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.Set;
31 import java.util.HashSet;
32 import java.util.Arrays;
33
34 import java.io.IOException;
35
36 /**
37 * A class that implements a mechanism to transfer data using
38 * cut/copy/paste operations.
39 * <p>
40 * {@link FlavorListener}s may be registered on an instance of the
41 * Clipboard class to be notified about changes to the set of
42 * {@link DataFlavor}s available on this clipboard (see
43 * {@link #addFlavorListener}).
44 *
45 * @see java.awt.Toolkit#getSystemClipboard
46 * @see java.awt.Toolkit#getSystemSelection
47 *
48 * @author Amy Fowler
49 * @author Alexander Gerasimov
50 */
51 public class Clipboard {
52
53 String name;
54
55 /**
56 * The owner of the clipboard.
57 */
58 protected ClipboardOwner owner;
59 /**
60 * Contents of the clipboard.
61 */
62 protected Transferable contents;
63
64 /**
65 * An aggregate of flavor listeners registered on this local clipboard.
66 *
67 * @since 1.5
68 */
69 private final Set<FlavorListener> flavorListeners = new HashSet<>();
70
71 /**
72 * A set of <code>DataFlavor</code>s that is available on
73 * this local clipboard. It is used for tracking changes
74 * of <code>DataFlavor</code>s available on this clipboard.
75 *
76 * @since 1.5
77 */
78 private Set<DataFlavor> currentDataFlavors;
79
80 /**
81 * Creates a clipboard object.
82 * @param name for the clipboard
83 * @see java.awt.Toolkit#getSystemClipboard
84 */
85 public Clipboard(String name) {
86 this.name = name;
87 }
88
89 /**
90 * Returns the name of this clipboard object.
91 * @return the name of this clipboard object
92 *
93 * @see java.awt.Toolkit#getSystemClipboard
94 */
95 public String getName() {
96 return name;
97 }
98
99 /**
100 * Sets the current contents of the clipboard to the specified
101 * transferable object and registers the specified clipboard owner
102 * as the owner of the new contents.
103 * <p>
104 * If there is an existing owner different from the argument
105 * <code>owner</code>, that owner is notified that it no longer
106 * holds ownership of the clipboard contents via an invocation
107 * of <code>ClipboardOwner.lostOwnership()</code> on that owner.
108 * An implementation of <code>setContents()</code> is free not
109 * to invoke <code>lostOwnership()</code> directly from this method.
110 * For example, <code>lostOwnership()</code> may be invoked later on
111 * a different thread. The same applies to <code>FlavorListener</code>s
112 * registered on this clipboard.
113 * <p>
114 * The method throws <code>IllegalStateException</code> if the clipboard
115 * is currently unavailable. For example, on some platforms, the system
116 * clipboard is unavailable while it is accessed by another application.
117 *
118 * @param contents the transferable object representing the
119 * clipboard content
120 * @param owner the object which owns the clipboard content
121 * @throws IllegalStateException if the clipboard is currently unavailable
122 * @see java.awt.Toolkit#getSystemClipboard
123 */
124 public synchronized void setContents(Transferable contents, ClipboardOwner owner) {
125 final ClipboardOwner oldOwner = this.owner;
126 final Transferable oldContents = this.contents;
127
128 this.owner = owner;
129 this.contents = contents;
130
131 if (oldOwner != null && oldOwner != owner) {
132 EventQueue.invokeLater(() -> oldOwner.lostOwnership(Clipboard.this, oldContents));
133 }
134 fireFlavorsChanged();
135 }
136
137 /**
138 * Returns a transferable object representing the current contents
139 * of the clipboard. If the clipboard currently has no contents,
140 * it returns <code>null</code>. The parameter Object requestor is
141 * not currently used. The method throws
142 * <code>IllegalStateException</code> if the clipboard is currently
143 * unavailable. For example, on some platforms, the system clipboard is
144 * unavailable while it is accessed by another application.
145 *
146 * @param requestor the object requesting the clip data (not used)
147 * @return the current transferable object on the clipboard
148 * @throws IllegalStateException if the clipboard is currently unavailable
149 * @see java.awt.Toolkit#getSystemClipboard
150 */
151 public synchronized Transferable getContents(Object requestor) {
152 return contents;
153 }
154
155
156 /**
157 * Returns an array of <code>DataFlavor</code>s in which the current
158 * contents of this clipboard can be provided. If there are no
159 * <code>DataFlavor</code>s available, this method returns a zero-length
160 * array.
161 *
162 * @return an array of <code>DataFlavor</code>s in which the current
163 * contents of this clipboard can be provided
164 *
165 * @throws IllegalStateException if this clipboard is currently unavailable
166 *
167 * @since 1.5
168 */
169 public DataFlavor[] getAvailableDataFlavors() {
170 Transferable cntnts = getContents(null);
171 if (cntnts == null) {
172 return new DataFlavor[0];
173 }
174 return cntnts.getTransferDataFlavors();
175 }
176
177 /**
178 * Returns whether or not the current contents of this clipboard can be
179 * provided in the specified <code>DataFlavor</code>.
