001 /* DataHandler.java -- Handler for data available in multiple formats.
002 Copyright (C) 2004 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package javax.activation;
039
040 import java.awt.datatransfer.DataFlavor;
041 import java.awt.datatransfer.Transferable;
042 import java.awt.datatransfer.UnsupportedFlavorException;
043 import java.io.InputStream;
044 import java.io.IOException;
045 import java.io.OutputStream;
046 import java.io.PipedInputStream;
047 import java.io.PipedOutputStream;
048 import java.net.URL;
049
050 /**
051 * Handler for data available in multiple sources and formats.
052 *
053 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
054 * @version 1.1
055 */
056 public class DataHandler
057 implements Transferable
058 {
059
060 private static final DataFlavor[] NO_FLAVORS = new DataFlavor[0];
061 private static DataContentHandlerFactory factory = null;
062
063 private final DataSource dataSource;
064 private DataSource objDataSource;
065 private Object object;
066 private String objectMimeType;
067 private CommandMap currentCommandMap;
068 private DataFlavor[] transferFlavors = NO_FLAVORS;
069 private DataContentHandler dataContentHandler;
070 private DataContentHandler factoryDCH;
071 private DataContentHandlerFactory oldFactory;
072 private String shortType;
073
074 /**
075 * Constructor in which the data is read from a data source.
076 * @param ds the data source
077 */
078 public DataHandler(DataSource ds)
079 {
080 dataSource = ds;
081 oldFactory = factory;
082 }
083
084 /**
085 * Constructor using a reified object representation.
086 * @param obj the object representation of the data
087 * @param mimeType the MIME type of the object
088 */
089 public DataHandler(Object obj, String mimeType)
090 {
091 dataSource = null;
092 object = obj;
093 objectMimeType = mimeType;
094 oldFactory = factory;
095 }
096
097 /**
098 * Constructor in which the data is read from a URL.
099 * @param url the URL
100 */
101 public DataHandler(URL url)
102 {
103 dataSource = new URLDataSource(url);
104 oldFactory = factory;
105 }
106
107 /**
108 * Returns the data source from which data is read.
109 */
110 public DataSource getDataSource()
111 {
112 if (dataSource != null)
113 {
114 return dataSource;
115 }
116 if (objDataSource == null)
117 {
118 objDataSource = new DataHandlerDataSource(this);
119 }
120 return objDataSource;
121 }
122
123 /**
124 * Returns the name of the data object if created with a DataSource.
125 */
126 public String getName()
127 {
128 if (dataSource != null)
129 {
130 return dataSource.getName();
131 }
132 return null;
133 }
134
135 /**
136 * Returns the MIME type of the data (with parameters).
137 */
138 public String getContentType()
139 {
140 if (dataSource != null)
141 {
142 return dataSource.getContentType();
143 }
144 return objectMimeType;
145 }
146
147 /**
148 * Returns an input stream from which the data can be read.
149 */
150 public InputStream getInputStream()
151 throws IOException
152 {
153 if (dataSource != null)
154 {
155 return dataSource.getInputStream();
156 }
157 DataContentHandler dch = getDataContentHandler();
158 if (dch == null)
159 {
160 throw new UnsupportedDataTypeException("no DCH for MIME type " +
161 getShortType());
162 }
163 if ((dch instanceof ObjectDataContentHandler) &&
164 ((ObjectDataContentHandler)dch).getDCH() == null)
165 {
166 throw new UnsupportedDataTypeException("no object DCH " +
167 "for MIME type " +
168 getShortType());
169 }
170 PipedOutputStream pos = new PipedOutputStream();
171 DataContentHandlerWriter dchw =
172 new DataContentHandlerWriter(dch, object, objectMimeType, pos);
173 Thread thread = new Thread(dchw, "DataHandler.getInputStream");
174 thread.start();
175 return new PipedInputStream(pos);
176 }
177
178 static class DataContentHandlerWriter
179 implements Runnable
180 {
181
182 DataContentHandler dch;
183 Object object;
184 String mimeType;
185 OutputStream out;
186
187 DataContentHandlerWriter(DataContentHandler dch, Object object,
188 String mimeType, OutputStream out)
189 {
190 this.dch = dch;
191 this.object = object;
192 this.mimeType = mimeType;
193 this.out = out;
194 }
195
196 public void run()
197 {
198 try
199 {
200 dch.writeTo(object, mimeType, out);
201 }
202 catch(IOException e)
203 {
204 }
205 finally
206 {
207 try
208 {
209 out.close();
210 }
211 catch(IOException e)
212 {
213 }
214 }
215 }
216 }
217
218 /**
219 * Writes the data as a byte stream.
220 * @param os the stream to write to
221 */
222 public void writeTo(OutputStream os)
223 throws IOException
224 {
225 if (dataSource != null)
226 {
227 InputStream in = dataSource.getInputStream();
228 byte[] buf = new byte[8192];
229 for (int len = in.read(buf); len != -1; len = in.read(buf))
230 {
231 os.write(buf, 0, len);
232 }
233 in.close();
234 }
235 else
236 {
237 DataContentHandler dch = getDataContentHandler();
238 dch.writeTo(object, objectMimeType, os);
239 }
240 }
241
242 /**
243 * Returns an output stream that can be used to overwrite the underlying
244 * data, if the DataSource constructor was used.
245 */
246 public OutputStream getOutputStream()
247 throws IOException
248 {
249 if (dataSource != null)
250 {
251 return dataSource.getOutputStream();
252 }
253 return null;
254 }
255
256 /**
257 * Returns the data flavors in which this data is available.
