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     */
017    package org.apache.commons.jxpath;
018    
019    import java.net.URL;
020    
021    import javax.xml.transform.Source;
022    import javax.xml.transform.Transformer;
023    import javax.xml.transform.TransformerFactory;
024    import javax.xml.transform.dom.DOMResult;
025    
026    import org.apache.commons.jxpath.xml.DocumentContainer;
027    import 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     */
044    public 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    }