Java tutorial
/* * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and contributors. * * 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. * * Contributors: * Nuxeo - initial API and implementation * * $Id$ */ package org.nuxeo.common.xmap; import java.io.IOException; import java.io.StringReader; import java.util.Collection; import java.util.Map; import javax.xml.parsers.DocumentBuilderFactory; import javax.xml.parsers.ParserConfigurationException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.w3c.dom.Document; import org.w3c.dom.DocumentFragment; import org.w3c.dom.Element; import org.w3c.dom.Node; import org.xml.sax.InputSource; import org.xml.sax.SAXException; /** * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a> */ public final class DOMHelper { private static final Log log = LogFactory.getLog(DOMHelper.class); // Utility class. private DOMHelper() { } /** * Gets the value of the node at the given path relative to the given base * element. * <p> * For element nodes the value is the text content and for the attributes * node the attribute value. * * @return the node value or null if no such node was found */ public static String getNodeValue(Element base, Path path) { Node node = getElementNode(base, path); if (node != null) { if (path.attribute != null) { Node at = node.getAttributes().getNamedItem(path.attribute); return at != null ? at.getNodeValue() : null; } else { return node.getTextContent(); } } return null; } /** * Visits the nodes selected by the given path using the given visitor. */ public static void visitNodes(Context ctx, XAnnotatedList xam, Element base, Path path, NodeVisitor visitor, Collection<Object> result) { Node el = base; int len = path.segments.length - 1; for (int i = 0; i < len; i++) { el = getElementNode(el, path.segments[i]); if (el == null) { return; } } String name = path.segments[len]; if (path.attribute != null) { visitAttributes(ctx, xam, el, name, path.attribute, visitor, result); } else { visitElements(ctx, xam, el, name, visitor, result); } } public static void visitAttributes(Context ctx, XAnnotatedList xam, Node base, String name, String attrName, NodeVisitor visitor, Collection<Object> result) { Node p = base.getFirstChild(); while (p != null) { if (p.getNodeType() == Node.ELEMENT_NODE) { if (name.equals(p.getNodeName())) { Node at = p.getAttributes().getNamedItem(attrName); if (at != null) { visitor.visitNode(ctx, xam, at, result); } } } p = p.getNextSibling(); } } public static void visitElements(Context ctx, XAnnotatedList xam, Node base, String name, NodeVisitor visitor, Collection<Object> result) { Node p = base.getFirstChild(); while (p != null) { if (p.getNodeType() == Node.ELEMENT_NODE) { if (name.equals(p.getNodeName())) { visitor.visitNode(ctx, xam, p, result); } } p = p.getNextSibling(); } } public static void visitMapNodes(Context ctx, XAnnotatedMap xam, Element base, Path path, NodeMapVisitor visitor, Map<String, Object> result) { Node el = base; int len = path.segments.length - 1; for (int i = 0; i < len; i++) { el = getElementNode(el, path.segments[i]); if (el == null) { return; } } String name = path.segments[len]; if (path.attribute != null) { visitMapAttributes(ctx, xam, el, name, path.attribute, visitor, result); } else { visitMapElements(ctx, xam, el, name, visitor, result); } } public static void visitMapAttributes(Context ctx, XAnnotatedMap xam, Node base, String name, String attrName, NodeMapVisitor visitor, Map<String, Object> result) { Node p = base.getFirstChild(); while (p != null) { if (p.getNodeType() == Node.ELEMENT_NODE) { if (name.equals(p.getNodeName())) { Node at = p.getAttributes().getNamedItem(attrName); if (at != null) { String key = getNodeValue((Element) p, xam.key); if (key != null) { visitor.visitNode(ctx, xam, at, key, result); } } } } p = p.getNextSibling(); } } public static void visitMapElements(Context ctx, XAnnotatedMap xam, Node base, String name, NodeMapVisitor visitor, Map<String, Object> result) { Node p = base.getFirstChild(); while (p != null) { if (p.getNodeType() == Node.ELEMENT_NODE) { if (name.equals(p.getNodeName())) { String key = getNodeValue((Element) p, xam.key); if (key != null) { visitor.visitNode(ctx, xam, p, key, result); } } } p = p.getNextSibling(); } } /** * Gets the first child element node having the given name. */ public static Node getElementNode(Node base, String name) { Node node = base.getFirstChild(); while (node != null) { if (node.getNodeType() == Node.ELEMENT_NODE) { if (name.equals(node.getNodeName())) { return node; } } node = node.getNextSibling(); } return null; } public static Node getElementNode(Node base, Path path) { Node el = base; int len = path.segments.length; for (int i = 0; i < len; i++) { el = getElementNode(el, path.segments[i]); if (el == null) { return null; } } return el; } public interface NodeVisitor { void visitNode(Context ctx, XAnnotatedMember xam, Node node, Collection<Object> result); } public interface NodeMapVisitor { void visitNode(Context ctx, XAnnotatedMember xam, Node node, String key, Map<String, Object> result); } /** * Parses a string containing XML and returns a DocumentFragment containing * the nodes of the parsed XML. */ public static void loadFragment(Element el, String fragment) { // Wrap the fragment in an arbitrary element fragment = "<fragment>" + fragment + "</fragment>"; try { // Create a DOM builder and parse the fragment DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance(); Document d = factory.newDocumentBuilder().parse(new InputSource(new StringReader(fragment))); Document doc = el.getOwnerDocument(); // Import the nodes of the new document into doc so that they // will be compatible with doc Node node = doc.importNode(d.getDocumentElement(), true); // Create the document fragment node to hold the new nodes DocumentFragment docfrag = doc.createDocumentFragment(); // Move the nodes into the fragment while (node.hasChildNodes()) { el.appendChild(node.removeChild(node.getFirstChild())); } } catch (ParserConfigurationException e) { log.error(e, e); } catch (SAXException e) { log.error(e, e); } catch (IOException e) { log.error(e, e); } } }