SystemTray class represents the system tray for a
* desktop. On Microsoft Windows it is referred to as the "Taskbar
* Status Area", on Gnome it is referred to as the "Notification
* Area", on KDE it is referred to as the "System Tray". The system
* tray is shared by all applications running on the desktop.
*
* On some platforms the system tray may not be present or may not * be supported, in this case {@link SystemTray#getSystemTray()} * throws {@link UnsupportedOperationException}. To detect whether the * system tray is supported, use {@link SystemTray#isSupported}. * *
The SystemTray may contain one or more {@link
* TrayIcon TrayIcons}, which are added to the tray using the {@link
* #add} method, and removed when no longer needed, using the
* {@link #remove}. TrayIcon consists of an
* image, a popup menu and a set of associated listeners. Please see
* the {@link TrayIcon} class for details.
*
*
Every Java application has a single SystemTray
* instance that allows the app to interface with the system tray of
* the desktop while the app is running. The SystemTray
* instance can be obtained from the {@link #getSystemTray} method.
* An application may not create its own instance of
* SystemTray.
*
*
The following code snippet demonstrates how to access
* and customize the system tray:
*
*
*
* @since 1.6
* @see TrayIcon
*
* @author Bino George
* @author Denis Mikhalkin
* @author Sharon Zakhour
* @author Anton Tarasov
*/
public class SystemTray {
private static SystemTray systemTray;
private int currentIconID = 0; // each TrayIcon added gets a unique ID
transient private SystemTrayPeer peer;
private static final TrayIcon[] EMPTY_TRAY_ARRAY = new TrayIcon[0];
static {
AWTAccessor.setSystemTrayAccessor(
new AWTAccessor.SystemTrayAccessor() {
public void firePropertyChange(SystemTray tray,
String propertyName,
Object oldValue,
Object newValue) {
tray.firePropertyChange(propertyName, oldValue, newValue);
}
});
}
/**
* Private
* {@link TrayIcon} trayIcon = null;
* if (SystemTray.isSupported()) {
* // get the SystemTray instance
* SystemTray tray = SystemTray.{@link #getSystemTray};
* // load an image
* {@link java.awt.Image} image = {@link java.awt.Toolkit#getImage(String) Toolkit.getDefaultToolkit().getImage}(...);
* // create a action listener to listen for default action executed on the tray icon
* {@link java.awt.event.ActionListener} listener = new {@link java.awt.event.ActionListener ActionListener}() {
* public void {@link java.awt.event.ActionListener#actionPerformed actionPerformed}({@link java.awt.event.ActionEvent} e) {
* // execute default action of the application
* // ...
* }
* };
* // create a popup menu
* {@link java.awt.PopupMenu} popup = new {@link java.awt.PopupMenu#PopupMenu PopupMenu}();
* // create menu item for the default action
* MenuItem defaultItem = new MenuItem(...);
* defaultItem.addActionListener(listener);
* popup.add(defaultItem);
* /// ... add other items
* // construct a TrayIcon
* trayIcon = new {@link TrayIcon#TrayIcon(java.awt.Image, String, java.awt.PopupMenu) TrayIcon}(image, "Tray Demo", popup);
* // set the TrayIcon properties
* trayIcon.{@link TrayIcon#addActionListener(java.awt.event.ActionListener) addActionListener}(listener);
* // ...
* // add the tray image
* try {
* tray.{@link SystemTray#add(TrayIcon) add}(trayIcon);
* } catch (AWTException e) {
* System.err.println(e);
* }
* // ...
* } else {
* // disable tray option in your application or
* // perform other actions
* ...
* }
* // ...
* // some time later
* // the application state has changed - update the image
* if (trayIcon != null) {
* trayIcon.{@link TrayIcon#setImage(java.awt.Image) setImage}(updatedImage);
* }
* // ...
*
* SystemTray constructor.
*
*/
private SystemTray() {
addNotify();
}
/**
* Gets the SystemTray instance that represents the
* desktop's tray area. This always returns the same instance per
* application. On some platforms the system tray may not be
* supported. You may use the {@link #isSupported} method to
* check if the system tray is supported.
*
*
If a SecurityManager is installed, the AWTPermission
* {@code accessSystemTray} must be granted in order to get the
* {@code SystemTray} instance. Otherwise this method will throw a
* SecurityException.
