1 /* 2 * Copyright (c) 1996, 2014, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package java.awt.datatransfer; 27 28 import java.awt.EventQueue; 29 30 import java.util.Objects; 31 import java.util.Set; 32 import java.util.HashSet; 33 import java.util.Arrays; 34 35 import java.io.IOException; 36 37 /** 38 * A class that implements a mechanism to transfer data using 39 * cut/copy/paste operations. 40 * <p> 41 * {@link FlavorListener}s may be registered on an instance of the 42 * Clipboard class to be notified about changes to the set of 43 * {@link DataFlavor}s available on this clipboard (see 44 * {@link #addFlavorListener}). 45 * 46 * @see java.awt.Toolkit#getSystemClipboard 47 * @see java.awt.Toolkit#getSystemSelection 48 * 49 * @author Amy Fowler 50 * @author Alexander Gerasimov 51 */ 52 public class Clipboard { 53 54 String name; 55 56 /** 57 * The owner of the clipboard. 58 */ 59 protected ClipboardOwner owner; 60 /** 61 * Contents of the clipboard. 62 */ 63 protected Transferable contents; 64 65 /** 66 * An aggregate of flavor listeners registered on this local clipboard. 67 * 68 * @since 1.5 69 */ 70 private final Set<FlavorListener> flavorListeners = new HashSet<>(); 71 72 /** 73 * A set of <code>DataFlavor</code>s that is available on 74 * this local clipboard. It is used for tracking changes 75 * of <code>DataFlavor</code>s available on this clipboard. 76 * 77 * @since 1.5 78 */ 79 private Set<DataFlavor> currentDataFlavors; 80 81 /** 82 * Creates a clipboard object. 83 * @param name for the clipboard 84 * @see java.awt.Toolkit#getSystemClipboard 85 */ 86 public Clipboard(String name) { 87 this.name = name; 88 } 89 90 /** 91 * Returns the name of this clipboard object. 92 * @return the name of this clipboard object 93 * 94 * @see java.awt.Toolkit#getSystemClipboard 95 */ 96 public String getName() { 97 return name; 98 } 99 100 /** 101 * Sets the current contents of the clipboard to the specified 102 * transferable object and registers the specified clipboard owner 103 * as the owner of the new contents. 104 * <p> 105 * If there is an existing owner different from the argument 106 * <code>owner</code>, that owner is notified that it no longer 107 * holds ownership of the clipboard contents via an invocation 108 * of <code>ClipboardOwner.lostOwnership()</code> on that owner. 109 * An implementation of <code>setContents()</code> is free not 110 * to invoke <code>lostOwnership()</code> directly from this method. 111 * For example, <code>lostOwnership()</code> may be invoked later on 112 * a different thread. The same applies to <code>FlavorListener</code>s 113 * registered on this clipboard. 114 * <p> 115 * The method throws <code>IllegalStateException</code> if the clipboard 116 * is currently unavailable. For example, on some platforms, the system 117 * clipboard is unavailable while it is accessed by another application. 118 * 119 * @param contents the transferable object representing the 120 * clipboard content 121 * @param owner the object which owns the clipboard content 122 * @throws IllegalStateException if the clipboard is currently unavailable 123 * @see java.awt.Toolkit#getSystemClipboard 124 */ 125 public synchronized void setContents(Transferable contents, ClipboardOwner owner) { 126 final ClipboardOwner oldOwner = this.owner; 127 final Transferable oldContents = this.contents; 128 129 this.owner = owner; 130 this.contents = contents; 131 132 if (oldOwner != null && oldOwner != owner) { 133 EventQueue.invokeLater(() -> oldOwner.lostOwnership(Clipboard.this, oldContents)); 134 } 135 fireFlavorsChanged(); 136 } 137 138 /** 139 * Returns a transferable object representing the current contents 140 * of the clipboard. If the clipboard currently has no contents, 141 * it returns <code>null</code>. The parameter Object requestor is 142 * not currently used. The method throws 143 * <code>IllegalStateException</code> if the clipboard is currently 144 * unavailable. For example, on some platforms, the system clipboard is 145 * unavailable while it is accessed by another application. 146 * 147 * @param requestor the object requesting the clip data (not used) 148 * @return the current transferable object on the clipboard 149 * @throws IllegalStateException if the clipboard is currently unavailable 150 * @see java.awt.Toolkit#getSystemClipboard 151 */ 152 public synchronized Transferable getContents(Object requestor) { 153 return contents; 154 } 155 156 157 /** 158 * Returns an array of <code>DataFlavor</code>s in which the current 159 * contents of this clipboard can be provided. If there are no 160 * <code>DataFlavor</code>s available, this method returns a zero-length 161 * array. 162 * 163 * @return an array of <code>DataFlavor</code>s in which the current 164 * contents of this clipboard can be provided 165 * 166 * @throws IllegalStateException if this clipboard is currently unavailable 167 * 168 * @since 1.5 169 */ 170 public DataFlavor[] getAvailableDataFlavors() { 171 Transferable cntnts = getContents(null); 172 if (cntnts == null) { 173 return new DataFlavor[0]; 174 } 175 return cntnts.getTransferDataFlavors(); 176 } 177 178 /** 179 * Returns whether or not the current contents of this clipboard can be 180 * provided in the specified <code>DataFlavor</code>. 