/* * Copyright (c) 1996, 2022, 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.io.IOException; import java.util.Arrays; import java.util.HashSet; import java.util.Objects; import java.util.Set; import sun.datatransfer.DataFlavorUtil; /** * A class that implements a mechanism to transfer data using cut/copy/paste * operations. *

* {@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}). * * @author Amy Fowler * @author Alexander Gerasimov * @see java.desktop/java.awt.Toolkit#getSystemClipboard * @see java.desktop/java.awt.Toolkit#getSystemSelection * @since 1.1 */ @SuppressWarnings("doclint:reference") // cross-module links public class Clipboard { String name; /** * The owner of the clipboard. */ protected ClipboardOwner owner; /** * Contents of the clipboard. */ protected Transferable contents; /** * An aggregate of flavor listeners registered on this local clipboard. * * @since 1.5 */ private Set flavorListeners; /** * A set of {@code DataFlavor}s that is available on this local clipboard. * It is used for tracking changes of {@code DataFlavor}s available on this * clipboard. * * @since 1.5 */ private Set currentDataFlavors; /** * Creates a clipboard object. * * @param name for the clipboard * @see java.desktop/java.awt.Toolkit#getSystemClipboard */ public Clipboard(String name) { this.name = name; } /** * Returns the name of this clipboard object. * * @return the name of this clipboard object * @see java.desktop/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. *

* If there is an existing owner different from the argument {@code owner}, * that owner is notified that it no longer holds ownership of the clipboard * contents via an invocation of {@code ClipboardOwner.lostOwnership()} on * that owner. An implementation of {@code setContents()} is free not to * invoke {@code lostOwnership()} directly from this method. For example, * {@code lostOwnership()} may be invoked later on a different thread. The * same applies to {@code FlavorListener}s registered on this clipboard. *

* The method throws {@code IllegalStateException} 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.desktop/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) { DataFlavorUtil.getDesktopService().invokeOnEventThread(() -> 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}. The parameter Object requestor is not currently used. The * method throws {@code IllegalStateException} 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.desktop/java.awt.Toolkit#getSystemClipboard */ public synchronized Transferable getContents(Object requestor) { return contents; } /** * Returns an array of {@code DataFlavor}s in which the current contents of * this clipboard can be provided. If there are no {@code DataFlavor}s * available, this method returns a zero-length array. * * @return an array of {@code DataFlavor}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}. * * @param flavor the requested {@code DataFlavor} for the contents * @return {@code true} if the current contents of this clipboard can be * provided in the specified {@code DataFlavor}; {@code false} * otherwise * @throws NullPointerException if {@code flavor} is {@code null} * @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}. The class of the object returned is * defined by the representation class of {@code flavor}. * * @param flavor the requested {@code DataFlavor} for the contents * @return an object representing the current contents of this clipboard in * the specified {@code DataFlavor} * @throws NullPointerException if {@code flavor} is {@code null} * @throws IllegalStateException if this clipboard is currently unavailable * @throws UnsupportedFlavorException if the requested {@code DataFlavor} is * not available * @throws IOException if the data in the requested {@code DataFlavor} 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} to receive * {@code FlavorEvent}s from this clipboard. If {@code listener} is * {@code null}, 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) { flavorListeners = new HashSet<>(); currentDataFlavors = getAvailableDataFlavorSet(); } flavorListeners.add(listener); } /** * Removes the specified {@code FlavorListener} so that it no longer * receives {@code FlavorEvent}s from this {@code Clipboard}. 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}. If {@code listener} is {@code null}, 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}s currently registered * on this {@code Clipboard}. * * @return all of this clipboard's {@code FlavorListener}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] : flavorListeners.toArray(new FlavorListener[flavorListeners.size()]); } /** * Checks change of the {@code DataFlavor}s and, if necessary, notifies all * listeners that have registered interest for notification on * {@code FlavorEvent}s. * * @since 1.5 */ private void fireFlavorsChanged() { if (flavorListeners == null) { return; } Set prevDataFlavors = currentDataFlavors; currentDataFlavors = getAvailableDataFlavorSet(); if (Objects.equals(prevDataFlavors, currentDataFlavors)) { return; } flavorListeners.forEach(listener -> DataFlavorUtil.getDesktopService().invokeOnEventThread(() -> listener.flavorsChanged(new FlavorEvent(Clipboard.this)))); } /** * Returns a set of {@code DataFlavor}s currently available on this * clipboard. * * @return a set of {@code DataFlavor}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; } }