src/java.datatransfer/share/classes/java/awt/datatransfer/Clipboard.java
changeset 47216 71c04702a3d5
parent 45655 02c95aa8a53a
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/java.datatransfer/share/classes/java/awt/datatransfer/Clipboard.java	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,331 @@
+/*
+ * Copyright (c) 1996, 2017, 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.
+ * <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}).
+ *
+ * @author Amy Fowler
+ * @author Alexander Gerasimov
+ * @see java.awt.Toolkit#getSystemClipboard
+ * @see java.awt.Toolkit#getSystemSelection
+ * @since 1.1
+ */
+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<FlavorListener> 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<DataFlavor> currentDataFlavors;
+
+    /**
+     * Creates a clipboard object.
+     *
+     * @param  name for the clipboard
+     * @see 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.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},
+     * 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.
+     * <p>
+     * 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.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.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<DataFlavor> 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<DataFlavor> getAvailableDataFlavorSet() {
+        Set<DataFlavor> set = new HashSet<>();
+        Transferable contents = getContents(null);
+        if (contents != null) {
+            DataFlavor[] flavors = contents.getTransferDataFlavors();
+            if (flavors != null) {
+                set.addAll(Arrays.asList(flavors));
+            }
+        }
+        return set;
+    }
+}