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.