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 sun.datatransfer.DataFlavorUtil;

    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 Set<FlavorListener> flavorListeners;

    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             DataFlavorUtil.getDesktopService().invokeOnEventThread(() ->

   134                     oldOwner.lostOwnership(Clipboard.this, oldContents));

   135         }

   136         fireFlavorsChanged();

   137     }

   138 

   139     /**

   140      * Returns a transferable object representing the current contents

   141      * of the clipboard.  If the clipboard currently has no contents,

   142      * it returns <code>null</code>. The parameter Object requestor is

   143      * not currently used.  The method throws

   144      * <code>IllegalStateException</code> if the clipboard is currently

   145      * unavailable.  For example, on some platforms, the system clipboard is

   146      * unavailable while it is accessed by another application.

   147      *

   148      * @param requestor the object requesting the clip data  (not used)

   149      * @return the current transferable object on the clipboard

   150      * @throws IllegalStateException if the clipboard is currently unavailable

   151      * @see java.awt.Toolkit#getSystemClipboard

   152      */

   153     public synchronized Transferable getContents(Object requestor) {

   154         return contents;

   155     }

   156 

   157 

   158     /**

   159      * Returns an array of <code>DataFlavor</code>s in which the current

   160      * contents of this clipboard can be provided. If there are no

   161      * <code>DataFlavor</code>s available, this method returns a zero-length

   162      * array.

   163      *

   164      * @return an array of <code>DataFlavor</code>s in which the current

   165      *         contents of this clipboard can be provided

   166      *

   167      * @throws IllegalStateException if this clipboard is currently unavailable

   168      *

   169      * @since 1.5

   170      */

   171     public DataFlavor[] getAvailableDataFlavors() {

   172         Transferable cntnts = getContents(null);

   173         if (cntnts == null) {

   174             return new DataFlavor[0];

   175         }

   176         return cntnts.getTransferDataFlavors();

   177     }

   178 

   179     /**

   180      * Returns whether or not the current contents of this clipboard can be

   181      * provided in the specified <code>DataFlavor</code>.

   182      *

   183      * @param flavor the requested <code>DataFlavor</code> for the contents

   184      *

   185      * @return <code>true</code> if the current contents of this clipboard

   186      *         can be provided in the specified <code>DataFlavor</code>;

   187      *         <code>false</code> otherwise

   188      *

   189      * @throws NullPointerException if <code>flavor</code> is <code>null</code>

   190      * @throws IllegalStateException if this clipboard is currently unavailable

   191      *

   192      * @since 1.5

   193      */

   194     public boolean isDataFlavorAvailable(DataFlavor flavor) {

   195         if (flavor == null) {

   196             throw new NullPointerException("flavor");

   197         }

   198 

   199         Transferable cntnts = getContents(null);

   200         if (cntnts == null) {

   201             return false;

   202         }

   203         return cntnts.isDataFlavorSupported(flavor);

   204     }

   205 

   206     /**

   207      * Returns an object representing the current contents of this clipboard

   208      * in the specified <code>DataFlavor</code>.

   209      * The class of the object returned is defined by the representation

   210      * class of <code>flavor</code>.

   211      *

   212      * @param flavor the requested <code>DataFlavor</code> for the contents

   213      *

   214      * @return an object representing the current contents of this clipboard

   215      *         in the specified <code>DataFlavor</code>

   216      *

   217      * @throws NullPointerException if <code>flavor</code> is <code>null</code>

   218      * @throws IllegalStateException if this clipboard is currently unavailable

   219      * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code>

   220      *         is not available

   221      * @throws IOException if the data in the requested <code>DataFlavor</code>

   222      *         can not be retrieved

   223      *

   224      * @see DataFlavor#getRepresentationClass

   225      *

   226      * @since 1.5

   227      */

   228     public Object getData(DataFlavor flavor)

   229         throws UnsupportedFlavorException, IOException {

   230         if (flavor == null) {

   231             throw new NullPointerException("flavor");

   232         }

   233 

   234         Transferable cntnts = getContents(null);

   235         if (cntnts == null) {

   236             throw new UnsupportedFlavorException(flavor);

   237         }

   238         return cntnts.getTransferData(flavor);

   239     }

   240 

   241 

   242     /**

   243      * Registers the specified <code>FlavorListener</code> to receive

   244      * <code>FlavorEvent</code>s from this clipboard.

