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1
45 package org.exolab.jms.config;
46
47 import java.io.IOException  ;
48 import java.io.Reader ;
49
50 import org.apache.commons.logging.Log;
51 import org.apache.commons.logging.LogFactory;
52
53 import org.exolab.castor.util.Configuration;
54 import org.exolab.castor.xml.EventProducer;
55 import org.xml.sax.AttributeList ;
56 import org.xml.sax.DocumentHandler ;
57 import org.xml.sax.ErrorHandler ;
58 import org.xml.sax.InputSource ;
59 import org.xml.sax.Locator ;
60 import org.xml.sax.Parser ;
61 import org.xml.sax.SAXException ;
62 import org.xml.sax.helpers.AttributeListImpl ;
63
64
65
80 public class AttributeExpander implements EventProducer {
81
82 private DocumentHandler _handler = null;
83 private Reader _reader = null;
84
85
88 private static final Log _log =
89 LogFactory.getLog(AttributeExpander.class);
90
91
92
97 public AttributeExpander(Reader reader) {
98 _reader = reader;
99 }
100
101
104 public void setDocumentHandler(DocumentHandler handler) {
105 _handler = handler;
106 }
107
108
111 public void start() throws SAXException {
112 Parser parser = Configuration.getDefaultParser();
113 if (parser == null) {
114 throw new SAXException ("Unable to create parser");
115 }
116
117 DocumentHandler handler = new AttributeInterceptor();
118 parser.setDocumentHandler(handler);
119 try {
120 parser.parse(new InputSource (_reader));
121 } catch (IOException exception) {
122 throw new SAXException (exception.getMessage(), exception);
123 }
124 }
125
126
130 private class AttributeInterceptor implements DocumentHandler {
131
132 public void setDocumentLocator(Locator locator) {
133 _handler.setDocumentLocator(locator);
134 }
135
136 public void startDocument() throws SAXException {
137 _handler.startDocument();
138 }
139
140 public void endDocument() throws SAXException {
141 _handler.endDocument();
142 }
143
144 public void startElement(String name, AttributeList list)
145 throws SAXException {
146
147 AttributeListImpl replaced = new AttributeListImpl ();
148 for (int i = 0; i < list.getLength(); i++) {
149 String value = expand(list.getName(i), list.getValue(i));
150 replaced.addAttribute(list.getName(i), list.getType(i), value);
151 }
152 _handler.startElement(name, replaced);
153 }
154
155 public void endElement(String name) throws SAXException {
156 _handler.endElement(name);
157 }
158
159 public void characters(char[] ch, int start, int length)
160 throws SAXException {
161 _handler.characters(ch, start, length);
162 }
163
164 public void ignorableWhitespace(char[] ch, int start, int length)
165 throws SAXException {
166 _handler.ignorableWhitespace(ch, start, length);
167 }
168
169 public void processingInstruction(String target, String data)
170 throws SAXException {
171 _handler.processingInstruction(target, data);
172 }
173
174 private String expand(String attribute, String value) {
175 StringBuffer buffer = new StringBuffer ();
176 int prev = 0;
177 int pos;
178 while ((pos = value.indexOf("${", prev)) >= 0) {
179 if (pos > 0) {
180 buffer.append(value.substring(prev, pos));
181 }
182 int index = value.indexOf('}', pos);
183 if (index < 0) {
184 _log.warn("Cannot expand " + attribute
186 + " - invalid format: " + value);
187 buffer.append("${");
188 prev = pos + 2;
189 } else {
190 String name = value.substring(pos + 2, index);
191 String property = System.getProperty(name);
192 if (property != null) {
193 buffer.append(property);
194 } else {
195 _log.warn("Cannot expand " + attribute
198 + " as property " + name
199 + " is not defined");
200 buffer.append("${");
201 buffer.append(name);
202 buffer.append("}");
203 }
204 prev = index + 1;
205 }
206 }
207 if (prev < value.length()) {
208 buffer.append(value.substring(prev));
209 }
210 String result = buffer.toString();
211 return result;
212 }
213
214 }
216 } |
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