Java tutorial
/* * 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 * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.xml.transform; import java.util.Properties; /** * 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 Jeff Suttor * @since 1.4 */ public abstract class Transformer { /** * Default constructor is protected on purpose. */ protected Transformer() { } /** * <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() + "\""); } /** * <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. * * <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 <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.</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. * * <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. */ public abstract void clearParameters(); /** * 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(). * * @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. * * <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 <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.</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); /** * <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. * * <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 <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.</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; /** * <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. * * @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. * * @return The current error handler, which should never be null. */ public abstract ErrorListener getErrorListener(); }