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Java > Open Source Codes > org > codehaus > aspectwerkz > definition > XmlParser


1 /**************************************************************************************
2  * Copyright (c) Jonas BonŽr, Alexandre Vasseur. All rights reserved. *
3  * http://aspectwerkz.codehaus.org *
4  * ---------------------------------------------------------------------------------- *
5  * The software in this package is published under the terms of the LGPL license *
6  * a copy of which has been included with this distribution in the license.txt file. *
7  **************************************************************************************/
8 package org.codehaus.aspectwerkz.definition;
9
10 import org.codehaus.aspectwerkz.exception.DefinitionException;
11 import org.codehaus.aspectwerkz.exception.WrappedRuntimeException;
12 import org.dom4j.Document;
13 import org.dom4j.DocumentException;
14 import org.dom4j.Element;
15 import org.dom4j.DocumentHelper;
16 import org.dom4j.io.SAXReader;
17 import org.xml.sax.EntityResolver JavaDoc;
18 import org.xml.sax.InputSource JavaDoc;
19
20 import java.io.File JavaDoc;
21 import java.io.IOException JavaDoc;
22 import java.io.InputStream JavaDoc;
23 import java.io.FileInputStream JavaDoc;
24 import java.io.BufferedInputStream JavaDoc;
25 import java.net.MalformedURLException JavaDoc;
26 import java.net.URL JavaDoc;
27 import java.util.Iterator JavaDoc;
28 import java.util.List JavaDoc;
29 import java.util.Set JavaDoc;
30
31 /**
32  * Parses the XML definition file using <tt>dom4j</tt>.
33  *
34  * @author <a HREF="mailto:jboner@codehaus.org">Jonas BonŽr </a>
35  */
36 public class XmlParser {
37     /**
38      * The current DTD public id. The matching dtd will be searched as a resource.
39      */
40     private final static String JavaDoc DTD_PUBLIC_ID = "-//AspectWerkz//DTD 2.0//EN";
41
42     /**
43      * The DTD alias, for better user experience.
44      */
45     private final static String JavaDoc DTD_PUBLIC_ID_ALIAS = "-//AspectWerkz//DTD//EN";
46
47     /**
48      * A handler to the DTD stream so that we are only using one file descriptor
49      */
50     private final static InputStream JavaDoc DTD_STREAM = XmlParser.class.getResourceAsStream("/aspectwerkz2.dtd");
51
52     /**
53      * The timestamp, holding the last time that the definition was parsed.
54      */
55     private static File JavaDoc s_timestamp = new File JavaDoc(".timestamp");
56
57     /**
58      * The AspectWerkz definitions.
59      */
60     private static Set JavaDoc s_definitions = null;
61
62 // /**
63 // * Returns the aspect class names defined in the XML file.
64 // *
65 // * @param definitionFile the definition file
66 // * @return the definitions
67 // */
68 // public static List getAspectClassNames(final File definitionFile) {
69 // if (definitionFile == null) {
70 // throw new IllegalArgumentException("definition file can not be null");
71 // }
72 // if (!definitionFile.exists()) {
73 // throw new DefinitionException("definition file " + definitionFile.toString() + " does not exist");
74 // }
75 // try {
76 // return getAspectClassNames(definitionFile.toURL());
77 // } catch (MalformedURLException e) {
78 // throw new DefinitionException(definitionFile + " does not exist");
79 // }
80 // }
81
82 // /**
83 // * Returns the aspect class names defined in the XML file.
84 // *
85 // * @param definitionURL the definition URL
86 // * @return the definitions
87 // */
88 // public static List getAspectClassNames(final URL definitionURL) {
89 // if (definitionURL == null) {
90 // throw new IllegalArgumentException("definition file can not be null");
91 // }
92 // try {
93 // Document document = createDocument(definitionURL);
94 // return DocumentParser.parseAspectClassNames(document);
95 // } catch (DocumentException e) {
96 // throw new DefinitionException("XML definition file <" + definitionURL + "> has errors: " + e.toString());
97 // }
98 // }
99
100 // /**
101 // * Returns the aspect class names defined in the XML file.
