/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// $Id: ValidatorHandler.java 446598 2006-09-15 12:55:40Z jeremias $
package javax.xml.validation;
import org.w3c.dom.ls.LSResourceResolver;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.SAXNotRecognizedException;
import org.xml.sax.SAXNotSupportedException;
/**
* Streaming validator that works on SAX stream.
*
* <p>
* A {@link ValidatorHandler} object is a thread-unsafe, non-reentrant object.
* In other words, it is the application's responsibility to make
* sure that one {@link ValidatorHandler} object is not used from
* more than one thread at any given time.
*
* <p>
* {@link ValidatorHandler} checks if the SAX events follow
* the set of constraints described in the associated {@link Schema},
* and additionally it may modify the SAX events (for example
* by adding default values, etc.)
*
* <p>
* {@link ValidatorHandler} extends from {@link ContentHandler},
* but it refines the underlying {@link ContentHandler} in
* the following way:
* <ol>
* <li>startElement/endElement events must receive non-null String
* for <code>uri</code>, <code>localName</code>, and <code>qname</code>,
* even though SAX allows some of them to be null.
* Similarly, the user-specified {@link ContentHandler} will receive non-null
* Strings for all three parameters.
*
* <li>Applications must ensure that {@link ValidatorHandler}'s
* {@link ContentHandler#startPrefixMapping(String,String)} and
* {@link ContentHandler#endPrefixMapping(String)} are invoked
* properly. Similarly, the user-specified {@link ContentHandler}
* will receive startPrefixMapping/endPrefixMapping events.
* If the {@link ValidatorHandler} introduces additional namespace
* bindings, the user-specified {@link ContentHandler} will receive
* additional startPrefixMapping/endPrefixMapping events.
*
* <li>{@link org.xml.sax.Attributes} for the
* {@link ContentHandler#startElement(String,String,String,Attributes)} method
* may or may not include xmlns* attributes.
* </ol>
*
* <p>
* A {@link ValidatorHandler} is automatically reset every time
* the startDocument method is invoked.
*
* <h2>Recognized Properties and Features</h2>
* <p>
* This spec defines the following feature that must be recognized
* by all {@link ValidatorHandler} implementations.
*
* <h3><code>http://xml.org/sax/features/namespace-prefixes</code></h3>
* <p>
* This feature controls how a {@link 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 {@link ContentHandler} will see
* the corresponding <code>xmlns*</code> attribute in
* the {@link org.xml.sax.Attributes} object of the
* {@link ContentHandler#startElement(String,String,String,Attributes)}
* callback. Otherwise, <code>xmlns*</code> attributes must not be
* added to {@link org.xml.sax.Attributes} that's passed to the
* user-specified {@link ContentHandler}.
* <p>
* (Note that regardless of this switch, namespace bindings are
* always notified to applications through
* {@link ContentHandler#startPrefixMapping(String,String)} and
* {@link ContentHandler#endPrefixMapping(String)} methods of the
* {@link ContentHandler} specified by the user.)
*
* <p>
* Note that this feature does <em>NOT</em> affect the way
* a {@link ValidatorHandler} receives SAX events. It merely
* changes the way it augments SAX events.
*
* <p>This feature is set to <code>false</code> by default.</p>
*
* @author <a href="mailto:Kohsuke.Kawaguchi@Sun.com">Kohsuke Kawaguchi</a>
* @version $Revision: 446598 $, $Date: 2006-09-15 05:55:40 -0700 (Fri, 15 Sep 2006) $
* @since 1.5
*/
public abstract class ValidatorHandler implements ContentHandler {
/**
* Constructor for derived classes.
*
* <p>
* The constructor does nothing.
*
* <p>
* Derived classes must create {@link ValidatorHandler} objects that have
* <tt>null</tt> {@link ErrorHandler} and
* <tt>null</tt> {@link LSResourceResolver}.
*/
protected ValidatorHandler() {
}
/**
* Sets the {@link ContentHandler} which receives
* the augmented validation result.
*
* <p>
* When a {@link ContentHandler} is specified, a
* {@link ValidatorHandler} will work as a filter
* and basically copy the incoming events to the
* specified {@link ContentHandler}.
*
* <p>
* In doing so, a {@link ValidatorHandler} may modify
* the events, for example by adding defaulted attributes.
*
* <p>
* A {@link ValidatorHandler} may buffer events to certain
* extent, but to allow {@link ValidatorHandler} to be used
* by a parser, the following requirement has to be met.
