* {@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 DataFlavors that is available on
* this local clipboard. It is used for tracking changes
* of DataFlavors 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.
*
* If there is an existing owner different from the argument
* owner, that owner is notified that it no longer
* holds ownership of the clipboard contents via an invocation
* of ClipboardOwner.lostOwnership() on that owner.
* An implementation of setContents() is free not
* to invoke lostOwnership() directly from this method.
* For example, lostOwnership() may be invoked later on
* a different thread. The same applies to FlavorListeners
* registered on this clipboard.
*
* The method throws 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) {
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 null. The parameter Object requestor is
* not currently used. The method throws
* 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 DataFlavors in which the current
* contents of this clipboard can be provided. If there are no
* DataFlavors available, this method returns a zero-length
* array.
*
* @return an array of DataFlavors 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 DataFlavor.
*
* @param flavor the requested DataFlavor for the contents
*
* @return true if the current contents of this clipboard
* can be provided in the specified DataFlavor;
* false otherwise
*
* @throws NullPointerException if flavor is 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 DataFlavor.
* The class of the object returned is defined by the representation
* class of flavor.
*
* @param flavor the requested DataFlavor for the contents
*
* @return an object representing the current contents of this clipboard
* in the specified DataFlavor
*
* @throws NullPointerException if flavor is null
* @throws IllegalStateException if this clipboard is currently unavailable
* @throws UnsupportedFlavorException if the requested DataFlavor
* is not available
* @throws IOException if the data in the requested 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 FlavorListener to receive
* FlavorEvents from this clipboard.
* If listener is 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) {
currentDataFlavors = getAvailableDataFlavorSet();
flavorListeners = new EventListenerAggregate(FlavorListener.class);
}
flavorListeners.add(listener);
}
/**
* Removes the specified FlavorListener so that it no longer
* receives FlavorEvents from this 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
* Clipboard.
* If listener is 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 FlavorListeners currently
* registered on this Clipboard.
*
* @return all of this clipboard's FlavorListeners 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 DataFlavors and, if necessary,
* notifies all listeners that have registered interest for notification
* on FlavorEvents.
*
* @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 DataFlavors currently available
* on this clipboard.
*
* @return a set of DataFlavors 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;
}
}