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 * Copyright (c) 2000, 2005, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package javax.xml.transform;

import java.util.Properties;


An instance of this abstract class can transform a
source tree into a result tree.

An instance of this class can be obtained with the TransformerFactory.newTransformer method. This instance may then be used to process XML from a variety of sources and write the transformation output to a variety of sinks.


An object of this class may not be used in multiple threads
running concurrently.  Different Transformers may be used
concurrently by different threads.


A Transformer may be used multiple times.  Parameters and
output properties are preserved across transformations.


Author:Jeff Suttor
Since:1.4
/**
 * An instance of this abstract class can transform a
 * source tree into a result tree.
 *
 * <p>An instance of this class can be obtained with the
 * {@link TransformerFactory#newTransformer TransformerFactory.newTransformer}
 * method. This instance may then be used to process XML from a
 * variety of sources and write the transformation output to a
 * variety of sinks.</p>
 *
 * <p>An object of this class may not be used in multiple threads
 * running concurrently.  Different Transformers may be used
 * concurrently by different threads.</p>
 *
 * <p>A <code>Transformer</code> may be used multiple times.  Parameters and
 * output properties are preserved across transformations.</p>
 *
 * @author <a href="Jeff.Suttor@Sun.com">Jeff Suttor</a>
 * @since 1.4
 */
public abstract class Transformer {

    
Default constructor is protected on purpose.

/**
     * Default constructor is protected on purpose.
     */
    protected Transformer() { }

        
Reset this Transformer to its original configuration.


Transformer is reset to the same state as when it was created with TransformerFactory.newTransformer(), TransformerFactory.newTransformer(Source source) or Templates.newTransformer(). reset() is designed to allow the reuse of existing Transformers
thus saving resources associated with the creation of new Transformers.


The reset Transformer is not guaranteed to have the same URIResolver or ErrorListener Objects, e.g. Object.equals(Object obj). It is guaranteed to have a functionally equal URIResolver
and ErrorListener.


Throws:
Since:1.5
/**
         * <p>Reset this <code>Transformer</code> to its original configuration.</p>
         *
         * <p><code>Transformer</code> is reset to the same state as when it was created with
         * {@link TransformerFactory#newTransformer()},
         * {@link TransformerFactory#newTransformer(Source source)} or
         * {@link Templates#newTransformer()}.
         * <code>reset()</code> is designed to allow the reuse of existing <code>Transformer</code>s
         * thus saving resources associated with the creation of new <code>Transformer</code>s.</p>
         *
         * <p>The reset <code>Transformer</code> is not guaranteed to have the same {@link URIResolver}
         * or {@link ErrorListener} <code>Object</code>s, e.g. {@link Object#equals(Object obj)}.
         * It is guaranteed to have a functionally equal <code>URIResolver</code>
         * and <code>ErrorListener</code>.</p>
     *
     * @throws UnsupportedOperationException When implementation does not
     *   override this method.
         *
         * @since 1.5
         */
        public void reset() {

                // implementors should override this method
                throw new UnsupportedOperationException(
                        "This Transformer, \"" + this.getClass().getName() + "\", does not support the reset functionality."
                        + "  Specification \"" + this.getClass().getPackage().getSpecificationTitle() + "\""
                        + " version \"" + this.getClass().getPackage().getSpecificationVersion() + "\""
                        );
        }

    
Transform the XML Source to a Result.
Specific transformation behavior is determined by the settings of the
TransformerFactory in effect when the
Transformer was instantiated and any modifications made to
the Transformer instance.


An empty Source is represented as an empty document as constructed by DocumentBuilder.newDocument(). The result of transforming an empty Source depends on
the transformation behavior; it is not always an empty
Result.


Params:
  • xmlSource – The XML input to transform.
  • outputTarget – The Result of transforming the
  xmlSource.
Throws:
/**
     * <p>Transform the XML <code>Source</code> to a <code>Result</code>.
     * Specific transformation behavior is determined by the settings of the
     * <code>TransformerFactory</code> in effect when the
     * <code>Transformer</code> was instantiated and any modifications made to
     * the <code>Transformer</code> instance.</p>
     *
     * <p>An empty <code>Source</code> is represented as an empty document
     * as constructed by {@link javax.xml.parsers.DocumentBuilder#newDocument()}.
     * The result of transforming an empty <code>Source</code> depends on
     * the transformation behavior; it is not always an empty
     * <code>Result</code>.</p>
     *
     * @param xmlSource The XML input to transform.
     * @param outputTarget The <code>Result</code> of transforming the
     *   <code>xmlSource</code>.
     *
     * @throws TransformerException If an unrecoverable error occurs
     *   during the course of the transformation.
     */
    public abstract void transform(Source xmlSource, Result outputTarget)
        throws TransformerException;

    
Add a parameter for the transformation.

