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.diff;
021
022 import java.io.IOException;
023 import java.util.Properties;
024
025 import org.apache.log4j.Logger;
026 import org.apache.wiki.WikiContext;
027 import org.apache.wiki.WikiEngine;
028 import org.apache.wiki.api.exceptions.NoRequiredPropertyException;
029 import org.apache.wiki.util.ClassUtil;
030
031
032 /**
033 * Load, initialize and delegate to the DiffProvider that will actually do the work.
034 */
035 public class DifferenceManager {
036 private static final Logger log = Logger.getLogger(DifferenceManager.class);
037
038 /**
039 * Property value for storing a diff provider. Value is {@value}.
040 */
041 public static final String PROP_DIFF_PROVIDER = "jspwiki.diffProvider";
042
043 private DiffProvider m_provider;
044
045 /**
046 * Creates a new DifferenceManager for the given engine.
047 *
048 * @param engine The WikiEngine.
049 * @param props A set of properties.
050 */
051 public DifferenceManager(WikiEngine engine, Properties props) {
052 loadProvider(props);
053
054 initializeProvider(engine, props);
055
056 log.info("Using difference provider: " + m_provider.getProviderInfo());
057 }
058
059 private void loadProvider(Properties props) {
060 String providerClassName = props.getProperty(PROP_DIFF_PROVIDER,
061 TraditionalDiffProvider.class.getName());
062
063 try {
064 Class<?> providerClass = ClassUtil.findClass("org.apache.wiki.diff", providerClassName);
065 m_provider = (DiffProvider) providerClass.newInstance();
066 } catch (ClassNotFoundException e) {
067 log.warn("Failed loading DiffProvider, will use NullDiffProvider.", e);
068 } catch (InstantiationException e) {
069 log.warn("Failed loading DiffProvider, will use NullDiffProvider.", e);
070 } catch (IllegalAccessException e) {
071 log.warn("Failed loading DiffProvider, will use NullDiffProvider.", e);
072 }
073
074 if (null == m_provider) {
075 m_provider = new DiffProvider.NullDiffProvider();
076 }
077 }
078
079
080 private void initializeProvider(WikiEngine engine, Properties props) {
081 try {
082 m_provider.initialize(engine, props);
083 } catch (NoRequiredPropertyException e1) {
084 log.warn("Failed initializing DiffProvider, will use NullDiffProvider.", e1);
085 m_provider = new DiffProvider.NullDiffProvider(); //doesn't need init'd
086 } catch (IOException e1) {
087 log.warn("Failed initializing DiffProvider, will use NullDiffProvider.", e1);
088 m_provider = new DiffProvider.NullDiffProvider(); //doesn't need init'd
089 }
090 }
091
092 /**
093 * Returns valid XHTML string to be used in any way you please.
094 *
095 * @param context The Wiki Context
096 * @param firstWikiText The old text
097 * @param secondWikiText the new text
098 * @return XHTML, or empty string, if no difference detected.
099 */
100 public String makeDiff(WikiContext context, String firstWikiText, String secondWikiText) {
101 String diff = null;
102 try {
103 diff = m_provider.makeDiffHtml(context, firstWikiText, secondWikiText);
104
105 if (diff == null) {
106 diff = "";
107 }
108 } catch (Exception e) {
109 diff = "Failed to create a diff, check the logs.";
110 log.warn(diff, e);
111 }
112 return diff;
113 }
114 }
115