Java XML Node Parent getParentNamespaces(Element el)

Description

This method traverses the DOM and grabs namespace declarations on parent elements with the intent of preserving them for children.

License

Apache License

Parameter

Parameter	Description
el	the starting element

Return

a containing prefix bindings.

Declaration

public static Map<String, String> getParentNamespaces(Element el) 

Method Source Code

//package com.java2s;
/*//from   w  w  w  . j av a  2  s  . co m
 * 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 java.util.HashMap;

import java.util.Map;

import org.w3c.dom.Attr;

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

public class Main {
    /** The namespaceURI represented by the prefix <code>xmlns</code>. */
    public static final String NS_URI_XMLNS = "http://www.w3.org/2000/xmlns/";

    /**
     * This method traverses the DOM and grabs namespace declarations
     * on parent elements with the intent of preserving them for children.  <em>Note
     * that the DOM level 3 document method {@link Element#getAttribute(java.lang.String)}
     * is not desirable in this case, as it does not respect namespace prefix
     * bindings that may affect attribute values.  (Namespaces in DOM are
     * uncategorically a mess, especially in the context of XML Schema.)</em>
     * @param el the starting element
     * @return a {@link Map} containing prefix bindings.
     */
    public static Map<String, String> getParentNamespaces(Element el) {
        HashMap<String, String> pref = new HashMap<String, String>();
        Map<String, String> mine = getMyNamespaces(el);
        Node n = el.getParentNode();
        while (n != null && n.getNodeType() != Node.DOCUMENT_NODE) {
            if (n instanceof Element) {
                Element l = (Element) n;
                NamedNodeMap nnm = l.getAttributes();
                int len = nnm.getLength();
                for (int i = 0; i < len; ++i) {
                    Attr a = (Attr) nnm.item(i);
                    if (isNSAttribute(a)) {
                        String key = getNSPrefixFromNSAttr(a);
                        String uri = a.getValue();
                        // prefer prefix bindings that are lower down in the tree.
                        if (pref.containsKey(key) || mine.containsKey(key))
                            continue;
                        pref.put(key, uri);
                    }
                }
            }
            n = n.getParentNode();
        }
        return pref;
    }

    public static Map<String, String> getMyNamespaces(Element el) {
        HashMap<String, String> mine = new HashMap<String, String>();
        NamedNodeMap nnm = el.getAttributes();
        int len = nnm.getLength();
        for (int i = 0; i < len; ++i) {
            Attr a = (Attr) nnm.item(i);
            if (isNSAttribute(a)) {
                mine.put(getNSPrefixFromNSAttr(a), a.getValue());
            }
        }
        return mine;
    }

    /**
     * Test whether an attribute contains a namespace declaration.
     * @param a an {@link Attr} to test.
     * @return <code>true</code> if the {@link Attr} is a namespace declaration
     */
    public static boolean isNSAttribute(Attr a) {
        assert a != null;
        String s = a.getNamespaceURI();
        return (s != null && s.equals(NS_URI_XMLNS));
    }

    /**
     * Fetch the non-null namespace prefix from a {@link Attr} that declares
     * a namespace.  (The DOM APIs will return <code>null</code> for a non-prefixed
     * declaration.
     * @param a the {@link Attr} with the declaration (must be non-<code>null</code).
     * @return the namespace prefix or <code>&quot;&quot;</code> if none was
     * declared, e.g., <code>xmlns=&quot;foo&quot;</code>.
     */
    public static String getNSPrefixFromNSAttr(Attr a) {
        assert a != null;
        assert isNSAttribute(a);
        if (a.getPrefix() == null) {
            return "";
        }
        return a.getName().substring(a.getPrefix().length() + 1);
    }
}

Related

1. getParentElement(Element element)
2. getParentElement(final Node node)
3. getParentElement(Node node)
4. getParentElement(Node node)
5. getParentElement(Node node)
6. getParentNode(Node node)
7. getParentNodeNoEx(Node node, String name)
8. getParentOfNode(Node node)
9. getParentOfNode(Node node)