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}