180 *
181 * @param flavor the requested <code>DataFlavor</code> for the contents
182 *
183 * @return <code>true</code> if the current contents of this clipboard
184 * can be provided in the specified <code>DataFlavor</code>;
185 * <code>false</code> otherwise
186 *
187 * @throws NullPointerException if <code>flavor</code> is <code>null</code>
188 * @throws IllegalStateException if this clipboard is currently unavailable
189 *
190 * @since 1.5
191 */
192 public boolean isDataFlavorAvailable(DataFlavor flavor) {
193 if (flavor == null) {
194 throw new NullPointerException("flavor");
195 }
196
197 Transferable cntnts = getContents(null);
198 if (cntnts == null) {
199 return false;
200 }
201 return cntnts.isDataFlavorSupported(flavor);
202 }
203
204 /**
205 * Returns an object representing the current contents of this clipboard
206 * in the specified <code>DataFlavor</code>.
207 * The class of the object returned is defined by the representation
208 * class of <code>flavor</code>.
209 *
210 * @param flavor the requested <code>DataFlavor</code> for the contents
211 *
212 * @return an object representing the current contents of this clipboard
213 * in the specified <code>DataFlavor</code>
214 *
215 * @throws NullPointerException if <code>flavor</code> is <code>null</code>
216 * @throws IllegalStateException if this clipboard is currently unavailable
217 * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code>
218 * is not available
219 * @throws IOException if the data in the requested <code>DataFlavor</code>
220 * can not be retrieved
221 *
222 * @see DataFlavor#getRepresentationClass
223 *
224 * @since 1.5
225 */
226 public Object getData(DataFlavor flavor)
227 throws UnsupportedFlavorException, IOException {
228 if (flavor == null) {
229 throw new NullPointerException("flavor");
230 }
231
232 Transferable cntnts = getContents(null);
233 if (cntnts == null) {
234 throw new UnsupportedFlavorException(flavor);
235 }
236 return cntnts.getTransferData(flavor);
237 }
238
239
240 /**
241 * Registers the specified <code>FlavorListener</code> to receive
242 * <code>FlavorEvent</code>s from this clipboard.
243 * If <code>listener</code> is <code>null</code>, no exception
244 * is thrown and no action is performed.
245 *
246 * @param listener the listener to be added
247 *
248 * @see #removeFlavorListener
249 * @see #getFlavorListeners
250 * @see FlavorListener
251 * @see FlavorEvent
252 * @since 1.5
253 */
254 public synchronized void addFlavorListener(FlavorListener listener) {
255 if (listener == null) {
256 return;
257 }
258 if (flavorListeners.isEmpty()) {
259 currentDataFlavors = getAvailableDataFlavorSet();
260 }
261 flavorListeners.add(listener);
262 }
263
264 /**
265 * Removes the specified <code>FlavorListener</code> so that it no longer
266 * receives <code>FlavorEvent</code>s from this <code>Clipboard</code>.
267 * This method performs no function, nor does it throw an exception, if
268 * the listener specified by the argument was not previously added to this
269 * <code>Clipboard</code>.
270 * If <code>listener</code> is <code>null</code>, no exception
271 * is thrown and no action is performed.
272 *
273 * @param listener the listener to be removed
274 *
275 * @see #addFlavorListener
276 * @see #getFlavorListeners
277 * @see FlavorListener
278 * @see FlavorEvent
279 * @since 1.5
280 */
281 public synchronized void removeFlavorListener(FlavorListener listener) {
282 if (listener == null) {
283 return;
284 }
285 flavorListeners.remove(listener);
286 }
287
288 /**
289 * Returns an array of all the <code>FlavorListener</code>s currently
290 * registered on this <code>Clipboard</code>.
291 *
292 * @return all of this clipboard's <code>FlavorListener</code>s or an empty
293 * array if no listeners are currently registered
294 * @see #addFlavorListener
295 * @see #removeFlavorListener
296 * @see FlavorListener
297 * @see FlavorEvent
298 * @since 1.5
299 */
300 public synchronized FlavorListener[] getFlavorListeners() {
301 return flavorListeners.toArray(new FlavorListener[flavorListeners.size()]);
302 }
303
304 /**
305 * Checks change of the <code>DataFlavor</code>s and, if necessary,
306 * notifies all listeners that have registered interest for notification
307 * on <code>FlavorEvent</code>s.
308 *
309 * @since 1.5
310 */
311 private void fireFlavorsChanged() {
312 Set<DataFlavor> prevDataFlavors = currentDataFlavors;
313 currentDataFlavors = getAvailableDataFlavorSet();
314 if (prevDataFlavors != null && currentDataFlavors != null
315 && prevDataFlavors.equals(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 }