Pass a qualified name as a two-part string, the namespace URI
enclosed in curly braces ({}), followed by the local name. If the
name has a null URL, the String only contain the local name. An
application can safely check for a non-null URI by testing to see if the
first character of the name is a '{' character.


For example, if a URI and local name were obtained from an element
defined with <xyz:foo
xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,
then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
Note that no prefix is used.


Params:
  • name – The name of the parameter, which may begin with a
namespace URI in curly braces ({}).
  • value – The value object.  This can be any valid Java object. It is
up to the processor to provide the proper object coersion or to simply
pass the object on for use in an extension.
Throws:
/**
     * Add a parameter for the transformation.
     *
     * <p>Pass a qualified name as a two-part string, the namespace URI
     * enclosed in curly braces ({}), followed by the local name. If the
     * name has a null URL, the String only contain the local name. An
     * application can safely check for a non-null URI by testing to see if the
     * first character of the name is a '{' character.</p>
     * <p>For example, if a URI and local name were obtained from an element
     * defined with &lt;xyz:foo
     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
     * Note that no prefix is used.</p>
     *
     * @param name The name of the parameter, which may begin with a
     * namespace URI in curly braces ({}).
     * @param value The value object.  This can be any valid Java object. It is
     * up to the processor to provide the proper object coersion or to simply
     * pass the object on for use in an extension.
     *
     * @throws NullPointerException If value is null.
     */
     public abstract void setParameter(String name, Object value);

    
Get a parameter that was explicitly set with setParameter.

This method does not return a default parameter value, which
cannot be determined until the node context is evaluated during
the transformation process.

Params:
  • name – of Object to get
Returns:A parameter that has been set with setParameter.
/**
     * Get a parameter that was explicitly set with setParameter.
     *
     * <p>This method does not return a default parameter value, which
     * cannot be determined until the node context is evaluated during
     * the transformation process.
     *
     * @param name of <code>Object</code> to get
     *
     * @return A parameter that has been set with setParameter.
     */
    public abstract Object getParameter(String name);

    /**
     * <p>Set a list of parameters.</p>
     *
     * <p>Note that the list of parameters is specified as a
     * <code>Properties</code> <code>Object</code> which limits the parameter
     * values to <code>String</code>s.  Multiple calls to
     * {@link #setParameter(String name, Object value)} should be used when the
     * desired values are non-<code>String</code> <code>Object</code>s.
     * The parameter names should conform as specified in
     * {@link #setParameter(String name, Object value)}.
     * An <code>IllegalArgumentException</code> is thrown if any names do not
     * conform.</p>
     *
     * <p>New parameters in the list are added to any existing parameters.
     * If the name of a new parameter is equal to the name of an existing
     * parameter as determined by {@link java.lang.Object#equals(Object obj)},
     *  the existing parameter is set to the new value.</p>
     *
     * @param params Parameters to set.
     *
     * @throws IllegalArgumentException If any parameter names do not conform
     *   to the naming rules.
     */

    
Clear all parameters set with setParameter.

/**
     * Clear all parameters set with setParameter.
     */
    public abstract void clearParameters();

    
Set an object that will be used to resolve URIs used in
document().

If the resolver argument is null, the URIResolver value will
be cleared and the transformer will no longer have a resolver.


Params:
  • resolver – An object that implements the URIResolver interface,
or null.
/**
     * Set an object that will be used to resolve URIs used in
     * document().
     *
     * <p>If the resolver argument is null, the URIResolver value will
     * be cleared and the transformer will no longer have a resolver.</p>
     *
     * @param resolver An object that implements the URIResolver interface,
     * or null.
     */
    public abstract void setURIResolver(URIResolver resolver);

    
Get an object that will be used to resolve URIs used in
document().

