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.connector.context; import org.apache.commons.jxpath.JXPathContext; import org.apache.commons.jxpath.JXPathException; import org.apache.commons.jxpath.Pointer; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.chiba.xml.xforms.connector.AbstractConnector; import org.chiba.xml.xforms.connector.URIResolver; import org.chiba.xml.xforms.exception.XFormsException; import java.net.URI; /** * The Context Resolver performs a lookup in Chiba's context map and returns * the object denoted by the scheme specific part of the resolver's URI. * <p/> * This resolver uses an opaque URI, i.e. use <code>context:document</code> * or <code>context:/document</code> as URI in order to access the * <code>document</code> context property. Nested properties are supported too, * e.g. <code>context:deep/nested/document</code> is perfectly legal as long as * such a nested property exists in Chiba's context. * <p/> * No checks are performed wether the context property is a DOM Node. An attempt * to access a non-existing property will result in an exception. * * @author Joern Turner * @author Ulrich Nicolas Lissé * @version $Id: ContextResolver.java,v 1.1 2009/02/17 09:00:54 civilis Exp $ */ public class ContextResolver extends AbstractConnector implements URIResolver { /** * The logger. */ private static Log LOGGER = LogFactory.getLog(ContextResolver.class); /** * Creates a new Context Resolver. */ public ContextResolver() { } /** * Performs a lookup in Chiba's context map and returns the object denoted * by the scheme specific part of the resolver's URI. * * @return the object denoted by the scheme specific part of the * resolver's URI. * @throws XFormsException if any error occurred during link traversal. */ public Object resolve() throws XFormsException { try { String xpath = new URI(getURI()).getSchemeSpecificPart(); if (LOGGER.isDebugEnabled()) { LOGGER.debug("resolve: " + xpath); } JXPathContext contextContext = JXPathContext.newContext(getContext()); Pointer pointer = contextContext.getPointer(xpath); if (pointer.getValue() == null) { throw new JXPathException("No pointer for xpath: " + xpath); } return pointer.getNode(); } catch (Exception e) { throw new XFormsException(e); } } }