*
* <ol>
* <li>When
* {@link ContentHandler#startElement(String, String, String, Attributes)},
* {@link ContentHandler#endElement(String, String, String)},
* {@link ContentHandler#startDocument()}, or
* {@link ContentHandler#endDocument()}
* are invoked on a {@link ValidatorHandler},
* the same method on the user-specified {@link ContentHandler}
* must be invoked for the same event before the callback
* returns.
* <li>{@link ValidatorHandler} may not introduce new elements that
* were not present in the input.
*
* <li>{@link ValidatorHandler} may not remove attributes that were
* present in the input.
* </ol>
*
* <p>
* When a callback method on the specified {@link ContentHandler}
* throws an exception, the same exception object must be thrown
* from the {@link ValidatorHandler}. The {@link ErrorHandler}
* should not be notified of such an exception.
*
* <p>
* This method can be called even during a middle of a validation.
*
* @param receiver
* A {@link ContentHandler} or a null value.
*/
public abstract void setContentHandler(ContentHandler receiver);
/**
* Gets the {@link ContentHandler} which receives the
* augmented validation result.
*
* @return
* This method returns the object that was last set through
* the {@link #getContentHandler()} method, or null
* if that method has never been called since this {@link ValidatorHandler}
* has created.
*
* @see #setContentHandler(ContentHandler)
*/
public abstract ContentHandler getContentHandler();
/**
* Sets the {@link ErrorHandler} to receive errors encountered
* during the validation.
*
* <p>
* Error handler can be used to customize the error handling process
* during a validation. When an {@link ErrorHandler} is set,
* errors found during the validation will be first sent
* to the {@link ErrorHandler}.
*
* <p>
* The error handler can abort further validation immediately
* by throwing {@link org.xml.sax.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 {@link ErrorHandler}
*
* <p>
* If any {@link Throwable} is thrown from an {@link ErrorHandler},
* the same {@link Throwable} object will be thrown toward the
* root of the call stack.
*
* <p>
* {@link ValidatorHandler} is not allowed to
* throw {@link org.xml.sax.SAXException} without first reporting it to
* {@link ErrorHandler}.
*
* <p>
* When the {@link ErrorHandler} is null, the implementation will
* behave as if the following {@link ErrorHandler} is set:
* <pre>
* class DraconianErrorHandler implements {@link ErrorHandler} {
* public void fatalError( {@link org.xml.sax.SAXParseException} e ) throws {@link org.xml.sax.SAXException} {
* throw e;
* }
* public void error( {@link org.xml.sax.SAXParseException} e ) throws {@link org.xml.sax.SAXException} {
* throw e;
* }
* public void warning( {@link org.xml.sax.SAXParseException} e ) throws {@link org.xml.sax.SAXException} {
* // noop
* }
* }
* </pre>
*
* <p>
* When a new {@link ValidatorHandler} object is created, initially
* this field is set to null.
*
* @param errorHandler
* A new error handler to be set. This parameter can be null.
*/
public abstract void setErrorHandler(ErrorHandler errorHandler);
/**
* Gets the current {@link ErrorHandler} set to this {@link ValidatorHandler}.
*
* @return
* This method returns the object that was last set through
* the {@link #setErrorHandler(ErrorHandler)} method, or null
* if that method has never been called since this {@link ValidatorHandler}
* has created.
*
* @see #setErrorHandler(ErrorHandler)
*/
public abstract ErrorHandler getErrorHandler();
/**
* Sets the {@link LSResourceResolver} to customize
* resource resolution while in a validation episode.
*
* <p>
* {@link ValidatorHandler} uses a {@link LSResourceResolver}
* when it needs to locate external resources while a validation,
* although exactly what constitutes "locating external resources" is
* up to each schema language.
*
* <p>
* When the {@link LSResourceResolver} is null, the implementation will
* behave as if the following {@link LSResourceResolver} is set:
* <pre>
* class DumbLSResourceResolver implements {@link LSResourceResolver} {
* public {@link org.w3c.dom.ls.LSInput} resolveResource(
* String publicId, String systemId, String baseURI) {
*
* return null; // always return null
* }
* }
* </pre>
*
* <p>
* If a {@link LSResourceResolver} throws a {@link RuntimeException}
* (or instances of its derived classes),
* then the {@link ValidatorHandler} will abort the parsing and
* the caller of the <code>validate</code> method will receive
* the same {@link RuntimeException}.
*
* <p>
* When a new {@link ValidatorHandler} object is created, initially
* this field is set to null.
*
* @param resourceResolver
* A new resource resolver to be set. This parameter can be null.
*/
public abstract void setResourceResolver(LSResourceResolver resourceResolver);
/**
* Gets the current {@link LSResourceResolver} set to this {@link ValidatorHandler}.