102 // *
103 // * @param stream the input stream containing the document
104 // * @return the definitions
105 // */
106 // public static List getAspectClassNames(final InputStream stream) {
107 // try {
108 // Document document = createDocument(stream);
109 // return DocumentParser.parseAspectClassNames(document);
110 // } catch (DocumentException e) {
111 // throw new DefinitionException("XML definition file on classpath has errors: " + e.toString());
112 // }
113 // }
114
115 // /**
116 // * Parses the XML definition file, only if it has been updated. Uses a timestamp to check for modifications.
117 // *
118 // * @param loader the current class loader
119 // * @param definitionFile the definition file
120 // * @param isDirty flag to mark the the definition as updated or not
121 // * @return the definitions
122 // */
123 // public static Set parse(final ClassLoader loader, final File definitionFile, boolean isDirty) {
124 // if (definitionFile == null) {
125 // throw new IllegalArgumentException("definition file can not be null");
126 // }
127 // if (!definitionFile.exists()) {
128 // throw new DefinitionException("definition file " + definitionFile.toString() + " does not exist");
129 // }
130 //
131 // // if definition is not updated; don't parse but return it right away
132 // if (isNotUpdated(definitionFile)) {
133 // isDirty = false;
134 // return s_definitions;
135 // }
136 //
137 // // updated definition, ready to be parsed
138 // try {
139 // Document document = createDocument(definitionFile.toURL());
140 // s_definitions = DocumentParser.parse(loader, document);
141 // setParsingTimestamp();
142 // isDirty = true;
143 // return s_definitions;
144 // } catch (MalformedURLException e) {
145 // throw new DefinitionException(definitionFile + " does not exist");
146 // } catch (DocumentException e) {
147 // throw new DefinitionException("XML definition file <" + definitionFile + "> has errors: " + e.toString());
148 // }
149 // }
150
151 // /**
152 // * Parses the XML definition file retrieved from an input stream.
153 // *
154 // * @param loader the current class loader
155 // * @param stream the input stream containing the document
156 // * @return the definitions
157 // */
158 // public static Set parse(final ClassLoader loader, final InputStream stream) {
159 // try {
160 // Document document = createDocument(stream);
161 // s_definitions = DocumentParser.parse(loader, document);
162 // return s_definitions;
163 // } catch (DocumentException e) {
164 // throw new DefinitionException("XML definition file on classpath has errors: " + e.getMessage());
165 // }
166 // }
167
168     /**
169      * Parses the XML definition file not using the cache.
170      *
171      * @param loader the current class loader
172      * @param url the URL to the definition file
173      * @return the definition object
174      */
175     public static Set JavaDoc parseNoCache(final ClassLoader JavaDoc loader, final URL JavaDoc url) {
176         try {
177             Document document = createDocument(url);
178             s_definitions = DocumentParser.parse(loader, document);
179             return s_definitions;
180         } catch (Exception JavaDoc e) {
181             throw new WrappedRuntimeException(e);
182         }
183     }
184
185     /**
186      * Merges two DOM documents.
187      *
188      * @param document1 the first document
189      * @param document2 the second document
190      * @return the definition merged document
191      */
192     public static Document mergeDocuments(final Document document1, final Document document2) {
193         if ((document2 == null) && (document1 != null)) {
194             return document1;
195         }
196         if ((document1 == null) && (document2 != null)) {
197             return document2;
198         }
199         if ((document1 == null) && (document2 == null)) {
200             return null;
201         }
202         try {
203             Element root1 = document1.getRootElement();
204             Element root2 = document2.getRootElement();
205             for (Iterator JavaDoc it1 = root2.elementIterator(); it1.hasNext();) {
206                 Element element = (Element) it1.next();
207                 element.setParent(null);
208                 root1.add(element);
209             }
210         } catch (Exception JavaDoc e) {
211             throw new WrappedRuntimeException(e);
212         }
213         return document1;
214     }
215
216     /**
217      * Creates a DOM document.
