Utils.java Source code

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.
 */

import javax.xml.XMLConstants;

import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;

/**
 * Few simple utils to read DOM. This is originally from the Jakarta Commons Modeler.
 * 
 * @author Costin Manolache
 */
public class Utils {
    private static final String XMLNAMESPACE = "xmlns";

    /**
     * Set a namespace/prefix on an element if it is not set already. First off, it searches for the element
     * for the prefix associated with the specified namespace. If the prefix isn't null, then this is
     * returned. Otherwise, it creates a new attribute using the namespace/prefix passed as parameters.
     * 
     * @param element
     * @param namespace
     * @param prefix
     * @return the prefix associated with the set namespace
     */
    public static String setNamespace(Element element, String namespace, String prefix) {
        String pre = getPrefixRecursive(element, namespace);
        if (pre != null) {
            return pre;
        }
        element.setAttributeNS(XMLConstants.XMLNS_ATTRIBUTE_NS_URI, "xmlns:" + prefix, namespace);
        return prefix;
    }

    public static String getPrefixRecursive(Element el, String ns) {
        String prefix = getPrefix(el, ns);
        if (prefix == null && el.getParentNode() instanceof Element) {
            prefix = getPrefixRecursive((Element) el.getParentNode(), ns);
        }
        return prefix;
    }

    public static String getPrefix(Element el, String ns) {
        NamedNodeMap atts = el.getAttributes();
        for (int i = 0; i < atts.getLength(); i++) {
            Node node = atts.item(i);
            String name = node.getNodeName();
            if (ns.equals(node.getNodeValue())
                    && (name != null && (XMLNAMESPACE.equals(name) || name.startsWith(XMLNAMESPACE + ":")))) {
                return node.getPrefix();
            }
        }
        return null;
    }
}