21.8. urllib.parse — 把 URL 剖析成组件 ¶

21.8.1. URL 剖析 ¶

The URL parsing functions focus on splitting a URL string into its components, or on combining URL components into a URL string.

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

Parse a URL into six components, returning a 6-tuple. This corresponds to the general structure of a URL: 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   # doctest: +NORMALIZE_WHITESPACE
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'
										

Following the syntax specifications in 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='')
										

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.

The return value is actually an instance of a subclass of tuple . This class has the following additional read-only convenience attributes:

属性	索引	Value	Value if not present
scheme	0	URL scheme specifier	scheme parameter
netloc	1	Network location part	空字符串
path	2	Hierarchical path	空字符串
params	3	Parameters for last path element	空字符串
query	4	Query component	空字符串
fragment	5	Fragment identifier	空字符串
username		User name	None
password		Password	None
hostname		Host name (lower case)	None
port		Port number as integer, if present	None

Reading the port attribute will raise a 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.

Unmatched square brackets in the netloc attribute will raise a ValueError .

3.2 版改变： Added IPv6 URL parsing capabilities.

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： Out-of-range port numbers now raise ValueError , instead of returning None .

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

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 parameters specify how to decode percent-encoded sequences into Unicode characters, as accepted by the 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.

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。

3.6.8 版改变： 添加 max_num_fields 参数。

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

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 parameters specify how to decode percent-encoded sequences into Unicode characters, as accepted by the 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.

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。

3.6.8 版改变： 添加 max_num_fields 参数。

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 ) ¶

This is similar to 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-tuple: (addressing scheme, network location, path, query, fragment identifier).

The return value is actually an instance of a subclass of tuple . This class has the following additional read-only convenience attributes:

属性	索引	Value	Value if not present
scheme	0	URL scheme specifier	scheme parameter
netloc	1	Network location part	空字符串
path	2	Hierarchical path	空字符串
query	3	Query component	空字符串
fragment	4	Fragment identifier	空字符串
username		User name	None
password		Password	None
hostname		Host name (lower case)	None
port		Port number as integer, if present	None

Reading the port attribute will raise a 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.

Unmatched square brackets in the netloc attribute will raise a ValueError .

3.6 版改变： Out-of-range port numbers now raise ValueError , instead of returning None .

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'
										

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:// ), the 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.

The return value is actually an instance of a subclass of tuple . This class has the following additional read-only convenience attributes:

属性	索引	Value	Value if not present
url	0	URL with no fragment	空字符串
fragment	1	Fragment identifier	空字符串

See section 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.

21.8.2. 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 data.

Attempting to mix str data with 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() methods) or str data (for decode() methods).

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.

21.8.3. 结构化剖析结果 ¶

The result objects from the urlparse() , urlsplit() and urldefrag() functions are subclasses of the 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/'
										

The following classes provide the implementations of the structured parse results when operating on str 对象：

class urllib.parse. DefragResult ( url , fragment ) ¶

Concrete class for urldefrag() results containing str data. The encode() method returns a DefragResultBytes 实例。

3.2 版新增。

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

Concrete class for urlparse() results containing str data. The encode() method returns a ParseResultBytes 实例。

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

Concrete class for urlsplit() results containing str data. The encode() method returns a SplitResultBytes 实例。

The following classes provide the implementations of the parse results when operating on bytes or bytearray 对象：

class urllib.parse. DefragResultBytes ( url , fragment ) ¶

Concrete class for urldefrag() results containing bytes data. The decode() method returns a DefragResult 实例。

3.2 版新增。

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

Concrete class for urlparse() results containing bytes data. The decode() method returns a ParseResult 实例。

3.2 版新增。

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

Concrete class for urlsplit() results containing bytes data. The decode() method returns a SplitResult 实例。

3.2 版新增。

21.8.4. URL Quoting ¶

The URL quoting functions focus on taking program data and making it safe for use as URL components by quoting special characters and appropriately encoding non-ASCII text. They also support reversing these operations to recreate the original data from the contents of a URL component if that task isn’t already covered by the URL parsing functions above.

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

Replace special characters in string 使用 %xx escape. Letters, digits, and the characters '_.-' are never quoted. By default, this function is intended for quoting the path section of URL. The optional safe parameter specifies additional ASCII characters that should not be quoted — its default value is '/' .

string may be either a str 或 bytes .

可选 encoding and errors parameters specify how to deal with non-ASCII characters, as accepted by the str.encode() 方法。 encoding 默认为 'utf-8' . errors 默认为 'strict' , meaning unsupported characters raise a UnicodeEncodeError . encoding and errors must not be supplied if 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/') yields '/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 . It also does not have safe default to '/' .

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

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

像 quote() , but accepts a bytes object rather than a str , and does not perform string-to-bytes encoding.

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

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

Replace %xx escapes by their single-character equivalent. The optional encoding and errors parameters specify how to decode percent-encoded sequences into Unicode characters, as accepted by the bytes.decode() 方法。

string 必须是 str .

encoding 默认为 'utf-8' . errors 默认为 'replace' , meaning invalid sequences are replaced by a placeholder character.

范例： unquote('/El%20Ni%C3%B1o/') yields '/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 必须是 str .

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

urllib.parse. unquote_to_bytes ( string ) ¶

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

string may be either a str 或 bytes .

若它是 str , unescaped non-ASCII characters in string are encoded into UTF-8 bytes.

范例： unquote_to_bytes('a%26%EF') yields 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.

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.

Refer to 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。