218      *
219      * @param url the URL to the file containing the XML
220      * @return the DOM document
221      * @throws DocumentException
222      */
223     public static Document createDocument(final URL JavaDoc url) throws DocumentException {
224         SAXReader reader = new SAXReader();
225         setEntityResolver(reader);
226         InputStream JavaDoc in = null;
227         try {
228             in = url.openStream();
229             return reader.read(in);
230         } catch (IOException JavaDoc e) {
231             throw new DocumentException(e);
232         } finally {
233             try {in.close();} catch (Throwable JavaDoc t) {;}
234         }
235     }
236
237 // /**
238 // * Creates a DOM document.
239 // *
240 // * @param stream the stream containing the XML
241 // * @return the DOM document
242 // * @throws DocumentException
243 // */
244 // public static Document createDocument(final InputStream stream) throws DocumentException {
245 // SAXReader reader = new SAXReader();
246 // setEntityResolver(reader);
247 // return reader.read(stream);
248 // }
249
250     /**
251      * Creates a DOM document.
252      *
253      * @param string the string containing the XML
254      * @return the DOM document
255      * @throws DocumentException
256      */
257     public static Document createDocument(final String JavaDoc string) throws DocumentException {
258         return DocumentHelper.parseText(string);
259     }
260
261     /**
262      * Sets the entity resolver which is created based on the DTD from in the root dir of the AspectWerkz distribution.
263      *
264      * @param reader the reader to set the resolver in
265      */
266     private static void setEntityResolver(final SAXReader reader) {
267         EntityResolver JavaDoc resolver = new EntityResolver JavaDoc() {
268             public InputSource JavaDoc resolveEntity(String JavaDoc publicId, String JavaDoc systemId) {
269                 if (publicId.equals(DTD_PUBLIC_ID) || publicId.equals(DTD_PUBLIC_ID_ALIAS)) {
270                     InputStream JavaDoc in = DTD_STREAM;
271                     if (in == null) {
272                         System.err.println("AspectWerkz - WARN - could not open DTD");
273                         return new InputSource JavaDoc();
274                     } else {
275                         return new InputSource JavaDoc(in);
276                     }
277                 } else {
278                     System.err.println(
279                             "AspectWerkz - WARN - deprecated DTD "
280                             + publicId
281                             + " - consider upgrading to "
282                             + DTD_PUBLIC_ID
283                     );
284                     return new InputSource JavaDoc(); // avoid null pointer exception
285 }
286             }
287         };
288         reader.setEntityResolver(resolver);
289     }
290
291     /**
292      * Checks if the definition file has been updated since the last parsing.
293      *
294      * @param definitionFile the definition file
295      * @return boolean
296      */
297     private static boolean isNotUpdated(final File JavaDoc definitionFile) {
298         return (definitionFile.lastModified() < getParsingTimestamp()) && (s_definitions != null);
299     }
300
301     /**
302      * Sets the timestamp for the latest parsing of the definition file.
303      */
304     private static void setParsingTimestamp() {
305         final long newModifiedTime = System.currentTimeMillis();
306         s_timestamp.setLastModified(newModifiedTime);
307     }
308
309     /**
310      * Returns the timestamp for the last parsing of the definition file.
311      *
312      * @return the timestamp
313      */
314     private static long getParsingTimestamp() {
315         final long modifiedTime = s_timestamp.lastModified();
316         if (modifiedTime == 0L) {
317             // no timestamp, create a new one
318 try {
319                 s_timestamp.createNewFile();
320             } catch (IOException JavaDoc e) {
321                 throw new RuntimeException JavaDoc("could not create timestamp file: " + s_timestamp.getAbsolutePath());
322             }
323         }
324         return modifiedTime;
325     }
326 }
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