Streaming validator that works on SAX stream.
A ValidatorHandler
object is not thread-safe and not reentrant.
In other words, it is the application's responsibility to make
sure that one ValidatorHandler
object is not used from
more than one thread at any given time.
ValidatorHandler
checks if the SAX events follow
the set of constraints described in the associated Schema
,
and additionally it may modify the SAX events (for example
by adding default values, etc.)
ValidatorHandler
extends from ContentHandler
,
but it refines the underlying ContentHandler
in
the following way:
- startElement/endElement events must receive non-null String
for
uri
, localName
, and qname
,
even though SAX allows some of them to be null.
Similarly, the user-specified ContentHandler
will receive non-null
Strings for all three parameters.
- Applications must ensure that
ValidatorHandler
's
ContentHandler.startPrefixMapping(String,String)
and
ContentHandler.endPrefixMapping(String)
are invoked
properly. Similarly, the user-specified ContentHandler
will receive startPrefixMapping/endPrefixMapping events.
If the ValidatorHandler
introduces additional namespace
bindings, the user-specified ContentHandler
will receive
additional startPrefixMapping/endPrefixMapping events.
Attributes
for the
ContentHandler.startElement(String,String,String,Attributes)
method
may or may not include xmlns* attributes.
A ValidatorHandler
is automatically reset every time
the startDocument method is invoked.
Recognized Properties and Features
This spec defines the following feature that must be recognized
by all ValidatorHandler
implementations.
http://xml.org/sax/features/namespace-prefixes
This feature controls how a ValidatorHandler
introduces
namespace bindings that were not present in the original SAX event
stream.
When this feature is set to true, it must make
sure that the user's ContentHandler
will see
the corresponding xmlns*
attribute in
the Attributes
object of the
ContentHandler.startElement(String,String,String,Attributes)
callback. Otherwise, xmlns*
attributes must not be
added to Attributes
that's passed to the
user-specified ContentHandler
.
(Note that regardless of this switch, namespace bindings are
always notified to applications through
ContentHandler.startPrefixMapping(String,String)
and
ContentHandler.endPrefixMapping(String)
methods of the
ContentHandler
specified by the user.)
Note that this feature does NOT affect the way
a ValidatorHandler
receives SAX events. It merely
changes the way it augments SAX events.
This feature is set to false
by default.