Java tutorial
// Copyright 2006 Chibacon /* * * Artistic License * * Preamble * * The intent of this document is to state the conditions under which a Package may be copied, such that * the Copyright Holder maintains some semblance of artistic control over the development of the * package, while giving the users of the package the right to use and distribute the Package in a * more-or-less customary fashion, plus the right to make reasonable modifications. * * Definitions: * * "Package" refers to the collection of files distributed by the Copyright Holder, and derivatives * of that collection of files created through textual modification. * * "Standard Version" refers to such a Package if it has not been modified, or has been modified * in accordance with the wishes of the Copyright Holder. * * "Copyright Holder" is whoever is named in the copyright or copyrights for the package. * * "You" is you, if you're thinking about copying or distributing this Package. * * "Reasonable copying fee" is whatever you can justify on the basis of media cost, duplication * charges, time of people involved, and so on. 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THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF * MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE. * */ package org.chiba.xml.xforms.xpath; import org.apache.commons.jxpath.Function; import org.apache.commons.jxpath.Functions; import org.apache.commons.jxpath.functions.MethodFunction; import org.apache.commons.jxpath.util.MethodLookupUtils; import org.chiba.xml.ns.NamespaceConstants; import org.chiba.xml.ns.NamespaceResolver; import org.chiba.xml.xforms.config.Config; import org.w3c.dom.Element; import java.lang.reflect.Method; import java.util.HashSet; import java.util.Set; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; /** * Provides namespace based access to extension function implementations. Checks for user-defined * functions in default.xml config-file, core XForms functions and extensions provided only * by Chiba. * * Todo: Refactor function name mapping, allow function libraries. * * @author Joern Turner * @author Terence Jacyno * @version $Id: ExtensionFunctions.java,v 1.1 2009/02/17 09:00:54 civilis Exp $ */ public class ExtensionFunctions implements Functions { private static final Log LOGGER = LogFactory.getLog(ExtensionFunctions.class); private Element namespaceContext = null; private Set namespaces = null; public ExtensionFunctions() { this.namespaces = new HashSet(); } /** * Sets the namespace context element. * * @param namespaceContext the namespace context element. */ public void setNamespaceContext(Element namespaceContext) { this.namespaceContext = namespaceContext; } public Set getUsedNamespaces() { return namespaces; } /** * implementation of JXPath Functions interface. Responsible for loading XPath extension functions in JXPath. * @param prefix the namespace URI of the function * @param name the name of the function * @param parameters array of parameters for function * @return the Function object for use within JXPath evaluation */ public Function getFunction(String prefix, String name, Object[] parameters) { // lookup namespace uri String uri = null; if (prefix != null) { uri = NamespaceResolver.getNamespaceURI(this.namespaceContext, prefix); this.namespaces.add(uri); } // check xforms namespace if (uri == null || NamespaceConstants.XFORMS_NS.equals(uri)) { Class clazz = org.chiba.xml.xforms.xpath.XFormsExtensionFunctions.class; // map names if (name.equals("if")) { return getMethodFunction(clazz, "IF", parameters); } //auto-mapping when the name contains '-' //(added by Flavio Costa) if (name.indexOf('-') > -1) { return getMethodFunction(clazz, name.replace('-', '_'), parameters); } return getMethodFunction(clazz, name, parameters); } // check chiba namespace if (NamespaceConstants.CHIBA_NS.equals(uri)) { // check core function which don't need to be declared MethodFunction methodFunction = getMethodFunction(CoreExtensionFunctions.class, name, parameters); if (methodFunction != null) { return methodFunction; } } // ==================== Added by Terence Jacyno (start): 7.12 - extension functions // check user-defined functions try { String[] functionInfo = Config.getInstance().getExtensionFunction((uri == null) ? prefix : uri, name); if (functionInfo != null) { Class clazz = Class.forName(functionInfo[0]); Function function = getMethodFunction(clazz, functionInfo[1], parameters); if (LOGGER.isDebugEnabled()) { LOGGER.debug("functionInfo:: function name: " + functionInfo[1] + ":: java class: " + functionInfo[0]); for (int i = 0; i < parameters.length; i++) { LOGGER.debug("parameter: " + parameters[i]); } } if (function != null) { return function; } } } catch (Exception ex) { LOGGER.error("An error occured while loading XPath extension function: " + prefix + ":" + name); //ignore for now } // ==================== Added by Terence Jacyno (end): 7.12 - extension functions return null; } private MethodFunction getMethodFunction(Class clazz, String name, Object[] parameters) { Method method = MethodLookupUtils.lookupStaticMethod(clazz, name, parameters); if (method != null) { return new MethodFunction(method); } return null; } } // end of class