1 /*
2 * ModeShape (http://www.modeshape.org)
3 * See the COPYRIGHT.txt file distributed with this work for information
4 * regarding copyright ownership. Some portions may be licensed
5 * to Red Hat, Inc. under one or more contributor license agreements.
6 * See the AUTHORS.txt file in the distribution for a full listing of
7 * individual contributors.
8 *
9 * ModeShape is free software. Unless otherwise indicated, all code in ModeShape
10 * is licensed to you under the terms of the GNU Lesser General Public License as
11 * published by the Free Software Foundation; either version 2.1 of
12 * the License, or (at your option) any later version.
13 *
14 * ModeShape is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this software; if not, write to the Free
21 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
22 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
23 */
24 package org.modeshape.common.xml;
25
26 import java.io.IOException;
27 import java.io.OutputStream;
28 import java.util.Collection;
29 import java.util.Collections;
30 import java.util.HashMap;
31 import java.util.Map;
32 import org.modeshape.common.text.TextEncoder;
33 import org.modeshape.common.text.XmlValueEncoder;
34 import org.xml.sax.Attributes;
35 import org.xml.sax.ContentHandler;
36 import org.xml.sax.SAXException;
37 import org.xml.sax.helpers.DefaultHandler;
38
39 /**
40 * Class that adapts an arbitrary, open {@link OutputStream} to the {@link ContentHandler} interface. SAX events invoked on this
41 * object will be translated into their corresponding XML text and written to the output stream.
42 */
43 public class StreamingContentHandler extends DefaultHandler {
44
45 /** Debug setting that allows all output to be written to {@link System#out}. */
46 private static final boolean LOG_TO_CONSOLE = false;
47
48 /**
49 * Encoder to properly escape XML attribute values
50 *
51 * @see XmlValueEncoder
52 */
53 private final TextEncoder VALUE_ENCODER = new XmlValueEncoder();
54
55 /**
56 * The list of XML namespaces that are predefined and should not be exported by the content handler.
57 */
58 private final Collection<String> unexportableNamespaces;
59
60 /**
61 * The output stream to which the XML will be written
62 */
63 private final OutputStream os;
64
65 /**
66 * The XML namespace prefixes that are currently mapped
67 */
68 private final Map<String, String> mappedPrefixes;
69
70 public StreamingContentHandler( OutputStream os ) {
71 this(os, Collections.<String>emptyList());
72 }
73
74 public StreamingContentHandler( OutputStream os,
75 Collection<String> unexportableNamespaces ) {
76 this.os = os;
77 this.unexportableNamespaces = unexportableNamespaces;
78 mappedPrefixes = new HashMap<String, String>();
79 }
80
81 /**
82 * {@inheritDoc}
83 *
84 * @see org.xml.sax.helpers.DefaultHandler#characters(char[], int, int)
85 */
86 @Override
87 public void characters( char[] ch,
88 int start,
89 int length ) throws SAXException {
90 emit(VALUE_ENCODER.encode(new String(ch, start, length)));
91 }
92
93 /**
94 * {@inheritDoc}
95 *
96 * @see org.xml.sax.helpers.DefaultHandler#startDocument()
97 */
98 @Override
99 public void startDocument() throws SAXException {
100 emit("<?xml version=\"1.0\" encoding=\"UTF-8\"?>");
101 }
102
103 /**
104 * {@inheritDoc}
105 *
106 * @see org.xml.sax.helpers.DefaultHandler#startElement(java.lang.String, java.lang.String, java.lang.String,
107 * org.xml.sax.Attributes)
108 */
109 @Override
110 public void startElement( String uri,
111 String localName,
112 String name,
113 Attributes attributes ) throws SAXException {
114 emit("<");
115 emit(name);
116
117 for (Map.Entry<String, String> mapping : mappedPrefixes.entrySet()) {
118 emit(" xmlns:");
119 emit(mapping.getKey());
120 emit("=\"");
121 emit(mapping.getValue());
122 emit("\"");
123 }
124
125 mappedPrefixes.clear();
126
127 if (attributes != null) {
128 for (int i = 0; i < attributes.getLength(); i++) {
129 emit(" ");
130 emit(attributes.getQName(i));
131 emit("=\"");
132 emit(VALUE_ENCODER.encode(attributes.getValue(i)));
133 emit("\"");
134 }
135 }
136
137 emit(">");
138 }
139
140 /**
141 * {@inheritDoc}
142 *
143 * @see org.xml.sax.helpers.DefaultHandler#endElement(java.lang.String, java.lang.String, java.lang.String)
144 */
145 @Override
146 public void endElement( String uri,
147 String localName,
148 String name ) throws SAXException {
149 emit("</");
150 emit(name);
151 emit(">");
152 if (LOG_TO_CONSOLE) System.out.println();
153
154 }
155
156 /**
157 * {@inheritDoc}
158 *
159 * @see org.xml.sax.helpers.DefaultHandler#startPrefixMapping(java.lang.String, java.lang.String)
160 */
161 @Override
162 public void startPrefixMapping( String prefix,
163 String uri ) {
164 if (!unexportableNamespaces.contains(prefix)) {
165 mappedPrefixes.put(prefix, uri);
166 }
167 }
168
169 /**
170 * Writes the given text to the output stream for this {@link StreamingContentHandler}.
171 *
172 * @param text the text to output
173 * @throws SAXException if there is an error writing to the stream
174 * @see StreamingContentHandler#os
175 */
176 private void emit( String text ) throws SAXException {
177
178 try {
179 if (LOG_TO_CONSOLE) {
180 System.out.print(text);
181 }
182
183 os.write(text.getBytes());
184 } catch (IOException ioe) {
185 throw new SAXException(ioe);
186 }
187 }
188 }