001 // This file is part of AceWiki.
002 // Copyright 2008-2012, AceWiki developers.
003 //
004 // AceWiki is free software: you can redistribute it and/or modify it under the terms of the GNU
005 // Lesser General Public License as published by the Free Software Foundation, either version 3 of
006 // the License, or (at your option) any later version.
007 //
008 // AceWiki is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
009 // even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
010 // Lesser General Public License for more details.
011 //
012 // You should have received a copy of the GNU Lesser General Public License along with AceWiki. If
013 // not, see http://www.gnu.org/licenses/.
014
015 package ch.uzh.ifi.attempto.acewiki.core;
016
017 import java.io.BufferedWriter;
018 import java.io.IOException;
019 import java.io.OutputStream;
020 import java.io.OutputStreamWriter;
021 import java.io.Writer;
022 import java.util.List;
023
024 /**
025 * This abstract class is used to export AceWiki ontologies in different formats.
026 *
027 * @author Tobias Kuhn
028 */
029 public abstract class OntologyExporter {
030
031 private Ontology ontology;
032 private OutputStream outputStream;
033 private Writer writer;
034
035 /**
036 * Creates a new exporter.
037 */
038 protected OntologyExporter() {
039 }
040
041 void init(Ontology ontology) {
042 this.ontology = ontology;
043 }
044
045 /**
046 * Writes the export content into the given output stream. The stream is closed at the end.
047 *
048 * @param outputStream The output stream.
049 */
050 public void export(OutputStream outputStream) {
051 this.outputStream = outputStream;
052 try {
053 writeContent();
054 if (writer != null) writer.close();
055 outputStream.close();
056 this.writer = null;
057 this.outputStream = null;
058 } catch (IOException ex) {
059 ex.printStackTrace();
060 }
061 }
062
063 /**
064 * Returns whether this ontology exporter is applicable in the current context.
065 *
066 * @return true if this ontology exporter is applicable.
067 */
068 public abstract boolean isApplicable();
069
070 /**
071 * Returns the name of this exporter as shown to the user.
072 *
073 * @return The name of this exporter.
074 */
075 public abstract String getName();
076
077 /**
078 * This internal method should write the export content.
079 *
080 * @throws IOException when an IO problem occurs.
081 */
082 protected abstract void writeContent() throws IOException;
083
084 /**
085 * Returns the file suffix for the given export type.
086 *
087 * @return The file suffix.
088 */
089 public abstract String getFileSuffix();
090
091 /**
092 * Returns the content type for the given export type.
093 *
094 * @return The content type.
095 */
096 public abstract String getContentType();
097
098 /**
099 * Returns the AceWiki ontology for this exporter.
100 *
101 * @return The AceWiki ontology.
102 */
103 protected Ontology getOntology() {
104 return ontology;
105 }
106
107 /**
108 * Returns the list of all ontology elements.
109 *
110 * @return The ontology elements.
111 */
112 protected List<OntologyElement> getOntologyElements() {
113 return ontology.getOntologyElements();
114 }
115
116 /**
117 * Returns the current output stream.
118 *
119 * @return The current output stream.
120 */
121 protected OutputStream getOutputStream() {
122 return outputStream;
123 }
124
125 /**
126 * Writes the given string into the current output stream.
127 *
128 * @param str The string to be written.
129 * @throws IOException when an IO problem occurs.
130 */
131 protected void write(String str) throws IOException {
132 if (writer == null) {
133 writer = new BufferedWriter(new OutputStreamWriter(outputStream));
134 }
135 writer.write(str);
136 }
137
138 }