181 * 182 * @param flavor the requested <code>DataFlavor</code> for the contents 183 * 184 * @return <code>true</code> if the current contents of this clipboard 185 * can be provided in the specified <code>DataFlavor</code>; 186 * <code>false</code> otherwise 187 * 188 * @throws NullPointerException if <code>flavor</code> is <code>null</code> 189 * @throws IllegalStateException if this clipboard is currently unavailable 190 * 191 * @since 1.5 192 */ 193 public boolean isDataFlavorAvailable(DataFlavor flavor) { 194 if (flavor == null) { 195 throw new NullPointerException("flavor"); 196 } 197 198 Transferable cntnts = getContents(null); 199 if (cntnts == null) { 200 return false; 201 } 202 return cntnts.isDataFlavorSupported(flavor); 203 } 204 205 /** 206 * Returns an object representing the current contents of this clipboard 207 * in the specified <code>DataFlavor</code>. 208 * The class of the object returned is defined by the representation 209 * class of <code>flavor</code>. 210 * 211 * @param flavor the requested <code>DataFlavor</code> for the contents 212 * 213 * @return an object representing the current contents of this clipboard 214 * in the specified <code>DataFlavor</code> 215 * 216 * @throws NullPointerException if <code>flavor</code> is <code>null</code> 217 * @throws IllegalStateException if this clipboard is currently unavailable 218 * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code> 219 * is not available 220 * @throws IOException if the data in the requested <code>DataFlavor</code> 221 * can not be retrieved 222 * 223 * @see DataFlavor#getRepresentationClass 224 * 225 * @since 1.5 226 */ 227 public Object getData(DataFlavor flavor) 228 throws UnsupportedFlavorException, IOException { 229 if (flavor == null) { 230 throw new NullPointerException("flavor"); 231 } 232 233 Transferable cntnts = getContents(null); 234 if (cntnts == null) { 235 throw new UnsupportedFlavorException(flavor); 236 } 237 return cntnts.getTransferData(flavor); 238 } 239 240 241 /** 242 * Registers the specified <code>FlavorListener</code> to receive 243 * <code>FlavorEvent</code>s from this clipboard. 244 * If <code>listener</code> is <code>null</code>, no exception 245 * is thrown and no action is performed. 246 * 247 * @param listener the listener to be added 248 * 249 * @see #removeFlavorListener 250 * @see #getFlavorListeners 251 * @see FlavorListener 252 * @see FlavorEvent 253 * @since 1.5 254 */ 255 public synchronized void addFlavorListener(FlavorListener listener) { 256 if (listener == null) { 257 return; 258 } 259 if (flavorListeners.isEmpty()) { 260 currentDataFlavors = getAvailableDataFlavorSet(); 261 } 262 flavorListeners.add(listener); 263 } 264 265 /** 266 * Removes the specified <code>FlavorListener</code> so that it no longer 267 * receives <code>FlavorEvent</code>s from this <code>Clipboard</code>. 268 * This method performs no function, nor does it throw an exception, if 269 * the listener specified by the argument was not previously added to this 270 * <code>Clipboard</code>. 271 * If <code>listener</code> is <code>null</code>, no exception 272 * is thrown and no action is performed. 273 * 274 * @param listener the listener to be removed 275 * 276 * @see #addFlavorListener 277 * @see #getFlavorListeners 278 * @see FlavorListener 279 * @see FlavorEvent 280 * @since 1.5 281 */ 282 public synchronized void removeFlavorListener(FlavorListener listener) { 283 if (listener == null) { 284 return; 285 } 286 flavorListeners.remove(listener); 287 } 288 289 /** 290 * Returns an array of all the <code>FlavorListener</code>s currently 291 * registered on this <code>Clipboard</code>. 292 * 293 * @return all of this clipboard's <code>FlavorListener</code>s or an empty 294 * array if no listeners are currently registered 295 * @see #addFlavorListener 296 * @see #removeFlavorListener 297 * @see FlavorListener 298 * @see FlavorEvent 299 * @since 1.5 300 */ 301 public synchronized FlavorListener[] getFlavorListeners() { 302 return flavorListeners.toArray(new FlavorListener[flavorListeners.size()]); 303 } 304 305 /** 306 * Checks change of the <code>DataFlavor</code>s and, if necessary, 307 * notifies all listeners that have registered interest for notification 308 * on <code>FlavorEvent</code>s. 309 * 310 * @since 1.5 311 */ 312 private void fireFlavorsChanged() { 313 Set<DataFlavor> prevDataFlavors = currentDataFlavors; 314 currentDataFlavors = getAvailableDataFlavorSet(); 315 if (Objects.equals(prevDataFlavors, currentDataFlavors)) { 316 return; 317 } 318 flavorListeners.forEach(listener -> 319 EventQueue.invokeLater(() -> 320 listener.flavorsChanged(new FlavorEvent(Clipboard.this)))); 321 } 322 323 /** 324 * Returns a set of <code>DataFlavor</code>s currently available 325 * on this clipboard. 326 * 327 * @return a set of <code>DataFlavor</code>s currently available 328 * on this clipboard 329 * 330 * @since 1.5 331 */ 332 private Set<DataFlavor> getAvailableDataFlavorSet() { 333 Set<DataFlavor> set = new HashSet<>(); 334 Transferable contents = getContents(null); 335 if (contents != null) { 336 DataFlavor[] flavors = contents.getTransferDataFlavors(); 337 if (flavors != null) { 338 set.addAll(Arrays.asList(flavors)); 339 } 340 } 341 return set; 342 } 343 }