001 /*
002 Licensed to the Apache Software Foundation (ASF) under one
003 or more contributor license agreements. See the NOTICE file
004 distributed with this work for additional information
005 regarding copyright ownership. The ASF licenses this file
006 to you under the Apache License, Version 2.0 (the
007 "License"); you may not use this file except in compliance
008 with the License. You may obtain a copy of the License at
009
010 http://www.apache.org/licenses/LICENSE-2.0
011
012 Unless required by applicable law or agreed to in writing,
013 software distributed under the License is distributed on an
014 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 KIND, either express or implied. See the License for the
016 specific language governing permissions and limitations
017 under the License.
018 */
019
020 package org.apache.wiki.util;
021
022 import org.apache.commons.lang.StringUtils;
023 import org.apache.log4j.Logger;
024 import org.jdom2.Document;
025 import org.jdom2.Element;
026 import org.jdom2.JDOMException;
027 import org.jdom2.filter.Filters;
028 import org.jdom2.input.SAXBuilder;
029 import org.jdom2.xpath.XPathExpression;
030 import org.jdom2.xpath.XPathFactory;
031
032 import java.io.IOException;
033 import java.io.InputStream;
034 import java.net.URL;
035 import java.util.ArrayList;
036 import java.util.Collections;
037 import java.util.Enumeration;
038 import java.util.HashSet;
039 import java.util.List;
040 import java.util.Set;
041
042 /**
043 * Utility class to parse XML files.
044 * <p>
045 * This uses JDOM2 as its backing implementation.
046 * </p>
047 *
048 * @since 2.10
049 */
050 public final class XmlUtil
051 {
052 private static final Logger log = Logger.getLogger( XmlUtil.class );
053
054 private XmlUtil() {}
055
056 /**
057 * Parses the given XML file and returns the requested nodes. If there's an error accessing or parsing the file, an
058 * empty list is returned.
059 *
060 * @param xml file to parse; matches all resources from classpath, filters repeated items.
061 * @param requestedNodes requestd nodes on the xml file
062 * @return the requested nodes of the XML file.
063 */
064 public static List<Element> parse( String xml, String requestedNodes )
065 {
066 if( StringUtils.isNotEmpty( xml ) && StringUtils.isNotEmpty( requestedNodes ) ) {
067 Set<Element> readed = new HashSet<Element>();
068 SAXBuilder builder = new SAXBuilder();
069 try {
070 Enumeration< URL > resources = XmlUtil.class.getClassLoader().getResources( xml );
071 while( resources.hasMoreElements() ) {
072 URL resource = resources.nextElement();
073 log.debug( "reading " + resource.toString() );
074 Document doc = builder.build( resource );
075 XPathFactory xpfac = XPathFactory.instance();
076 XPathExpression<Element> xp = xpfac.compile( requestedNodes, Filters.element() );
077 readed.addAll( xp.evaluate( doc ) ); // filter out repeated items
078 }
079 return new ArrayList<Element>( readed );
080 } catch ( IOException ioe ) {
081 log.error( "Couldn't load all " + xml + " resources", ioe );
082 } catch ( JDOMException jdome ) {
083 log.error( "error parsing " + xml + " resources", jdome );
084 }
085 }
086 return Collections.<Element>emptyList();
087 }
088
089
090 /**
091 * Parses the given stream and returns the requested nodes. If there's an error accessing or parsing the stream, an
092 * empty list is returned.
093 *
094 * @param xmlStream stream to parse.
095 * @param requestedNodes requestd nodes on the xml stream.
096 * @return the requested nodes of the XML stream.
097 */
098 public static List<Element> parse( InputStream xmlStream, String requestedNodes )
099 {
100 if( xmlStream != null && StringUtils.isNotEmpty( requestedNodes ) ) {
101 SAXBuilder builder = new SAXBuilder();
102 try {
103 Document doc = builder.build(xmlStream);
104 XPathFactory xpfac = XPathFactory.instance();
105 XPathExpression< Element > xp = xpfac.compile(requestedNodes,Filters.element());
106 return xp.evaluate( doc );
107 } catch ( IOException ioe ) {
108 log.error( "Couldn't load all " + xmlStream + " resources", ioe );
109 } catch ( JDOMException jdome ) {
110 log.error( "error parsing " + xmlStream + " resources", jdome );
111 }
112 }
113 return Collections.<Element>emptyList();
114 }
115
116 }