/* * Copyright (c) 1996, 2006, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation.  Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt.datatransfer; import java.awt.EventQueue; import java.util.Set;import java.util.HashSet;import java.util.Arrays; import java.io.IOException; import sun.awt.EventListenerAggregate;  /** * A class that implements a mechanism to transfer data using * cut/copy/paste operations. * <p> * {@link FlavorListener}s may be registered on an instance of the * Clipboard class to be notified about changes to the set of * {@link DataFlavor}s available on this clipboard (see * {@link #addFlavorListener}). * * @see java.awt.Toolkit#getSystemClipboard * @see java.awt.Toolkit#getSystemSelection * * @author      Amy Fowler * @author      Alexander Gerasimov */public class Clipboard {     String name;     protected ClipboardOwner owner;    protected Transferable contents;     /**     * An aggregate of flavor listeners registered on this local clipboard.     *     * @since 1.5     */    private EventListenerAggregate flavorListeners;     /**     * A set of <code>DataFlavor</code>s that is available on     * this local clipboard. It is used for tracking changes     * of <code>DataFlavor</code>s available on this clipboard.     *     * @since 1.5     */    private Set currentDataFlavors;     /**     * Creates a clipboard object.     *     * @see java.awt.Toolkit#getSystemClipboard     */    public Clipboard(String name) {        this.name = name;    }     /**     * Returns the name of this clipboard object.     *     * @see java.awt.Toolkit#getSystemClipboard     */    public String getName() {        return name;    }     /**     * Sets the current contents of the clipboard to the specified     * transferable object and registers the specified clipboard owner     * as the owner of the new contents.     * <p>     * If there is an existing owner different from the argument     * <code>owner</code>, that owner is notified that it no longer     * holds ownership of the clipboard contents via an invocation     * of <code>ClipboardOwner.lostOwnership()</code> on that owner.     * An implementation of <code>setContents()</code> is free not     * to invoke <code>lostOwnership()</code> directly from this method.     * For example, <code>lostOwnership()</code> may be invoked later on     * a different thread. The same applies to <code>FlavorListener</code>s     * registered on this clipboard.     * <p>     * The method throws <code>IllegalStateException</code> if the clipboard     * is currently unavailable. For example, on some platforms, the system     * clipboard is unavailable while it is accessed by another application.     *     * @param contents the transferable object representing the     *                 clipboard content     * @param owner the object which owns the clipboard content     * @throws IllegalStateException if the clipboard is currently unavailable     * @see java.awt.Toolkit#getSystemClipboard     */    public synchronized void setContents(Transferable contents, ClipboardOwner owner) {        final ClipboardOwner oldOwner = this.owner;        final Transferable oldContents = this.contents;         this.owner = owner;        this.contents = contents;         if (oldOwner != null && oldOwner != owner) {            EventQueue.invokeLater(new Runnable() {                public void run() {                    oldOwner.lostOwnership(Clipboard.this, oldContents);                }            });        }        fireFlavorsChanged();    }     /**     * Returns a transferable object representing the current contents     * of the clipboard.  If the clipboard currently has no contents,     * it returns <code>null</code>. The parameter Object requestor is     * not currently used.  The method throws     * <code>IllegalStateException</code> if the clipboard is currently     * unavailable.  For example, on some platforms, the system clipboard is     * unavailable while it is accessed by another application.     *     * @param requestor the object requesting the clip data  (not used)     * @return the current transferable object on the clipboard     * @throws IllegalStateException if the clipboard is currently unavailable     * @see java.awt.Toolkit#getSystemClipboard     */    public synchronized Transferable getContents(Object requestor) {        return contents;    }      /**     * Returns an array of <code>DataFlavor</code>s in which the current     * contents of this clipboard can be provided. If there are no     * <code>DataFlavor</code>s available, this method returns a zero-length     * array.     *     * @return an array of <code>DataFlavor</code>s in which the current     *         contents of this clipboard can be provided     *     * @throws IllegalStateException if this clipboard is currently unavailable     *     * @since 1.5     */    public DataFlavor[] getAvailableDataFlavors() {        Transferable cntnts = getContents(null);        if (cntnts == null) {            return new DataFlavor[0];        }        return cntnts.getTransferDataFlavors();    }     /**     * Returns whether or not the current contents of this clipboard can be     * provided in the specified <code>DataFlavor</code>.     *     * @param flavor the requested <code>DataFlavor</code> for the contents     *     * @return <code>true</code> if the current contents of this clipboard     *         can be provided in the specified <code>DataFlavor</code>;     *         <code>false</code> otherwise     *     * @throws NullPointerException if <code>flavor</code> is <code>null</code>     * @throws IllegalStateException if this clipboard is currently unavailable     *     * @since 1.5     */    public boolean isDataFlavorAvailable(DataFlavor flavor) {        if (flavor == null) {            throw new NullPointerException("flavor");        }         Transferable cntnts = getContents(null);        if (cntnts == null) {            return false;        }        return cntnts.isDataFlavorSupported(flavor);    }     /**     * Returns an object representing the current contents of this clipboard     * in the specified <code>DataFlavor</code>.     * The class of the object returned is defined by the representation     * class of <code>flavor</code>.     *     * @param flavor the requested <code>DataFlavor</code> for the contents     *     * @return an object representing the current contents of this clipboard     *         in the specified <code>DataFlavor</code>     *     * @throws NullPointerException if <code>flavor</code> is <code>null</code>     * @throws IllegalStateException if this clipboard is currently unavailable     * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code>     *         is not available     * @throws IOException if the data in the requested <code>DataFlavor</code>     *         can not be retrieved     *     * @see DataFlavor#getRepresentationClass     *     * @since 1.5     */    public Object getData(DataFlavor flavor)        throws UnsupportedFlavorException, IOException {        if (flavor == null) {            throw new NullPointerException("flavor");        }         Transferable cntnts = getContents(null);        if (cntnts == null) {            throw new UnsupportedFlavorException(flavor);        }        return cntnts.getTransferData(flavor);    }      /**     * Registers the specified <code>FlavorListener</code> to receive     * <code>FlavorEvent</code>s from this clipboard.     * If <code>listener</code> is <code>null</code>, no exception     * is thrown and no action is performed.     *     * @param listener the listener to be added     *     * @see #removeFlavorListener     * @see #getFlavorListeners     * @see FlavorListener     * @see FlavorEvent     * @since 1.5     */    public synchronized void addFlavorListener(FlavorListener listener) {        if (listener == null) {            return;        }        if (flavorListeners == null) {            currentDataFlavors = getAvailableDataFlavorSet();            flavorListeners = new EventListenerAggregate(FlavorListener.class);        }        flavorListeners.add(listener);    }     /**     * Removes the specified <code>FlavorListener</code> so that it no longer     * receives <code>FlavorEvent</code>s from this <code>Clipboard</code>.     * This method performs no function, nor does it throw an exception, if     * the listener specified by the argument was not previously added to this     * <code>Clipboard</code>.     * If <code>listener</code> is <code>null</code>, no exception     * is thrown and no action is performed.     *     * @param listener the listener to be removed     *     * @see #addFlavorListener     * @see #getFlavorListeners     * @see FlavorListener     * @see FlavorEvent     * @since 1.5     */    public synchronized void removeFlavorListener(FlavorListener listener) {        if (listener == null || flavorListeners == null) {            return;        }        flavorListeners.remove(listener);    }     /**     * Returns an array of all the <code>FlavorListener</code>s currently     * registered on this <code>Clipboard</code>.     *     * @return all of this clipboard's <code>FlavorListener</code>s or an empty     *         array if no listeners are currently registered     * @see #addFlavorListener     * @see #removeFlavorListener     * @see FlavorListener     * @see FlavorEvent     * @since 1.5     */    public synchronized FlavorListener[] getFlavorListeners() {        return flavorListeners == null ? new FlavorListener[0] :                (FlavorListener[])flavorListeners.getListenersCopy();    }     /**     * Checks change of the <code>DataFlavor</code>s and, if necessary,     * notifies all listeners that have registered interest for notification     * on <code>FlavorEvent</code>s.     *     * @since 1.5     */    private void fireFlavorsChanged() {        if (flavorListeners == null) {            return;        }        Set prevDataFlavors = currentDataFlavors;        currentDataFlavors = getAvailableDataFlavorSet();        if (prevDataFlavors.equals(currentDataFlavors)) {            return;        }        FlavorListener[] flavorListenerArray =                (FlavorListener[])flavorListeners.getListenersInternal();        for (int i = 0; i < flavorListenerArray.length; i++) {            final FlavorListener listener = flavorListenerArray[i];            EventQueue.invokeLater(new Runnable() {                public void run() {                    listener.flavorsChanged(new FlavorEvent(Clipboard.this));                }            });        }    }     /**     * Returns a set of <code>DataFlavor</code>s currently available     * on this clipboard.     *     * @return a set of <code>DataFlavor</code>s currently available     *         on this clipboard     *     * @since 1.5     */    private Set getAvailableDataFlavorSet() {        Set set = new HashSet();        Transferable contents = getContents(null);        if (contents != null) {            DataFlavor[] flavors = contents.getTransferDataFlavors();            if (flavors != null) {                set.addAll(Arrays.asList(flavors));            }        }        return set;    }}