20.12. xml.sax.xmlreader
— 用于 XML 解析器的接口¶
SAX 解析器实现了 XMLReader
接口。 它们是在一个 Python 模块中实现的,该模块必须提供一个 create_parser()
函数。 该函数由 xml.sax.make_parser()
不带参数地发起调用来创建新的解析器对象。
-
class
xml.sax.xmlreader.
XMLReader
¶ 可由 SAX 解析器继承的基类。
-
class
xml.sax.xmlreader.
IncrementalParser
¶ 在某些情况下,最好不要一次性地解析输入源,而是在可用的时候分块送入。 请注意读取器通常不会读取整个文件,它同样也是分块读取的; 并且
parse()
在处理完整个文档之前不会返回。 所以如果不希望parse()
出现阻塞行为则应当使用这些接口。当解析器被实例化时它已准备好立即开始接受来自 feed 方法的数据。 在通过调用 close 方法结束解析时 reset 方法也必须被调用以使解析器准备好接受新的数据,无论它是来自于 feed 还是使用 parse 方法。
请注意这些方法 不可 在解析期间被调用,即在 parse 被调用之后及其返回之前。
默认情况下,该类还使用 IncrementalParser 接口的 feed, close 和 reset 方法来实现 XMLReader 接口的 parse 方法以方便 SAX 2.0 驱动的编写者。
-
class
xml.sax.xmlreader.
Locator
¶ 用于关联一个 SAX 事件与一个文档位置的接口。 定位器对象只有在调用 DocumentHandler 的方法期间才会返回有效的结果;在其他任何时候,结果都是不可预测的。 如果信息不可用,这些方法可能返回
None
。
-
class
xml.sax.xmlreader.
InputSource
(system_id=None)¶ XMLReader
读取实体所需信息的封装。这个类可能包括了关于公有标识符、系统标识符、字节流(可能带有字符编码格式信息)和/或一个实体的字符流的信息。
Applications will create objects of this class for use in the
XMLReader.parse()
method and for returning from EntityResolver.resolveEntity.An
InputSource
belongs to the application, theXMLReader
is not allowed to modifyInputSource
objects passed to it from the application, although it may make copies and modify those.
-
class
xml.sax.xmlreader.
AttributesImpl
(attrs)¶ This is an implementation of the
Attributes
interface (see section The Attributes Interface). This is a dictionary-like object which represents the element attributes in astartElement()
call. In addition to the most useful dictionary operations, it supports a number of other methods as described by the interface. Objects of this class should be instantiated by readers; attrs must be a dictionary-like object containing a mapping from attribute names to attribute values.
-
class
xml.sax.xmlreader.
AttributesNSImpl
(attrs, qnames)¶ Namespace-aware variant of
AttributesImpl
, which will be passed tostartElementNS()
. It is derived fromAttributesImpl
, but understands attribute names as two-tuples of namespaceURI and localname. In addition, it provides a number of methods expecting qualified names as they appear in the original document. This class implements theAttributesNS
interface (see section The AttributesNS Interface).
20.12.1. XMLReader 对象¶
The XMLReader
interface supports the following methods:
-
XMLReader.
parse
(source)¶ Process an input source, producing SAX events. The source object can be a system identifier (a string identifying the input source – typically a file name or a URL), a file-like object, or an
InputSource
object. Whenparse()
returns, the input is completely processed, and the parser object can be discarded or reset.在 3.5 版更改: Added support of character streams.
-
XMLReader.
getContentHandler
()¶ Return the current
ContentHandler
.
-
XMLReader.
setContentHandler
(handler)¶ Set the current
ContentHandler
. If noContentHandler
is set, content events will be discarded.
-
XMLReader.
getDTDHandler
()¶ Return the current
DTDHandler
.
-
XMLReader.
setDTDHandler
(handler)¶ Set the current
DTDHandler
. If noDTDHandler
is set, DTD events will be discarded.
-
XMLReader.
getEntityResolver
()¶ Return the current
EntityResolver
.
-
XMLReader.
setEntityResolver
(handler)¶ Set the current
EntityResolver
. If noEntityResolver
is set, attempts to resolve an external entity will result in opening the system identifier for the entity, and fail if it is not available.
-
XMLReader.
getErrorHandler
()¶ Return the current
ErrorHandler
.
-
XMLReader.
setErrorHandler
(handler)¶ Set the current error handler. If no
ErrorHandler
is set, errors will be raised as exceptions, and warnings will be printed.
-
XMLReader.
setLocale
(locale)¶ Allow an application to set the locale for errors and warnings.
