Streaming validator that works on SAX stream.
A
ValidatorHandler
object is a thread-unsafe, non-reentrant object.
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.
getErrorHandler
public abstract ErrorHandler getErrorHandler()
getFeature
public boolean getFeature(String name)
throws SAXNotRecognizedException,
SAXNotSupportedException
Look up the value of a feature flag.
The feature name is any fully-qualified URI. It is
possible for a
ValidatorHandler
to recognize a feature name but
temporarily be unable to return its value.
Some feature values may be available only in specific
contexts, such as before, during, or after a validation.
Implementors are free (and encouraged) to invent their own features,
using names built on their own URIs.
name
- The feature name, which is a non-null fully-qualified URI.
- The current value of the feature (true or false).
getProperty
public Object getProperty(String name)
throws SAXNotRecognizedException,
SAXNotSupportedException
Look up the value of a property.
The property name is any fully-qualified URI. It is
possible for a
ValidatorHandler
to recognize a property name but
temporarily be unable to return its value.
Some property values may be available only in specific
contexts, such as before, during, or after a validation.
ValidatorHandler
s are not required to recognize any specific
property names.
Implementors are free (and encouraged) to invent their own properties,
using names built on their own URIs.
name
- The property name, which is a non-null fully-qualified URI.
- The current value of the property.
getTypeInfoProvider
public abstract TypeInfoProvider getTypeInfoProvider()
Obtains the
TypeInfoProvider
implementation of this
ValidatorHandler
.
The obtained
TypeInfoProvider
can be queried during a parse
to access the type information determined by the validator.
Some schema languages do not define the notion of type,
for those languages, this method may not be supported.
However, to be compliant with this specification, implementations
for W3C XML Schema 1.0 must support this operation.
- null if the validator / schema language does not support
the notion of
TypeInfo
.
Otherwise a non-null valid TypeInfoProvider
.
setContentHandler
public abstract void setContentHandler(ContentHandler receiver)
Sets the
ContentHandler
which receives
the augmented validation result.
When a
ContentHandler
is specified, a
ValidatorHandler
will work as a filter
and basically copy the incoming events to the
specified
ContentHandler
.
In doing so, a
ValidatorHandler
may modify
the events, for example by adding defaulted attributes.
A
ValidatorHandler
may buffer events to certain
extent, but to allow
ValidatorHandler
to be used
by a parser, the following requirement has to be met.
- When
ContentHandler.startElement(String,String,String,Attributes)
,
ContentHandler.endElement(String,String,String)
,
ContentHandler.startDocument()
, or
ContentHandler.endDocument()
are invoked on a ValidatorHandler
,
the same method on the user-specified ContentHandler
must be invoked for the same event before the callback
returns.
ValidatorHandler
may not introduce new elements that
were not present in the input.
ValidatorHandler
may not remove attributes that were
present in the input.
When a callback method on the specified
ContentHandler
throws an exception, the same exception object must be thrown
from the
ValidatorHandler
. The
ErrorHandler
should not be notified of such an exception.
This method can be called even during a middle of a validation.
setErrorHandler
public abstract void setErrorHandler(ErrorHandler errorHandler)
errorHandler
- A new error handler to be set. This parameter can be null.
setFeature
public void setFeature(String name,
boolean value)
throws SAXNotRecognizedException,
SAXNotSupportedException
Set the value of a feature flag.
Feature can be used to control the way a
ValidatorHandler
parses schemas, although
ValidatorHandler
s are not required
to recognize any specific property names.
The feature name is any fully-qualified URI. It is
possible for a
ValidatorHandler
to expose a feature value but
to be unable to change the current value.
Some feature values may be immutable or mutable only
in specific contexts, such as before, during, or after
a validation.
name
- The feature name, which is a non-null fully-qualified URI.value
- The requested value of the feature (true or false).
setProperty
public void setProperty(String name,
Object object)
throws SAXNotRecognizedException,
SAXNotSupportedException
Set the value of a property.
The property name is any fully-qualified URI. It is
possible for a
ValidatorHandler
to recognize a property name but
to be unable to change the current value.
Some property values may be immutable or mutable only
in specific contexts, such as before, during, or after
a validation.
ValidatorHandler
s are not required to recognize setting
any specific property names.
name
- The property name, which is a non-null fully-qualified URI.object
- The requested value for the property.
setResourceResolver
public abstract void setResourceResolver(LSResourceResolver resourceResolver)
Sets the
LSResourceResolver
to customize
resource resolution while in a validation episode.
ValidatorHandler
uses a
LSResourceResolver
when it needs to locate external resources while a validation,
although exactly what constitutes "locating external resources" is
up to each schema language.
When the
LSResourceResolver
is null, the implementation will
behave as if the following
LSResourceResolver
is set:
class DumbLSResourceResolver implements LSResourceResolver
{
public LSInput
resolveResource(
String publicId, String systemId, String baseURI) {
return null; // always return null
}
}
If a
LSResourceResolver
throws a
RuntimeException
(or instances of its derived classes),
then the
ValidatorHandler
will abort the parsing and
the caller of the
validate
method will receive
the same
RuntimeException
.
When a new
ValidatorHandler
object is created, initially
this field is set to null.
resourceResolver
- A new resource resolver to be set. This parameter can be null.