   245      * If <code>listener</code> is <code>null</code>, no exception

   246      * is thrown and no action is performed.

   247      *

   248      * @param listener the listener to be added

   249      *

   250      * @see #removeFlavorListener

   251      * @see #getFlavorListeners

   252      * @see FlavorListener

   253      * @see FlavorEvent

   254      * @since 1.5

   255      */

   256     public synchronized void addFlavorListener(FlavorListener listener) {

   257         if (listener == null) {

   258             return;

   259         }

   260 

   261         if (flavorListeners == null) {

   262             flavorListeners = new HashSet<>();

   263             currentDataFlavors = getAvailableDataFlavorSet();

   264         }

   265 

   266         flavorListeners.add(listener);

   267     }

   268 

   269     /**

   270      * Removes the specified <code>FlavorListener</code> so that it no longer

   271      * receives <code>FlavorEvent</code>s from this <code>Clipboard</code>.

   272      * This method performs no function, nor does it throw an exception, if

   273      * the listener specified by the argument was not previously added to this

   274      * <code>Clipboard</code>.

   275      * If <code>listener</code> is <code>null</code>, no exception

   276      * is thrown and no action is performed.

   277      *

   278      * @param listener the listener to be removed

   279      *

   280      * @see #addFlavorListener

   281      * @see #getFlavorListeners

   282      * @see FlavorListener

   283      * @see FlavorEvent

   284      * @since 1.5

   285      */

   286     public synchronized void removeFlavorListener(FlavorListener listener) {

   287         if (listener == null || flavorListeners == null) {

   288             return;

   289         }

   290         flavorListeners.remove(listener);

   291     }

   292 

   293     /**

   294      * Returns an array of all the <code>FlavorListener</code>s currently

   295      * registered on this <code>Clipboard</code>.

   296      *

   297      * @return all of this clipboard's <code>FlavorListener</code>s or an empty

   298      *         array if no listeners are currently registered

   299      * @see #addFlavorListener

   300      * @see #removeFlavorListener

   301      * @see FlavorListener

   302      * @see FlavorEvent

   303      * @since 1.5

   304      */

   305     public synchronized FlavorListener[] getFlavorListeners() {

   306         return flavorListeners == null ? new FlavorListener[0] :

   307             flavorListeners.toArray(new FlavorListener[flavorListeners.size()]);

   308     }

   309 

   310     /**

   311      * Checks change of the <code>DataFlavor</code>s and, if necessary,

   312      * notifies all listeners that have registered interest for notification

   313      * on <code>FlavorEvent</code>s.

   314      *

   315      * @since 1.5

   316      */

   317     private void fireFlavorsChanged() {

   318         if (flavorListeners == null) {

   319             return;

   320         }

   321 

   322         Set<DataFlavor> prevDataFlavors = currentDataFlavors;

   323         currentDataFlavors = getAvailableDataFlavorSet();

   324         if (Objects.equals(prevDataFlavors, currentDataFlavors)) {

   325             return;

   326         }

   327         flavorListeners.forEach(listener ->

   328                 DataFlavorUtil.getDesktopService().invokeOnEventThread(() ->

   329                         listener.flavorsChanged(new FlavorEvent(Clipboard.this))));

   330     }

   331 

   332     /**

   333      * Returns a set of <code>DataFlavor</code>s currently available

   334      * on this clipboard.

   335      *

   336      * @return a set of <code>DataFlavor</code>s currently available

   337      *         on this clipboard

   338      *

   339      * @since 1.5

   340      */

   341     private Set<DataFlavor> getAvailableDataFlavorSet() {

   342         Set<DataFlavor> set = new HashSet<>();

   343         Transferable contents = getContents(null);

   344         if (contents != null) {

   345             DataFlavor[] flavors = contents.getTransferDataFlavors();

   346             if (flavors != null) {

   347                 set.addAll(Arrays.asList(flavors));

   348             }

   349         }

   350         return set;

   351     }

   352 }