001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements.  See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License.  You may obtain a copy of the License at
008 *
009 *     http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017package org.apache.commons.jxpath;
018
019import java.net.URL;
020
021import javax.xml.transform.Source;
022import javax.xml.transform.Transformer;
023import javax.xml.transform.TransformerFactory;
024import javax.xml.transform.dom.DOMResult;
025
026import org.apache.commons.jxpath.xml.DocumentContainer;
027import org.w3c.dom.Document;
028
029/**
030 * An XML document container reads and parses XML only when it is
031 * accessed.  JXPath traverses Containers transparently -
032 * you use the same paths to access objects in containers as you
033 * do to access those objects directly.  You can create
034 * XMLDocumentContainers for various XML documents that may or
035 * may not be accessed by XPaths.  If they are, they will be automatically
036 * read, parsed and traversed. If they are not - they won't be
037 * read at all.
038 *
039 * @deprecated 1.1 Please use {@link DocumentContainer}
040 *
041 * @author Dmitri Plotnikov
042 * @version $Revision: 652845 $ $Date: 2008-05-02 12:46:46 -0500 (Fri, 02 May 2008) $
043 */
044public class XMLDocumentContainer implements Container {
045
046    private DocumentContainer delegate;
047    private Object document;
048    private URL xmlURL;
049    private Source source;
050
051    /**
052     * Create a new XMLDocumentContainer.
053     * @param xmlURL a URL for an XML file. Use getClass().getResource(resourceName)
054     *               to load XML from a resource file.
055     */
056    public XMLDocumentContainer(URL xmlURL) {
057        this.xmlURL = xmlURL;
058        delegate = new DocumentContainer(xmlURL);
059    }
060
061    /**
062     * Create a new XMLDocumentContainer.
063     * @param source XML source
064     */
065    public XMLDocumentContainer(Source source) {
066        this.source = source;
067        if (source == null) {
068            throw new RuntimeException("Source is null");
069        }
070    }
071
072    /**
073     * Reads XML, caches it internally and returns the Document.
074     * @return Object value
075     */
076    public Object getValue() {
077        if (document == null) {
078            try {
079                if (source != null) {
080                    DOMResult result = new DOMResult();
081                    Transformer trans =
082                        TransformerFactory.newInstance().newTransformer();
083                    trans.transform(source, result);
084                    document = (Document) result.getNode();
085                }
086                else {
087                    document = delegate.getValue();
088                }
089            }
090            catch (Exception ex) {
091                throw new JXPathException(
092                    "Cannot read XML from: "
093                        + (xmlURL != null
094                            ? xmlURL.toString()
095                            : (source != null
096                                ? source.getSystemId()
097                                : "<<undefined source>>")),
098                    ex);
099            }
100        }
101        return document;
102    }
103
104    /**
105     * Throws an UnsupportedOperationException
106     * @param value to set
107     */
108    public void setValue(Object value) {
109        throw new UnsupportedOperationException();
110    }
111}