Validator

public abstract class Validator extends Object

A processor that checks an XML document against Schema.

A validator is a thread-unsafe and non-reentrant object. In other words, it is the application's responsibility to make sure that one Validator object is not used from more than one thread at any given time, and while the validate method is invoked, applications may not recursively call the validate method.

Note that while the validate(javax.xml.transform.Source) and validate(javax.xml.transform.Source, javax.xml.transform.Result) methods take a Source instance, the Source instance must be a SAXSource, DOMSource, StAXSource or StreamSource.

Protected Constructor Summary

Validator()
Constructor for derived classes.

Public Method Summary

abstract ErrorHandler
getErrorHandler()
Gets the current ErrorHandler set to this Validator.
boolean
getFeature(String name)
Look up the value of a feature flag.
Object
getProperty(String name)
Look up the value of a property.
abstract LSResourceResolver
getResourceResolver()
Gets the current LSResourceResolver set to this Validator.
abstract void
reset()

Reset this Validator to its original configuration.

abstract void
setErrorHandler(ErrorHandler errorHandler)
Sets the ErrorHandler to receive errors encountered during the validate method invocation.
void
setFeature(String name, boolean value)
Set the value of a feature flag.
void
setProperty(String name, Object object)
Set the value of a property.
abstract void
setResourceResolver(LSResourceResolver resourceResolver)
Sets the LSResourceResolver to customize resource resolution while in a validation episode.
void
validate(Source source)
Validates the specified input.
abstract void
validate(Source source, Result result)
Validates the specified input and send the augmented validation result to the specified output.

Inherited Method Summary

Protected Constructors

protected Validator ()

Constructor for derived classes.

The constructor does nothing.

Derived classes must create Validator objects that have null ErrorHandler and null LSResourceResolver.

Public Methods

public abstract ErrorHandler getErrorHandler ()

Gets the current ErrorHandler set to this Validator.

Returns

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 Validator 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 Validator recognizes the feature name but cannot determine its value at this time.
NullPointerException When the name parameter is null.

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 Validator 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.

Validators 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.

public abstract LSResourceResolver getResourceResolver ()

Gets the current LSResourceResolver set to this Validator.

Returns

public abstract void reset ()

Reset this Validator to its original configuration.

Validator is reset to the same state as when it was created with Schema.newValidator(). reset() is designed to allow the reuse of existing Validators thus saving resources associated with the creation of new Validators.

The reset Validator is not guaranteed to have the same LSResourceResolver or ErrorHandler Objects, e.g. Object.equals(Object). It is guaranteed to have a functionally equal LSResourceResolver and ErrorHandler.

public abstract void setErrorHandler (ErrorHandler errorHandler)

Sets the ErrorHandler to receive errors encountered during the validate method invocation.

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 caller of the validate method will be thrown the same Throwable object.

Validator 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 implements ErrorHandler {
     public void fatalError( SAXParseException e ) throws SAXException {
         throw e;
     }
     public void error( SAXParseException e ) throws SAXException {
         throw e;
     }
     public void warning( SAXParseException e ) throws SAXException {
         // noop
     }
 }
 

When a new Validator 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 Validator parses schemas, although Validators are not required to recognize any specific property names.

The feature name is any fully-qualified URI. It is possible for a Validator 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 Validator recognizes the feature name but cannot set the requested value.
NullPointerException When the name parameter is null.

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 Validator 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.

Validators 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 Validator 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.

Validator 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 Validator will abort the parsing and the caller of the validate method will receive the same RuntimeException.

When a new Validator object is created, initially this field is set to null.

Parameters
resourceResolver A new resource resolver to be set. This parameter can be null.

public void validate (Source source)

Validates the specified input.

This is just a convenience method of:

 validate(source,null);
 

Parameters
source

public abstract void validate (Source source, Result result)

Validates the specified input and send the augmented validation result to the specified output.

This method places the following restrictions on the types of the Source/Result accepted.

Source/Result accepted:

SAXSource DOMSource StreamSource
null OK OK OK OK
SAXResult OK Err Err Err
DOMResult Err OK Err Err
StreamResult Err Err Err OK

To validate one Source into another kind of Result, use the identity transformer (see TransformerFactory.newTransformer()).

Errors found during the validation is sent to the specified ErrorHandler.

If a document is valid, or if a document contains some errors but none of them were fatal and the ErrorHandler didn't throw any exception, then the method returns normally.

Parameters
source XML to be validated. Must not be null.
result The Result object that receives (possibly augmented) XML. This parameter can be null if the caller is not interested in it. Note that when a DOMResult is used, a validator might just pass the same DOM node from DOMSource to DOMResult (in which case source.getNode()==result.getNode()), it might copy the entire DOM tree, or it might alter the node given by the source.
Throws
IllegalArgumentException If the Result type doesn't match the Source type, or if the specified source is not a SAXSource, DOMSource or StreamSource.
SAXException If the ErrorHandler throws a SAXException or if a fatal error is found and the ErrorHandler returns normally.
IOException If the validator is processing a SAXSource and the underlying XMLReader throws an IOException.
NullPointerException If the source parameter is null.
See Also