/* * reserved comment block * DO NOT REMOVE OR ALTER! */ /* * Copyright 1999-2004 The Apache Software Foundation. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * $Id: XPathAPI.java,v 1.2.4.1 2005/09/10 18:18:23 jeffsuttor Exp $ */ package com.sun.org.apache.xpath.internal; import javax.xml.transform.TransformerException; import com.sun.org.apache.xml.internal.utils.PrefixResolver; import com.sun.org.apache.xml.internal.utils.PrefixResolverDefault; import com.sun.org.apache.xpath.internal.objects.XObject; import org.w3c.dom.Document; import org.w3c.dom.Node; import org.w3c.dom.NodeList; import org.w3c.dom.traversal.NodeIterator; /** * The methods in this class are convenience methods into the * low-level XPath API. * These functions tend to be a little slow, since a number of objects must be * created for each evaluation. A faster way is to precompile the * XPaths using the low-level API, and then just use the XPaths * over and over. * * NOTE: In particular, each call to this method will create a new * XPathContext, a new DTMManager... and thus a new DTM. That's very * safe, since it guarantees that you're always processing against a * fully up-to-date view of your document. But it's also portentially * very expensive, since you're rebuilding the DTM every time. You should * consider using an instance of CachedXPathAPI rather than these static * methods. * * @see XPath Specification * */ public class XPathAPI { /** * Use an XPath string to select a single node. XPath namespace * prefixes are resolved from the context node, which may not * be what you want (see the next method). * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @return The first node found that matches the XPath, or null. * * @throws TransformerException */ public static Node selectSingleNode(Node contextNode, String str) throws TransformerException { return selectSingleNode(contextNode, str, contextNode); } /** * Use an XPath string to select a single node. * XPath namespace prefixes are resolved from the namespaceNode. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces. * @return The first node found that matches the XPath, or null. * * @throws TransformerException */ public static Node selectSingleNode( Node contextNode, String str, Node namespaceNode) throws TransformerException { // Have the XObject return its result as a NodeSetDTM. NodeIterator nl = selectNodeIterator(contextNode, str, namespaceNode); // Return the first node, or null return nl.nextNode(); } /** * Use an XPath string to select a nodelist. * XPath namespace prefixes are resolved from the contextNode. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @return A NodeIterator, should never be null. * * @throws TransformerException */ public static NodeIterator selectNodeIterator(Node contextNode, String str) throws TransformerException { return selectNodeIterator(contextNode, str, contextNode); } /** * Use an XPath string to select a nodelist. * XPath namespace prefixes are resolved from the namespaceNode. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces. * @return A NodeIterator, should never be null. * * @throws TransformerException */ public static NodeIterator selectNodeIterator( Node contextNode, String str, Node namespaceNode) throws TransformerException { // Execute the XPath, and have it return the result XObject list = eval(contextNode, str, namespaceNode); // Have the XObject return its result as a NodeSetDTM. return list.nodeset(); } /** * Use an XPath string to select a nodelist. * XPath namespace prefixes are resolved from the contextNode. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @return A NodeIterator, should never be null. * * @throws TransformerException */ public static NodeList selectNodeList(Node contextNode, String str) throws TransformerException { return selectNodeList(contextNode, str, contextNode); } /** * Use an XPath string to select a nodelist. * XPath namespace prefixes are resolved from the namespaceNode. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces. * @return A NodeIterator, should never be null. * * @throws TransformerException */ public static NodeList selectNodeList( Node contextNode, String str, Node namespaceNode) throws TransformerException { // Execute the XPath, and have it return the result XObject list = eval(contextNode, str, namespaceNode); // Return a NodeList. return list.nodelist(); } /** * Evaluate XPath string to an XObject. Using this method, * XPath namespace prefixes will be resolved from the namespaceNode. * @param contextNode The node to start searching from. * @param str A valid XPath string. * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null. * @see com.sun.org.apache.xpath.internal.objects.XObject * @see com.sun.org.apache.xpath.internal.objects.XNull * @see com.sun.org.apache.xpath.internal.objects.XBoolean * @see com.sun.org.apache.xpath.internal.objects.XNumber * @see com.sun.org.apache.xpath.internal.objects.XString * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag * * @throws TransformerException */ public static XObject eval(Node contextNode, String str) throws TransformerException { return eval(contextNode, str, contextNode); } /** * Evaluate XPath string to an XObject. * XPath namespace prefixes are resolved from the namespaceNode. * The implementation of this is a little slow, since it creates * a number of objects each time it is called. This could be optimized * to keep the same objects around, but then thread-safety issues would arise. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @param namespaceNode The node from which prefixes in the XPath will be resolved to namespaces. * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null. * @see com.sun.org.apache.xpath.internal.objects.XObject * @see com.sun.org.apache.xpath.internal.objects.XNull * @see com.sun.org.apache.xpath.internal.objects.XBoolean * @see com.sun.org.apache.xpath.internal.objects.XNumber * @see com.sun.org.apache.xpath.internal.objects.XString * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag * * @throws TransformerException */ public static XObject eval(Node contextNode, String str, Node namespaceNode) throws TransformerException { // Since we don't have a XML Parser involved here, install some default support // for things like namespaces, etc. // (Changed from: XPathContext xpathSupport = new XPathContext(); // because XPathContext is weak in a number of areas... perhaps // XPathContext should be done away with.) XPathContext xpathSupport = new XPathContext(); // Create an object to resolve namespace prefixes. // XPath namespaces are resolved from the input context node's document element // if it is a root node, or else the current context node (for lack of a better // resolution space, given the simplicity of this sample code). PrefixResolverDefault prefixResolver = new PrefixResolverDefault( (namespaceNode.getNodeType() == Node.DOCUMENT_NODE) ? ((Document) namespaceNode).getDocumentElement() : namespaceNode); // Create the XPath object. XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null); // Execute the XPath, and have it return the result // return xpath.execute(xpathSupport, contextNode, prefixResolver); int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode); return xpath.execute(xpathSupport, ctxtNode, prefixResolver); } /** * Evaluate XPath string to an XObject. * XPath namespace prefixes are resolved from the namespaceNode. * The implementation of this is a little slow, since it creates * a number of objects each time it is called. This could be optimized * to keep the same objects around, but then thread-safety issues would arise. * * @param contextNode The node to start searching from. * @param str A valid XPath string. * @param prefixResolver Will be called if the parser encounters namespace * prefixes, to resolve the prefixes to URLs. * @return An XObject, which can be used to obtain a string, number, nodelist, etc, should never be null. * @see com.sun.org.apache.xpath.internal.objects.XObject * @see com.sun.org.apache.xpath.internal.objects.XNull * @see com.sun.org.apache.xpath.internal.objects.XBoolean * @see com.sun.org.apache.xpath.internal.objects.XNumber * @see com.sun.org.apache.xpath.internal.objects.XString * @see com.sun.org.apache.xpath.internal.objects.XRTreeFrag * * @throws TransformerException */ public static XObject eval( Node contextNode, String str, PrefixResolver prefixResolver) throws TransformerException { // Since we don't have a XML Parser involved here, install some default support // for things like namespaces, etc. // (Changed from: XPathContext xpathSupport = new XPathContext(); // because XPathContext is weak in a number of areas... perhaps // XPathContext should be done away with.) // Create the XPath object. XPath xpath = new XPath(str, null, prefixResolver, XPath.SELECT, null); // Execute the XPath, and have it return the result XPathContext xpathSupport = new XPathContext(); int ctxtNode = xpathSupport.getDTMHandleFromNode(contextNode); return xpath.execute(xpathSupport, ctxtNode, prefixResolver); } }