果包含 str 数据。 encode() 方法返回 ParseResultBytes 实例。

class urllib.parse. SplitResult ( scheme , netloc , path , query , fragment )

具体类为 urlsplit() 结果包含 str 数据。 encode() 方法返回 SplitResultBytes 实例。

下列类提供剖析结果的实现，当操作 bytes or bytearray 对象：

class urllib.parse. DefragResultBytes ( url , fragment )

具体类为 urldefrag() 结果包含 bytes 数据。 decode() 方法返回 DefragResult 实例。

3.2 版新增。

class urllib.parse. ParseResultBytes ( scheme , netloc , path , params , query , fragment )

具体类为 urlparse() 结果包含 bytes 数据。 decode() 方法返回 ParseResult 实例。

3.2 版新增。

class urllib.parse. SplitResultBytes ( scheme , netloc , path , query , fragment )

具体类为 urlsplit() 结果包含 bytes 数据。 decode() 方法返回 SplitResult 实例。

3.2 版新增。

URL 引用

URL 引用函数聚焦于获取程序数据并通过引用特殊字符和非 ASCII 适当编码文本，使其安全用作 URL 组件。它们还支持从 URL 组件内容重新创建原始数据的这些的反转操作，若上文 URL 剖析函数尚未涵盖任务。

urllib.parse. quote ( string , safe='/' , encoding=None , errors=None )

替换特殊字符在 string 使用 %xx 转义。字母、数字及字符 '_.-~' are never quoted. By default, this function is intended for quoting the path section of URL. The optional safe 参数指定不应该被引用的额外 ASCII 字符 — 其默认值为 '/' .

string 可以是 str 或 bytes .

3.7 版改变： 移动从 RFC 2396 to RFC 3986 用于引用 URL 字符串。~ 现在包括在未预留字符集中。

可选 encoding and errors 参数指定如何处理非 ASCII 字符，如接受通过 str.encode() 方法。 encoding 默认为 'utf-8' . errors 默认为 'strict' ，意味着不被支持的字符会引发 UnicodeEncodeError . encoding and errors 不必提供若 string 是 bytes ，或 TypeError 被引发。

注意， quote(string, safe, encoding, errors) 相当于 quote_from_bytes(string.encode(encoding, errors), safe) .

范例： quote('/El Niño/') 产生 '/El%20Ni%C3%B1o/' .

urllib.parse. quote_plus ( string , safe='' , encoding=None , errors=None )

像 quote() , but also replace spaces by plus signs, as required for quoting HTML form values when building up a query string to go into a URL. Plus signs in the original string are escaped unless they are included in safe 。它也没有 safe 默认为 '/' .

范例： quote_plus('/El Niño/') 产生 '%2FEl+Ni%C3%B1o%2F' .

urllib.parse. quote_from_bytes ( bytes , safe='/' )

像 quote() ，但接受 bytes 对象而不是 str ，且不履行字符串到字节的编码。

范例： quote_from_bytes(b'a&\xef') 产生 'a%26%EF' .

urllib.parse. unquote ( string , encoding='utf-8' , errors='replace' )

替换 %xx escapes by their single-character equivalent. The optional encoding and errors 参数指定如何将百分比编码序列解码成 Unicode 字符，被接受通过 bytes.decode() 方法。

string 必须为 str .

encoding 默认为 'utf-8' . errors 默认为 'replace' ，意味着无效序列会被占位字符所替换。

范例： unquote('/El%20Ni%C3%B1o/') 产生 '/El Niño/' .

urllib.parse. unquote_plus ( string , encoding='utf-8' , errors='replace' )

像 unquote() , but also replace plus signs by spaces, as required for unquoting HTML form values.

string 必须为 str .

范例： unquote_plus('/El+Ni%C3%B1o/') 产生 '/El Niño/' .

urllib.parse. unquote_to_bytes ( string )

替换 %xx escapes by their single-octet equivalent, and return a bytes 对象。

string 可以是 str 或 bytes .

若它是 str ，未转义的非 ASCII 字符在 string 被编码成 UTF-8 字节。

范例： unquote_to_bytes('a%26%EF') 产生 b'a&\xef' .

urllib.parse. urlencode ( query , doseq=False , safe='' , encoding=None , errors=None , quote_via=quote_plus )

转换映射对象或 2 元素元组序列，其中可能包含 str or bytes objects, to a percent-encoded ASCII text string. If the resultant string is to be used as a data for POST operation with the urlopen() function, then it should be encoded to bytes, otherwise it would result in a TypeError .

The resulting string is a series of key=value pairs separated by '&' characters, where both key and value are quoted using the quote_via function. By default, quote_plus() is used to quote the values, which means spaces are quoted as a '+' character and ‘/’ characters are encoded as %2F , which follows the standard for GET requests ( application/x-www-form-urlencoded ). An alternate function that can be passed as quote_via is quote() , which will encode spaces as %20 and not encode ‘/’ characters. For maximum control of what is quoted, use quote and specify a value for safe .

When a sequence of two-element tuples is used as the query argument, the first element of each tuple is a key and the second is a value. The value element in itself can be a sequence and in that case, if the optional parameter doseq is evaluates to True , individual key=value pairs separated by '&' are generated for each element of the value sequence for the key. The order of parameters in the encoded string will match the order of parameter tuples in the sequence.

The safe , encoding ，和 errors parameters are passed down to quote_via ( encoding and errors parameters are only passed when a query element is a str ).

To reverse this encoding process, parse_qs() and parse_qsl() are provided in this module to parse query strings into Python data structures.

参考 urllib 范例 to find out how urlencode method can be used for generating query string for a URL or data for POST.

3.2 版改变： query 参数支持 bytes 和字符串对象。

3.5 版新增： quote_via 参数。

另请参阅

RFC 3986 - 统一资源标识符

This is the current standard (STD66). Any changes to urllib.parse module should conform to this. Certain deviations could be observed, which are mostly for backward compatibility purposes and for certain de-facto parsing requirements as commonly observed in major browsers.

RFC 2732 - Format for Literal IPv6 Addresses in URL’s.

This specifies the parsing requirements of IPv6 URLs.

RFC 2396 - Uniform Resource Identifiers (URI): Generic Syntax

Document describing the generic syntactic requirements for both Uniform Resource Names (URNs) and Uniform Resource Locators (URLs).

RFC 2368 - The mailto URL scheme.

Parsing requirements for mailto URL schemes.

RFC 1808 - Relative Uniform Resource Locators

This Request For Comments includes the rules for joining an absolute and a relative URL, including a fair number of “Abnormal Examples” which govern the treatment of border cases.

RFC 1738 - Uniform Resource Locators (URL)

This specifies the formal syntax and semantics of absolute URLs.

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