001/* DataHandler.java -- Handler for data available in multiple formats.
002   Copyright (C) 2004 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package javax.activation;
039
040import java.awt.datatransfer.DataFlavor;
041import java.awt.datatransfer.Transferable;
042import java.awt.datatransfer.UnsupportedFlavorException;
043import java.io.InputStream;
044import java.io.IOException;
045import java.io.OutputStream;
046import java.io.PipedInputStream;
047import java.io.PipedOutputStream;
048import 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 */
056public 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}