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
, andqname
, even though SAX allows some of them to be null. Similarly, the user-specifiedContentHandler
will receive non-null Strings for all three parameters. - Applications must ensure that
ValidatorHandler
'sContentHandler.startPrefixMapping(String, String)
andContentHandler.endPrefixMapping(String)
are invoked properly. Similarly, the user-specifiedContentHandler
will receive startPrefixMapping/endPrefixMapping events. If theValidatorHandler
introduces additional namespace bindings, the user-specifiedContentHandler
will receive additional startPrefixMapping/endPrefixMapping events. Attributes
for theContentHandler.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.
Protected Constructor Summary
ValidatorHandler()
Constructor for derived classes.
|
Public Method Summary
abstract ContentHandler |
getContentHandler()
Gets the
ContentHandler which receives the
augmented validation result. |
abstract ErrorHandler |
getErrorHandler()
Gets the current
ErrorHandler set to this ValidatorHandler . |
boolean | |
Object | |
abstract LSResourceResolver |
getResourceResolver()
Gets the current
LSResourceResolver set to this ValidatorHandler . |
abstract TypeInfoProvider |
getTypeInfoProvider()
Obtains the
TypeInfoProvider implementation of this
ValidatorHandler . |
abstract void |
setContentHandler(ContentHandler receiver)
Sets the
ContentHandler which receives
the augmented validation result. |
abstract void |
setErrorHandler(ErrorHandler errorHandler)
Sets the
ErrorHandler to receive errors encountered
during the validation. |
void | |
void | |
abstract void |
setResourceResolver(LSResourceResolver resourceResolver)
Sets the
LSResourceResolver to customize
resource resolution while in a validation episode. |
Inherited Method Summary
Protected Constructors
protected ValidatorHandler ()
Constructor for derived classes.
The constructor does nothing.
Derived classes must create ValidatorHandler
objects that have
null ErrorHandler
and
null LSResourceResolver
.
Public Methods
public abstract ContentHandler getContentHandler ()
Gets the ContentHandler
which receives the
augmented validation result.
Returns
- This method returns the object that was last set through
the
getContentHandler()
method, or null if that method has never been called since thisValidatorHandler
has created.
See Also
public abstract ErrorHandler getErrorHandler ()
Gets the current ErrorHandler
set to this ValidatorHandler
.
Returns
- This method returns the object that was last set through
the
setErrorHandler(ErrorHandler)
method, or null if that method has never been called since thisValidatorHandler
has created.
See Also
public boolean getFeature (String name)
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.
Parameters
name | The feature name, which is a non-null fully-qualified URI. |
---|
Returns
- The current value of the feature (true or false).
Throws
SAXNotRecognizedException | If the feature value can't be assigned or retrieved. |
---|---|
SAXNotSupportedException | When the
ValidatorHandler recognizes the feature name but
cannot determine its value at this time. |
NullPointerException | When the name parameter is null. |
See Also
public Object getProperty (String name)
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.
Parameters
name | The property name, which is a non-null fully-qualified URI. |
---|
Returns
- The current value of the property.
Throws
SAXNotRecognizedException | If the property value can't be assigned or retrieved. |
---|---|
SAXNotSupportedException | When the XMLReader recognizes the property name but cannot determine its value at this time. |
NullPointerException | When the name parameter is null. |
See Also
public abstract LSResourceResolver getResourceResolver ()
Gets the current LSResourceResolver
set to this ValidatorHandler
.
Returns
- This method returns the object that was last set through
the
setResourceResolver(LSResourceResolver)
method, or null if that method has never been called since thisValidatorHandler
has created.
See Also
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.
Returns
- null if the validator / schema language does not support
the notion of
TypeInfo
. Otherwise a non-null validTypeInfoProvider
.
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()
, orContentHandler.endDocument()
are invoked on aValidatorHandler
, the same method on the user-specifiedContentHandler
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.
Parameters
receiver | A ContentHandler or a null value.
|
---|
public abstract void setErrorHandler (ErrorHandler errorHandler)
Sets the ErrorHandler
to receive errors encountered
during the validation.
Error handler can be used to customize the error handling process
during a validation. When an ErrorHandler
is set,
errors found during the validation will be first sent
to the ErrorHandler
.
The error handler can abort further validation immediately
by throwing SAXException
from the handler. Or for example
it can print an error to the screen and try to continue the
validation by returning normally from the ErrorHandler
If any Throwable
is thrown from an ErrorHandler
,
the same Throwable
object will be thrown toward the
root of the call stack.
ValidatorHandler
is not allowed to
throw SAXException
without first reporting it to
ErrorHandler
.
When the ErrorHandler
is null, the implementation will
behave as if the following ErrorHandler
is set:
class DraconianErrorHandler implementsErrorHandler
{ public void fatalError(SAXParseException
e ) throwsSAXException
{ throw e; } public void error(SAXParseException
e ) throwsSAXException
{ throw e; } public void warning(SAXParseException
e ) throwsSAXException
{ // noop } }
When a new ValidatorHandler
object is created, initially
this field is set to null.
Parameters
errorHandler | A new error handler to be set. This parameter can be null. |
---|
public void setFeature (String name, boolean value)
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.
Parameters
name | The feature name, which is a non-null fully-qualified URI. |
---|---|
value | The requested value of the feature (true or false). |
Throws
SAXNotRecognizedException | If the feature value can't be assigned or retrieved. |
---|---|
SAXNotSupportedException | When the
ValidatorHandler recognizes the feature name but
cannot set the requested value. |
NullPointerException | When the name parameter is null. |
See Also
public void setProperty (String name, Object object)
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.
Parameters
name | The property name, which is a non-null fully-qualified URI. |
---|---|
object | The requested value for the property. |
Throws
SAXNotRecognizedException | If the property value can't be assigned or retrieved. |
---|---|
SAXNotSupportedException | When the
ValidatorHandler recognizes the property name but
cannot set the requested value. |
NullPointerException | When the name parameter is null. |
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 implementsLSResourceResolver
{ publicLSInput
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.
Parameters
resourceResolver | A new resource resolver to be set. This parameter can be null. |
---|