/**
* Copyright 2005-2014 Restlet
*
* The contents of this file are subject to the terms of one of the following
* open source licenses: Apache 2.0 or or EPL 1.0 (the "Licenses"). You can
* select the license that you prefer but you may not use this file except in
* compliance with one of these Licenses.
*
* You can obtain a copy of the Apache 2.0 license at
* http://www.opensource.org/licenses/apache-2.0
*
* You can obtain a copy of the EPL 1.0 license at
* http://www.opensource.org/licenses/eclipse-1.0
*
* See the Licenses for the specific language governing permissions and
* limitations under the Licenses.
*
* Alternatively, you can obtain a royalty free commercial license with less
* limitations, transferable or non-transferable, directly at
* http://restlet.com/products/restlet-framework
*
* Restlet is a registered trademark of Restlet S.A.S.
*/
package org.restlet.ext.xml;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import org.restlet.Request;
import org.restlet.Response;
import org.restlet.data.CharacterSet;
import org.restlet.data.Encoding;
import org.restlet.data.Language;
import org.restlet.data.MediaType;
import org.restlet.representation.Representation;
import org.restlet.routing.Filter;
/**
* Filter that can transform XML representations by applying an XSLT transform
* sheet. It uses the {@link org.restlet.representation.TransformRepresentation}
* to actually transform the XML entities.<br>
* <br>
* Concurrency note: instances of this class or its subclasses can be invoked by
* several threads at the same time and therefore must be thread-safe. You
* should be especially careful when storing state in member variables.
*
* @author Jerome Louvel
*/
public class Transformer extends Filter {
/**
* Mode that transforms request entities before their handling by the
* attached Restlet.
*/
public static final int MODE_REQUEST = 1;
/**
* Mode that transforms response entities after their handling by the
* attached Restlet.
*/
public static final int MODE_RESPONSE = 2;
/** The transformation mode. */
private volatile int mode;
/**
* The character set of the result representation. The default value is
* null.
*/
private volatile CharacterSet resultCharacterSet;
/**
* The encodings of the result representation.
*/
private volatile List<Encoding> resultEncodings;
/** The languages of the result representation. */
private volatile List<Language> resultLanguages;
/**
* The media type of the result representation. MediaType.APPLICATION_XML by
* default.
*/
private volatile MediaType resultMediaType;
/** The XSLT transform sheet to apply to message entities. */
private volatile Representation transformSheet;
/**
* Constructor.
*
* @param mode
* The transformation mode.
* @param transformSheet
* The XSLT transform sheet to apply to message entities.
*/
public Transformer(int mode, Representation transformSheet) {
this.mode = mode;
this.transformSheet = transformSheet;
this.resultMediaType = MediaType.APPLICATION_XML;
this.resultCharacterSet = null;
}
@Override
protected void afterHandle(Request request, Response response) {
if ((getMode() == MODE_RESPONSE) && canTransform(response.getEntity())) {
response.setEntity(transform(response.getEntity()));
}
}
@Override
protected int beforeHandle(Request request, Response response) {
if ((getMode() == MODE_REQUEST) && canTransform(request.getEntity())) {
request.setEntity(transform(request.getEntity()));
}
return CONTINUE;
}
/**
* Indicates if the filter can transform the given message entity. By
* default, it always returns true.
*
* @param representation
* The entity representation to test.
* @return True if the transformation can be applied.
*/
protected boolean canTransform(Representation representation) {
return true;
}
/**
* Returns the transformation mode. See MODE_* constants.
*
* @return The transformation mode.
*/
public int getMode() {
return this.mode;
}
/**
* Returns the character set of the result representation. The default value
* is null.
*
* @return The character set of the result representation.
*/
public CharacterSet getResultCharacterSet() {
return this.resultCharacterSet;
}
/**
* Returns the modifiable list of encodings of the result representation.
*
* @return The encoding of the result representation.
*/
public List<Encoding> getResultEncodings() {
// Lazy initialization with double-check.
List<Encoding> re = this.resultEncodings;
if (re == null) {
synchronized (this) {
re = this.resultEncodings;
if (re == null) {
this.resultEncodings = re = new CopyOnWriteArrayList<Encoding>();
}
}
}
return re;
}
/**
* Returns the modifiable list of languages of the result representation.
*
* @return The language of the result representation.
*/
public List<Language> getResultLanguages() {
// Lazy initialization with double-check.
List<Language> v = this.resultLanguages;
if (v == null) {
synchronized (this) {
v = this.resultLanguages;
if (v == null) {
this.resultLanguages = v = new CopyOnWriteArrayList<Language>();
}
}
}
return v;
}
/**
* Returns the media type of the result representation. The default value is
* MediaType.APPLICATION_XML.
*
* @return The media type of the result representation.
*/
public MediaType getResultMediaType() {
return this.resultMediaType;
}
/**
* Returns the XSLT transform sheet to apply to message entities.
*
* @return The XSLT transform sheet to apply to message entities.
*/
public Representation getTransformSheet() {
return this.transformSheet;
}
/**
* Sets the transformation mode. See MODE_* constants.
*
* @param mode
* The transformation mode.
*/
public void setMode(int mode) {
this.mode = mode;
}
/**
* Sets the character set of the result representation.
*
* @param resultCharacterSet
* The character set of the result representation.
*/
public void setResultCharacterSet(CharacterSet resultCharacterSet) {
this.resultCharacterSet = resultCharacterSet;
}
/**
* Sets the encodings of the result representation.
*
* @param resultEncodings
* The encodings of the result representation.
*/
public void setResultEncodings(List<Encoding> resultEncodings) {
this.resultEncodings = resultEncodings;
}
/**
* Sets the languages of the result representation.
*
* @param resultLanguages
* The languages of the result representation.
*/
public void setResultLanguages(List<Language> resultLanguages) {
this.resultLanguages = resultLanguages;
}
/**
* Sets the media type of the result representation.
*
* @param resultMediaType
* The media type of the result representation.
*/
public void setResultMediaType(MediaType resultMediaType) {
this.resultMediaType = resultMediaType;
}
/**
* Sets the XSLT transform sheet to apply to message entities.
*
* @param transformSheet
* The XSLT transform sheet to apply to message entities.
*/
public void setTransformSheet(Representation transformSheet) {
this.transformSheet = transformSheet;
}
/**
* Transforms a source XML representation by applying an XSLT transform
* sheet to it.
*
* @param source
* The source XML representation.
* @return The generated result representation.
*/
public Representation transform(Representation source) {
final Representation result = new TransformRepresentation(getContext(),
source, getTransformSheet());
if (this.resultLanguages != null) {
result.getLanguages().addAll(getResultLanguages());
}
result.setCharacterSet(getResultCharacterSet());
if (this.resultEncodings != null) {
result.getEncodings().addAll(getResultEncodings());
}
result.setMediaType(getResultMediaType());
return result;
}
}