*
* @return
* This method returns the object that was last set through
* the {@link #setResourceResolver(LSResourceResolver)} method, or null
* if that method has never been called since this {@link ValidatorHandler}
* has created.
*
* @see #setErrorHandler(ErrorHandler)
*/
public abstract LSResourceResolver getResourceResolver();
/**
* Obtains the {@link TypeInfoProvider} implementation of this
* {@link ValidatorHandler}.
*
* <p>
* The obtained {@link TypeInfoProvider} can be queried during a parse
* to access the type information determined by the validator.
*
* <p>
* 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.
*
* @return
* null if the validator / schema language does not support
* the notion of {@link org.w3c.dom.TypeInfo}.
* Otherwise a non-null valid {@link TypeInfoProvider}.
*/
public abstract TypeInfoProvider getTypeInfoProvider();
/**
* Look up the value of a feature flag.
*
* <p>The feature name is any fully-qualified URI. It is
* possible for a {@link 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.
*
* <p>Implementors are free (and encouraged) to invent their own features,
* using names built on their own URIs.</p>
*
* @param name The feature name, which is a non-null fully-qualified URI.
* @return The current value of the feature (true or false).
* @exception org.xml.sax.SAXNotRecognizedException If the feature
* value can't be assigned or retrieved.
* @exception org.xml.sax.SAXNotSupportedException When the
* {@link ValidatorHandler} recognizes the feature name but
* cannot determine its value at this time.
* @throws NullPointerException
* When the name parameter is null.
* @see #setFeature(String, boolean)
*/
public boolean getFeature(String name) throws SAXNotRecognizedException, SAXNotSupportedException {
if(name==null)
throw new NullPointerException();
throw new SAXNotRecognizedException(name);
}
/**
* Set the value of a feature flag.
*
* <p>
* Feature can be used to control the way a {@link ValidatorHandler}
* parses schemas, although {@link ValidatorHandler}s are not required
* to recognize any specific property names.</p>
*
* <p>The feature name is any fully-qualified URI. It is
* possible for a {@link 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.</p>
*
* @param name The feature name, which is a non-null fully-qualified URI.
* @param value The requested value of the feature (true or false).
*
* @exception org.xml.sax.SAXNotRecognizedException If the feature
* value can't be assigned or retrieved.
* @exception org.xml.sax.SAXNotSupportedException When the
* {@link ValidatorHandler} recognizes the feature name but
* cannot set the requested value.
* @throws NullPointerException
* When the name parameter is null.
*
* @see #getFeature(String)
*/
public void setFeature(String name, boolean value) throws SAXNotRecognizedException, SAXNotSupportedException {
if(name==null)
throw new NullPointerException();
throw new SAXNotRecognizedException(name);
}
/**
* Set the value of a property.
*
* <p>The property name is any fully-qualified URI. It is
* possible for a {@link 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.</p>
*
* <p>{@link ValidatorHandler}s are not required to recognize setting
* any specific property names.</p>
*
* @param name The property name, which is a non-null fully-qualified URI.
* @param object The requested value for the property.
*
* @exception org.xml.sax.SAXNotRecognizedException If the property
* value can't be assigned or retrieved.
* @exception org.xml.sax.SAXNotSupportedException When the
* {@link ValidatorHandler} recognizes the property name but
* cannot set the requested value.
* @throws NullPointerException
* When the name parameter is null.
*/
public void setProperty(String name, Object object) throws SAXNotRecognizedException, SAXNotSupportedException {
if(name==null)
throw new NullPointerException();
throw new SAXNotRecognizedException(name);
}
/**
* Look up the value of a property.
*
* <p>The property name is any fully-qualified URI. It is
* possible for a {@link 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.</p>
*
* <p>{@link ValidatorHandler}s are not required to recognize any specific
* property names.</p>
*
* <p>Implementors are free (and encouraged) to invent their own properties,
* using names built on their own URIs.</p>
*
* @param name The property name, which is a non-null fully-qualified URI.
* @return The current value of the property.
* @exception org.xml.sax.SAXNotRecognizedException If the property
* value can't be assigned or retrieved.
* @exception org.xml.sax.SAXNotSupportedException When the
* XMLReader recognizes the property name but
* cannot determine its value at this time.
* @throws NullPointerException
* When the name parameter is null.
* @see #setProperty(String, Object)
*/
public Object getProperty(String name) throws SAXNotRecognizedException, SAXNotSupportedException {
if(name==null)
throw new NullPointerException();
throw new SAXNotRecognizedException(name);
}
}