SAX parsers are not required to provide localization for errors and warnings; if they cannot support the requested locale, however, they must raise a SAX exception. Applications may request a locale change in the middle of a parse.
-
XMLReader.
getFeature
(featurename)¶ Return the current setting for feature featurename. If the feature is not recognized,
SAXNotRecognizedException
is raised. The well-known featurenames are listed in the modulexml.sax.handler
.
-
XMLReader.
setFeature
(featurename, value)¶ Set the featurename to value. If the feature is not recognized,
SAXNotRecognizedException
is raised. If the feature or its setting is not supported by the parser, SAXNotSupportedException is raised.
-
XMLReader.
getProperty
(propertyname)¶ Return the current setting for property propertyname. If the property is not recognized, a
SAXNotRecognizedException
is raised. The well-known propertynames are listed in the modulexml.sax.handler
.
-
XMLReader.
setProperty
(propertyname, value)¶ Set the propertyname to value. If the property is not recognized,
SAXNotRecognizedException
is raised. If the property or its setting is not supported by the parser, SAXNotSupportedException is raised.
20.12.2. IncrementalParser 对象¶
Instances of IncrementalParser
offer the following additional methods:
-
IncrementalParser.
feed
(data)¶ Process a chunk of data.
-
IncrementalParser.
close
()¶ Assume the end of the document. That will check well-formedness conditions that can be checked only at the end, invoke handlers, and may clean up resources allocated during parsing.
-
IncrementalParser.
reset
()¶ This method is called after close has been called to reset the parser so that it is ready to parse new documents. The results of calling parse or feed after close without calling reset are undefined.
20.12.3. Locator 对象¶
Instances of Locator
provide these methods:
-
Locator.
getColumnNumber
()¶ Return the column number where the current event begins.
-
Locator.
getLineNumber
()¶ Return the line number where the current event begins.
-
Locator.
getPublicId
()¶ Return the public identifier for the current event.
-
Locator.
getSystemId
()¶ Return the system identifier for the current event.
20.12.4. InputSource 对象¶
-
InputSource.
setPublicId
(id)¶ Sets the public identifier of this
InputSource
.
-
InputSource.
getPublicId
()¶ Returns the public identifier of this
InputSource
.
-
InputSource.
setSystemId
(id)¶ Sets the system identifier of this
InputSource
.
-
InputSource.
getSystemId
()¶ Returns the system identifier of this
InputSource
.
-
InputSource.
setEncoding
(encoding)¶ Sets the character encoding of this
InputSource
.The encoding must be a string acceptable for an XML encoding declaration (see section 4.3.3 of the XML recommendation).
The encoding attribute of the
InputSource
is ignored if theInputSource
also contains a character stream.
-
InputSource.
getEncoding
()¶ Get the character encoding of this InputSource.
-
InputSource.
setByteStream
(bytefile)¶ Set the byte stream (a binary file) for this input source.
The SAX parser will ignore this if there is also a character stream specified, but it will use a byte stream in preference to opening a URI connection itself.
If the application knows the character encoding of the byte stream, it should set it with the setEncoding method.
-
InputSource.
getByteStream
()¶ Get the byte stream for this input source.
The getEncoding method will return the character encoding for this byte stream, or
None
if unknown.
-
InputSource.
setCharacterStream
(charfile)¶ Set the character stream (a text file) for this input source.
If there is a character stream specified, the SAX parser will ignore any byte stream and will not attempt to open a URI connection to the system identifier.
-
InputSource.
getCharacterStream
()¶ Get the character stream for this input source.
20.12.5. The Attributes
Interface¶
Attributes
objects implement a portion of the mapping protocol, including the methods copy()
,
get()
, __contains__()
,
items()
, keys()
,
and values()
. The following methods
are also provided:
-
Attributes.
getLength
()¶ Return the number of attributes.
-
Attributes.
getNames
()¶ Return the names of the attributes.
-
Attributes.
getType
(name)¶ Returns the type of the attribute name, which is normally
'CDATA'
.
-
Attributes.
getValue
(name)¶ Return the value of attribute name.
20.12.6. The AttributesNS
Interface¶
This interface is a subtype of the Attributes
interface (see section
The Attributes Interface). All methods supported by that interface are also
available on AttributesNS
objects.
The following methods are also available:
-
AttributesNS.
getValueByQName
(name)¶ Return the value for a qualified name.
-
AttributesNS.
getNameByQName
(name)¶ Return the
(namespace, localname)
pair for a qualified name.
-
AttributesNS.
getQNameByName
(name)¶ Return the qualified name for a
(namespace, localname)
pair.
-
AttributesNS.
getQNames
()¶ Return the qualified names of all attributes.