JAXPPrefixResolver.java revision 9f8118474e9513f7a5b7d2a05e4a0fb15d1a6569 
1/*
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the  "License");
7 * you may not use this file except in compliance with the License.
8 * You may obtain a copy of the License at
9 *
10 *     http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18// $Id: JAXPPrefixResolver.java 468655 2006-10-28 07:12:06Z minchau $
19
20package org.apache.xpath.jaxp;
21
22import org.w3c.dom.Node;
23import org.w3c.dom.NamedNodeMap;
24import org.apache.xml.utils.PrefixResolver;
25
26import javax.xml.namespace.NamespaceContext;
27
28/**
29 * <meta name="usage" content="general"/>
30 * This class implements a Default PrefixResolver which
31 * can be used to perform prefix-to-namespace lookup
32 * for the XPath object.
33 * This class delegates the resolution to the passed NamespaceContext
34 */
35public class JAXPPrefixResolver implements PrefixResolver
36{
37
38    private NamespaceContext namespaceContext;
39
40
41    public JAXPPrefixResolver ( NamespaceContext nsContext ) {
42        this.namespaceContext = nsContext;
43    }
44
45
46    public String getNamespaceForPrefix( String prefix ) {
47        return namespaceContext.getNamespaceURI( prefix );
48    }
49
50    /**
51     * Return the base identifier.
52     *
53     * @return null
54     */
55    public String getBaseIdentifier() {
56        return null;
57    }
58
59    /**
60     * @see PrefixResolver#handlesNullPrefixes()
61     */
62    public boolean handlesNullPrefixes() {
63        return false;
64    }
65
66
67    /**
68     * The URI for the XML namespace.
69     * (Duplicate of that found in org.apache.xpath.XPathContext).
70     */
71
72    public static final String S_XMLNAMESPACEURI =
73        "http://www.w3.org/XML/1998/namespace";
74
75
76    /**
77     * Given a prefix and a Context Node, get the corresponding namespace.
78     * Warning: This will not work correctly if namespaceContext
79     * is an attribute node.
80     * @param prefix Prefix to resolve.
81     * @param namespaceContext Node from which to start searching for a
82     * xmlns attribute that binds a prefix to a namespace.
83     * @return Namespace that prefix resolves to, or null if prefix
84     * is not bound.
85     */
86    public String getNamespaceForPrefix(String prefix,
87                                      org.w3c.dom.Node namespaceContext) {
88        Node parent = namespaceContext;
89        String namespace = null;
90
91        if (prefix.equals("xml")) {
92            namespace = S_XMLNAMESPACEURI;
93        } else {
94            int type;
95
96            while ((null != parent) && (null == namespace)
97                && (((type = parent.getNodeType()) == Node.ELEMENT_NODE)
98                    || (type == Node.ENTITY_REFERENCE_NODE))) {
99
100                if (type == Node.ELEMENT_NODE) {
101                    NamedNodeMap nnm = parent.getAttributes();
102
103                    for (int i = 0; i < nnm.getLength(); i++) {
104                        Node attr = nnm.item(i);
105                        String aname = attr.getNodeName();
106                        boolean isPrefix = aname.startsWith("xmlns:");
107
108                        if (isPrefix || aname.equals("xmlns")) {
109                            int index = aname.indexOf(':');
110                            String p =isPrefix ?aname.substring(index + 1) :"";
111
112                            if (p.equals(prefix)) {
113                                namespace = attr.getNodeValue();
114                                break;
115                            }
116                        }
117                    }
118                }
119
120                parent = parent.getParentNode();
121            }
122        }
123        return namespace;
124    }
125
126}
127
128