Java tutorial
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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; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.xerces.dom.ElementImpl; import org.chiba.xml.ns.NamespaceConstants; import org.chiba.xml.xforms.config.Config; import org.chiba.xml.xforms.config.XFormsConfigException; import org.chiba.xml.xforms.core.Model; import org.chiba.xml.xforms.exception.XFormsException; import org.w3c.dom.Element; import java.util.Collections; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; /** * CustomElementFactory creates objects for all elements in the input Document * that match a namespace/element name retrieved from the configuration. * * @author <a href="mailto:flaviocosta@users.sourceforge.net">Flavio Costa </a> */ public class CustomElementFactory implements XFormsConstants { /** * The logger. */ private static final Log LOGGER = LogFactory.getLog(Config.class); /** * Holds the configuration for custom elements. */ private static final Map ELEMENTS = getCustomElementsConfig(); private static final Map ACTIONS_ELEMENTS = getCustomActionElementsConfig(); /** * Used to quickly check if there are custom elements or not. */ private boolean noCustomElements; /** * Loads the configuration for custom elements. * * @return A Map where the keys are in the format namespace-uri:element-name * and the value is the reference to the class that implements the * custom element, or an empty map if the configuration could not be * loaded for some reason. */ private static Map getCustomElementsConfig() { try { Map elementClassNames = Config.getInstance().getCustomElements(); Map elementClassRefs = new HashMap(elementClassNames.size()); Iterator itr = elementClassNames.entrySet().iterator(); //converts class names into the class references while (itr.hasNext()) { Map.Entry entry = (Entry) itr.next(); String key = (String) entry.getKey(); String className = (String) entry.getValue(); Class classRef = Class.forName(className); elementClassRefs.put(key, classRef); } //return the configuration return elementClassRefs; } catch (XFormsConfigException xfce) { LOGGER.error("could not load custom-elements config: " + xfce.getMessage()); } catch (ClassNotFoundException cnfe) { LOGGER.error("class configured for custom-element not found: " + cnfe.getMessage()); } //returns an empty map (no custom elements) return Collections.EMPTY_MAP; } private static Map getCustomActionElementsConfig() { try { Map elementClassNames = Config.getInstance().getCustomActionsElements(); Map elementClassRefs = new HashMap(elementClassNames.size()); Iterator itr = elementClassNames.entrySet().iterator(); //converts class names into the class references while (itr.hasNext()) { Map.Entry entry = (Entry) itr.next(); String key = (String) entry.getKey(); String className = (String) entry.getValue(); Class classRef = Class.forName(className); elementClassRefs.put(key, classRef); } //return the configuration return elementClassRefs; } catch (XFormsConfigException xfce) { LOGGER.error("could not load custom-elements config: " + xfce.getMessage()); } catch (ClassNotFoundException cnfe) { LOGGER.error("class configured for custom-element not found: " + cnfe.getMessage()); } //returns an empty map (no custom elements) return Collections.EMPTY_MAP; } /** * Creates a new CustomElementFactory object. */ public CustomElementFactory() throws XFormsException { this.noCustomElements = ELEMENTS.isEmpty() && ACTIONS_ELEMENTS.isEmpty(); } /** * Given an element, generate a key used to find objects in ELEMENTS. * * @param element * Element whose configuration is to be looked for. * * @return The key corresponding to the element definition. */ public String getKeyForElement(Element element) { return element.getNamespaceURI() + ":" + element.getLocalName(); } /** * Returns true if the given DOM Element matches a configured custom * element. * * @param element * The DOM Element to investigate. * @return Whether the element matches a custom element or not. * * @throws XFormsException * In case of MustUnderstand Module failure. */ public boolean isCustomElement(Element element) throws XFormsException { if (this.noCustomElements) { //no custom elements configured return false; } //key to search the Map for a custom element String key = getKeyForElement(element); if (ELEMENTS.containsKey(key)) { //a match was found return true; } //if the element is not recognized but it has a //mustUnderstand attribute, throw an exception to //signal error according to the spec if (element.hasAttributeNS(NamespaceConstants.XFORMS_NS, MUST_UNDERSTAND_ATTRIBUTE)) { String elementId = element.getPrefix() + ":" + element.getLocalName(); throw new XFormsException("MustUnderstand Module failure at element " + elementId); } //no matching configuration was found return false; } public boolean isCustomActionElement(Element element) throws XFormsException { if (this.noCustomElements) { //no custom elements configured return false; } //key to search the Map for a custom element String key = getKeyForElement(element); if (ACTIONS_ELEMENTS.containsKey(key)) { //a match was found return true; } //if the element is not recognized but it has a //mustUnderstand attribute, throw an exception to //signal error according to the spec if (element.hasAttributeNS(NamespaceConstants.XFORMS_NS, MUST_UNDERSTAND_ATTRIBUTE)) { String elementId = element.getPrefix() + ":" + element.getLocalName(); throw new XFormsException("MustUnderstand Module failure at element " + elementId); } //no matching configuration was found return false; } /** * Factory method for custom element implementations. * * @param element * The DOM Element which will be annotated. * @param model * The owning model. * @return The created object. */ public XFormsElement createCustomXFormsElement(Element element, Model model) throws XFormsException { //gets the class reference String key = getKeyForElement(element); final Class elementClazz; if (ELEMENTS.containsKey(key)) { elementClazz = (Class) ELEMENTS.get(key); } else { elementClazz = (Class) ACTIONS_ELEMENTS.get(key); } //this should never happen if (elementClazz == null) { throw new XFormsException("No class defined for " + key); } XFormsElement xformsElement = null; if (elementClazz != null) { try { //initializes a new object from the class xformsElement = (XFormsElement) elementClazz .getConstructor(new Class[] { Element.class, Model.class }) .newInstance(new Object[] { (Element) element, model }); } catch (Exception e) { throw new XFormsException(e); } ((ElementImpl) element).setUserData(xformsElement); } return xformsElement; } }