gnu.xml.pipeline
Class DomConsumer
java.lang.Object
|
+--gnu.xml.pipeline.DomConsumer
All Implemented Interfaces:
EventConsumerKnown Direct Subclasses:
Consumer
public class
DomConsumerextends java.lang.Object
implements
EventConsumer This consumer builds a DOM Document from its input, acting either as a
pipeline terminus or as an intermediate buffer. When a document's worth
of events has been delivered to this consumer, that document is read with
a
DomParser and sent to the next consumer. It is also available
as a read-once property.
The DOM tree is constructed as faithfully as possible. There are some
complications since a DOM should expose behaviors that can't be implemented
without API backdoors into that DOM, and because some SAX parsers don't
report all the information that DOM permits to be exposed. The general
problem areas involve information from the Document Type Declaration (DTD).
DOM only represents a limited subset, but has some behaviors that depend
on much deeper knowledge of a document's DTD. You shouldn't have much to
worry about unless you change handling of "noise" nodes from its default
setting (which ignores them all); note if you use JAXP to populate your
DOM trees, it wants to save "noise" nodes by default. (Such nodes include
ignorable whitespace, comments, entity references and CDATA boundaries.)
Otherwise, your
main worry will be if you use a SAX parser that doesn't flag ignorable
whitespace unless it's validating (few don't).
The SAX2 events used as input must contain XML Names for elements
and attributes, with original prefixes. In SAX2,
this is optional unless the "namespace-prefixes" parser feature is set.
Moreover, many application components won't provide completely correct
structures anyway.
Before you convert a DOM to an output document,
you should plan to postprocess it to create or repair such namespace
information. The
NSFilter pipeline stage does such work.
Note: changes late in DOM L2 process made it impractical to
attempt to create the DocumentType node in any implementation-neutral way,
much less to populate it (L1 didn't support even creating such nodes).
To create and populate such a node, subclass the inner
DomConsumer.Handler class and teach it about the backdoors into
whatever DOM implementation you want. It's possible that some revised
DOM API (L3?) will make this problem solvable again.
- David Brownell
DomParser
DomConsumer
public DomConsumer(java.lang.Class impl, EventConsumer n)
Configures this consumer as a buffer/filter, using the specified
DOM implementation when constructing its result value.
This event consumer acts as a buffer and filter, in that it
builds a DOM tree and then writes it out when
endDocument
is invoked. Because of the limitations of DOM, much information
will as a rule not be seen in that replay. To get a full fidelity
copy of the input event stream, use a
TeeConsumer.
- impl - class implementing org.w3c.dom.Document Document
which publicly exposes a default constructor
- n - receives a "replayed" sequence of parse events when
the endDocument method is invoked.
SAXException
- when there is a problem creating an
empty DOM document using the specified DOM implementation
DomConsumer
public DomConsumer(java.lang.Class impl)
Configures this pipeline terminus to use the specified implementation
of DOM when constructing its result value.
- impl - class implementing org.w3c.dom.Document Document
which publicly exposes a default constructor
SAXException
- when there is a problem creating an
empty DOM document using the specified implementation
getContentHandler
public final ContentHandler getContentHandler()
Returns the document handler being used.
getDocument
public final Document getDocument()
Returns the document constructed from the preceding
sequence of events. This method should not be
used again until another sequence of events has been
given to this EventConsumer.
getDTDHandler
public final DTDHandler getDTDHandler()
Returns the DTD handler being used.
getProperty
public final Object getProperty(java.lang.String id)
Returns the lexical handler being used.
(DOM construction can't really use declaration handlers.)
- id
isHidingCDATA
public final boolean isHidingCDATA()
Returns true if the consumer is saving CDATA boundaries, or
false (the default) otherwise.
setHidingCDATA
isHidingComments
public final boolean isHidingComments()
Returns true if the consumer is hiding comments (the default),
and false if they should be placed into the output document.
setHidingComments
isHidingReferences
public final boolean isHidingReferences()
Returns true if the consumer is hiding entity references nodes
(the default), and false if EntityReference nodes should
instead be created. Such EntityReference nodes will normally be
empty, unless an implementation arranges to populate them and then
turn them back into readonly objects.
setHidingReferences
isHidingWhitespace
public final boolean isHidingWhitespace()
Returns true if the consumer is hiding ignorable whitespace
(the default), and false if such whitespace should be placed
into the output document as children of element nodes.
setHidingWhitespace
setErrorHandler
public void setErrorHandler(ErrorHandler handler)
- handler
setHandler
protected void setHandler(DomConsumer.Handler h)
This is the hook through which a subclass provides a handler
which knows how to access DOM extensions, specific to some
implementation, to record additional data in a DOM.
Treat this as part of construction; don't call it except
before (or between) parses.
- h
setHidingCDATA
public final void setHidingCDATA(boolean flag)
Controls whether the consumer will save CDATA boundaries.
- flag - True to treat CDATA text differently from other
text nodes
isHidingCDATA
setHidingComments
public final void setHidingComments(boolean flag)
Controls whether the consumer is hiding comments.
- flag
isHidingComments
setHidingReferences
public final void setHidingReferences(boolean flag)
Controls whether the consumer will hide entity expansions,
or will instead mark them with entity reference nodes.
- flag - False if entity reference nodes will appear
isHidingReferences
setHidingWhitespace
public final void setHidingWhitespace(boolean flag)
Controls whether the consumer hides ignorable whitespace
- flag
isHidingComments