258 */
259 public synchronized DataFlavor[] getTransferDataFlavors()
260 {
261 if (factory != oldFactory || transferFlavors == NO_FLAVORS)
262 {
263 DataContentHandler dch = getDataContentHandler();
264 transferFlavors = dch.getTransferDataFlavors();
265 }
266 return transferFlavors;
267 }
268
269 /**
270 * Indicates whether the specified data flavor is supported for this
271 * data.
272 */
273 public boolean isDataFlavorSupported(DataFlavor flavor)
274 {
275 DataFlavor[] flavors = getTransferDataFlavors();
276 for (int i = 0; i < flavors.length; i++)
277 {
278 if (flavors[i].equals(flavor))
279 {
280 return true;
281 }
282 }
283 return false;
284 }
285
286 /**
287 * Returns an object representing the data to be transferred.
288 * @param flavor the requested data flavor
289 */
290 public Object getTransferData(DataFlavor flavor)
291 throws UnsupportedFlavorException, IOException
292 {
293 DataContentHandler dch = getDataContentHandler();
294 return dch.getTransferData(flavor, dataSource);
295 }
296
297 /**
298 * Sets the command map to be used by this data handler.
299 * Setting to null uses the default command map.
300 * @param commandMap the command map to use
301 */
302 public synchronized void setCommandMap(CommandMap commandMap)
303 {
304 if (commandMap != currentCommandMap || commandMap == null)
305 {
306 transferFlavors = NO_FLAVORS;
307 dataContentHandler = null;
308 currentCommandMap = commandMap;
309 }
310 }
311
312 /**
313 * Returns the preferred commands for this type of data.
314 */
315 public CommandInfo[] getPreferredCommands()
316 {
317 CommandMap commandMap = getCommandMap();
318 return commandMap.getPreferredCommands(getShortType());
319 }
320
321 /**
322 * Returns the complete list of commands for this type of data.
323 */
324 public CommandInfo[] getAllCommands()
325 {
326 CommandMap commandMap = getCommandMap();
327 return commandMap.getAllCommands(getShortType());
328 }
329
330 /**
331 * Returns the specified command.
332 * @param cmdName the command name
333 */
334 public CommandInfo getCommand(String cmdName)
335 {
336 CommandMap commandMap = getCommandMap();
337 return commandMap.getCommand(getShortType(), cmdName);
338 }
339
340 /**
341 * Returns the data as a reified object.
342 */
343 public Object getContent()
344 throws IOException
345 {
346 DataContentHandler dch = getDataContentHandler();
347 return dch.getContent(getDataSource());
348 }
349
350 /**
351 * Returns the instantiated bean using the specified command.
352 * @param cmdInfo the command to instantiate the bean with
353 */
354 public Object getBean(CommandInfo cmdInfo)
355 {
356 try
357 {
358 return cmdInfo.getCommandObject(this, getClass().getClassLoader());
359 }
360 catch (IOException e)
361 {
362 e.printStackTrace(System.err);
363 return null;
364 }
365 catch (ClassNotFoundException e)
366 {
367 e.printStackTrace(System.err);
368 return null;
369 }
370 }
371
372 /**
373 * Sets the data content handler factory.
374 * If the factory has already been set, throws an Error.
375 * @param newFactory the factory to set
376 */
377 public static synchronized void
378 setDataContentHandlerFactory(DataContentHandlerFactory newFactory)
379 {
380 if (factory != null)
381 {
382 throw new Error("DataContentHandlerFactory already defined");
383 }
384 SecurityManager security = System.getSecurityManager();
385 if (security != null)
386 {
387 try
388 {
389 security.checkSetFactory();
390 }
391 catch (SecurityException e)
392 {
393 if (newFactory != null && DataHandler.class.getClassLoader()
394 != newFactory.getClass().getClassLoader())
395 {
396 throw e;
397 }
398 }
399 }
400 factory = newFactory;
401 }
402
403 /*
404 * Returns just the base part of the data's content-type, with no
405 * parameters.
406 */
407 private synchronized String getShortType()
408 {
409 if (shortType == null)
410 {
411 String contentType = getContentType();
412 try
413 {
414 MimeType mimeType = new MimeType(contentType);
415 shortType = mimeType.getBaseType();
416 }
417 catch (MimeTypeParseException e)
418 {
419 shortType = contentType;
420 }
421 }
422 return shortType;
423 }
424
425 /*
426 * Returns the command map for this handler.
427 */
428 private synchronized CommandMap getCommandMap()
429 {
430 if (currentCommandMap != null)
431 {
432 return currentCommandMap;
433 }
434 return CommandMap.getDefaultCommandMap();
435 }
436
437 /*
438 * Returns the DCH for this handler.
439 */
440 private synchronized DataContentHandler getDataContentHandler()
441 {
442 if (factory != oldFactory)
443 {
444 oldFactory = factory;
445 factoryDCH = null;
446 dataContentHandler = null;
447 transferFlavors = NO_FLAVORS;
448 }
449 if (dataContentHandler != null)
450 {
451 return dataContentHandler;
452 }
453 String mimeType = getShortType();
454 if (factoryDCH == null && factory != null)
455 {
456 factoryDCH = factory.createDataContentHandler(mimeType);
457 }
458 if (factoryDCH != null)
459 {
460 dataContentHandler = factoryDCH;
461 }
462 if (dataContentHandler == null)
463 {
464 CommandMap commandMap = getCommandMap();
465 dataContentHandler = commandMap.createDataContentHandler(mimeType);
466 }
467 if (dataSource != null)
468 {
469 dataContentHandler =
470 new DataSourceDataContentHandler(dataContentHandler, dataSource);
471 }
472 else
473 {
474 dataContentHandler =
475 new ObjectDataContentHandler(dataContentHandler, object,
476 objectMimeType);
477 }
478 return dataContentHandler;
479 }
480
481 }