Returns:An object that implements the URIResolver interface,
or null.
/**
     * Get an object that will be used to resolve URIs used in
     * document().
     *
     * @return An object that implements the URIResolver interface,
     * or null.
     */
    public abstract URIResolver getURIResolver();

    
Set the output properties for the transformation.  These
properties will override properties set in the Templates
with xsl:output.

If argument to this function is null, any properties
previously set are removed, and the value will revert to the value
defined in the templates object.


Pass a qualified property key name as a two-part string, the namespace
URI enclosed in curly braces ({}), followed by the local name. If the
name has a null URL, the String only contain the local name. An
application can safely check for a non-null URI by testing to see if the
first character of the name is a '{' character.


For example, if a URI and local name were obtained from an element
defined with <xyz:foo
xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,
then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
Note that no prefix is used.

An IllegalArgumentException is thrown  if any of the
argument keys are not recognized and are not namespace qualified.

Params:
  • oformat – A set of output properties that will be
  used to override any of the same properties in affect
  for the transformation.
Throws:
See Also:
/**
     * Set the output properties for the transformation.  These
     * properties will override properties set in the Templates
     * with xsl:output.
     *
     * <p>If argument to this function is null, any properties
     * previously set are removed, and the value will revert to the value
     * defined in the templates object.</p>
     *
     * <p>Pass a qualified property key name as a two-part string, the namespace
     * URI enclosed in curly braces ({}), followed by the local name. If the
     * name has a null URL, the String only contain the local name. An
     * application can safely check for a non-null URI by testing to see if the
     * first character of the name is a '{' character.</p>
     * <p>For example, if a URI and local name were obtained from an element
     * defined with &lt;xyz:foo
     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
     * Note that no prefix is used.</p>
     * An <code>IllegalArgumentException</code> is thrown  if any of the
     * argument keys are not recognized and are not namespace qualified.
     *
     * @param oformat A set of output properties that will be
     *   used to override any of the same properties in affect
     *   for the transformation.
     *
     * @throws IllegalArgumentException When keys are not recognized and
     *   are not namespace qualified.
     *
     * @see javax.xml.transform.OutputKeys
     * @see java.util.Properties
     *
     */
    public abstract void setOutputProperties(Properties oformat);

    
Get a copy of the output properties for the transformation.


The properties returned should contain properties set by the user,
and properties set by the stylesheet, and these properties
are "defaulted" by default properties specified by
section 16 of the
XSL Transformations (XSLT) W3C Recommendation. The properties that were specifically set by the user or the stylesheet should be in the base Properties list, while the XSLT default properties that were not specifically set should be the default Properties list. Thus, getOutputProperties().getProperty(String key) will obtain any property in that was set by setOutputProperty, setOutputProperties, in the stylesheet, or the default properties, while getOutputProperties().get(String key) will only retrieve properties that were explicitly set by setOutputProperty, setOutputProperties, or in the stylesheet.


Note that mutation of the Properties object returned will not
effect the properties that the transformer contains.


If any of the argument keys are not recognized and are not namespace qualified, the property will be ignored and not returned. In other words the behaviour is not orthogonal with setOutputProperties.


See Also:
Returns:A copy of the set of output properties in effect for
  the next transformation.
/**
     * <p>Get a copy of the output properties for the transformation.</p>
     *
     * <p>The properties returned should contain properties set by the user,
     * and properties set by the stylesheet, and these properties
     * are "defaulted" by default properties specified by
     * <a href="http://www.w3.org/TR/xslt#output">section 16 of the
     * XSL Transformations (XSLT) W3C Recommendation</a>.  The properties that
     * were specifically set by the user or the stylesheet should be in the base
     * Properties list, while the XSLT default properties that were not
     * specifically set should be the default Properties list.  Thus,
     * getOutputProperties().getProperty(String key) will obtain any
     * property in that was set by {@link #setOutputProperty},
     * {@link #setOutputProperties}, in the stylesheet, <em>or</em> the default
     * properties, while
     * getOutputProperties().get(String key) will only retrieve properties
     * that were explicitly set by {@link #setOutputProperty},
     * {@link #setOutputProperties}, or in the stylesheet.</p>
     *
     * <p>Note that mutation of the Properties object returned will not
     * effect the properties that the transformer contains.</p>
     *
     * <p>If any of the argument keys are not recognized and are not
     * namespace qualified, the property will be ignored and not returned.
     * In other words the behaviour is not orthogonal with
     * {@link #setOutputProperties setOutputProperties}.</p>
     *
     * @return A copy of the set of output properties in effect for
     *   the next transformation.
     *
     * @see javax.xml.transform.OutputKeys
     * @see java.util.Properties
     * @see <a href="http://www.w3.org/TR/xslt#output">
     *   XSL Transformations (XSLT) Version 1.0</a>
     */
    public abstract Properties getOutputProperties();

    
Set an output property that will be in effect for the
transformation.

Pass a qualified property name as a two-part string, the namespace URI
enclosed in curly braces ({}), followed by the local name. If the
name has a null URL, the String only contain the local name. An
application can safely check for a non-null URI by testing to see if the
first character of the name is a '{' character.


For example, if a URI and local name were obtained from an element
defined with <xyz:foo
xmlns:xyz="http://xyz.foo.com/yada/baz.html"/>,
then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
Note that no prefix is used.


The Properties object that was passed to setOutputProperties won't be effected by calling this method.


Params:
  • name – A non-null String that specifies an output
property name, which may be namespace qualified.
  • value – The non-null string value of the output property.
Throws:
See Also:
/**
     * Set an output property that will be in effect for the
     * transformation.
     *
     * <p>Pass a qualified property name as a two-part string, the namespace URI
     * enclosed in curly braces ({}), followed by the local name. If the
     * name has a null URL, the String only contain the local name. An
     * application can safely check for a non-null URI by testing to see if the
     * first character of the name is a '{' character.</p>
     * <p>For example, if a URI and local name were obtained from an element
     * defined with &lt;xyz:foo
     * xmlns:xyz="http://xyz.foo.com/yada/baz.html"/&gt;,
     * then the qualified name would be "{http://xyz.foo.com/yada/baz.html}foo".
     * Note that no prefix is used.</p>
     *
     * <p>The Properties object that was passed to {@link #setOutputProperties}
     * won't be effected by calling this method.</p>
     *
     * @param name A non-null String that specifies an output
     * property name, which may be namespace qualified.
     * @param value The non-null string value of the output property.
     *
     * @throws IllegalArgumentException If the property is not supported, and is
     * not qualified with a namespace.
     *
     * @see javax.xml.transform.OutputKeys
     */
    public abstract void setOutputProperty(String name, String value)
        throws IllegalArgumentException;

    
Get an output property that is in effect for the transformer.


If a property has been set using setOutputProperty, that value will be returned. Otherwise, if a property is explicitly specified in the stylesheet, that value will be returned. If the value of the property has been defaulted, that is, if no value has been set explicitly either with setOutputProperty or in the stylesheet, the result may vary depending on implementation and input stylesheet.


Params:
  • name – A non-null String that specifies an output
property name, which may be namespace qualified.
Throws:
See Also:
Returns:The string value of the output property, or null
if no property was found.
/**
     * <p>Get an output property that is in effect for the transformer.</p>
     *
     * <p>If a property has been set using {@link #setOutputProperty},
     * that value will be returned. Otherwise, if a property is explicitly
     * specified in the stylesheet, that value will be returned. If
     * the value of the property has been defaulted, that is, if no
     * value has been set explicitly either with {@link #setOutputProperty} or
     * in the stylesheet, the result may vary depending on
     * implementation and input stylesheet.</p>
     *
     * @param name A non-null String that specifies an output
     * property name, which may be namespace qualified.
     *
     * @return The string value of the output property, or null
     * if no property was found.
     *
     * @throws IllegalArgumentException If the property is not supported.
     *
     * @see javax.xml.transform.OutputKeys
     */
    public abstract String getOutputProperty(String name)
        throws IllegalArgumentException;

    
Set the error event listener in effect for the transformation.

Params:
  • listener – The new error listener.
Throws:
/**
     * Set the error event listener in effect for the transformation.
     *
     * @param listener The new error listener.
     *
     * @throws IllegalArgumentException if listener is null.
     */
    public abstract void setErrorListener(ErrorListener listener)
        throws IllegalArgumentException;

    
Get the error event handler in effect for the transformation.
Implementations must provide a default error listener.

Returns:The current error handler, which should never be null.
/**
     * Get the error event handler in effect for the transformation.
     * Implementations must provide a default error listener.
     *
     * @return The current error handler, which should never be null.
     */
    public abstract ErrorListener getErrorListener();
}