*
* @return the SystemTray instance that represents
* the desktop's tray area
* @throws UnsupportedOperationException if the system tray isn't
* supported by the current platform
* @throws HeadlessException if
* GraphicsEnvironment.isHeadless() returns true
* @throws SecurityException if {@code accessSystemTray} permission
* is not granted
* @see #add(TrayIcon)
* @see TrayIcon
* @see #isSupported
* @see SecurityManager#checkPermission
* @see AWTPermission
*/
public static SystemTray getSystemTray() {
checkSystemTrayAllowed();
if (GraphicsEnvironment.isHeadless()) {
throw new HeadlessException();
}
initializeSystemTrayIfNeeded();
if (!isSupported()) {
throw new UnsupportedOperationException(
"The system tray is not supported on the current platform.");
}
return systemTray;
}
/**
* Returns whether the system tray is supported on the current
* platform. In addition to displaying the tray icon, minimal
* system tray support includes either a popup menu (see {@link
* TrayIcon#setPopupMenu(PopupMenu)}) or an action event (see
* {@link TrayIcon#addActionListener(ActionListener)}).
*
*
Developers should not assume that all of the system tray * functionality is supported. To guarantee that the tray icon's * default action is always accessible, add the default action to * both the action listener and the popup menu. See the {@link * SystemTray example} for an example of how to do this. * *
Note: When implementing SystemTray and
* TrayIcon it is strongly recommended that
* you assign different gestures to the popup menu and an action
* event. Overloading a gesture for both purposes is confusing
* and may prevent the user from accessing one or the other.
*
* @see #getSystemTray
* @return false if no system tray access is supported; this
* method returns true if the minimal system tray access is
* supported but does not guarantee that all system tray
* functionality is supported for the current platform
*/
public static boolean isSupported() {
Toolkit toolkit = Toolkit.getDefaultToolkit();
if (toolkit instanceof SunToolkit) {
// connecting tray to native resource
initializeSystemTrayIfNeeded();
return ((SunToolkit)toolkit).isTraySupported();
} else if (toolkit instanceof HeadlessToolkit) {
// skip initialization as the init routine
// throws HeadlessException
return ((HeadlessToolkit)toolkit).isTraySupported();
} else {
return false;
}
}
/**
* Adds a TrayIcon to the SystemTray.
* The tray icon becomes visible in the system tray once it is
* added. The order in which icons are displayed in a tray is not
* specified - it is platform and implementation-dependent.
*
*
All icons added by the application are automatically
* removed from the All icons added by the application are automatically
* removed from the If The returned array is a copy of the actual array and may be
* modified in any way without affecting the system tray. To
* remove a
* If {@code listener} is {@code null}, no exception is thrown
* and no action is performed.
*
* @param propertyName the specified property
* @param listener the property change listener to be added
*
* @see #removePropertyChangeListener
* @see #getPropertyChangeListeners
*/
public synchronized void addPropertyChangeListener(String propertyName,
PropertyChangeListener listener)
{
if (listener == null) {
return;
}
getCurrentChangeSupport().addPropertyChangeListener(propertyName, listener);
}
/**
* Removes a {@code PropertyChangeListener} from the listener list
* for a specific property.
*
* The {@code PropertyChangeListener} must be from this context.
*
* If {@code propertyName} or {@code listener} is {@code null} or invalid,
* no exception is thrown and no action is taken.
*
* @param propertyName the specified property
* @param listener the PropertyChangeListener to be removed
*
* @see #addPropertyChangeListener
* @see #getPropertyChangeListeners
*/
public synchronized void removePropertyChangeListener(String propertyName,
PropertyChangeListener listener)
{
if (listener == null) {
return;
}
getCurrentChangeSupport().removePropertyChangeListener(propertyName, listener);
}
/**
* Returns an array of all the listeners that have been associated
* with the named property.
*
* Only the listeners in this context are returned.
*
* @param propertyName the specified property
* @return all of the {@code PropertyChangeListener}s associated with
* the named property; if no such listeners have been added or
* if {@code propertyName} is {@code null} or invalid, an empty
* array is returned
*
* @see #addPropertyChangeListener
* @see #removePropertyChangeListener
*/
public synchronized PropertyChangeListener[] getPropertyChangeListeners(String propertyName) {
return getCurrentChangeSupport().getPropertyChangeListeners(propertyName);
}
// ***************************************************************
// ***************************************************************
/**
* Support for reporting bound property changes for Object properties.
* This method can be called when a bound property has changed and it will
* send the appropriate PropertyChangeEvent to any registered
* PropertyChangeListeners.
*
* @param propertyName the property whose value has changed
* @param oldValue the property's previous value
* @param newValue the property's new value
*/
private void firePropertyChange(String propertyName,
Object oldValue, Object newValue)
{
if (oldValue != null && newValue != null && oldValue.equals(newValue)) {
return;
}
getCurrentChangeSupport().firePropertyChange(propertyName, oldValue, newValue);
}
/**
* Returns the current PropertyChangeSupport instance for the
* calling thread's context.
*
* @return this thread's context's PropertyChangeSupport
*/
private synchronized PropertyChangeSupport getCurrentChangeSupport() {
PropertyChangeSupport changeSupport =
(PropertyChangeSupport)AppContext.getAppContext().get(SystemTray.class);
if (changeSupport == null) {
changeSupport = new PropertyChangeSupport(this);
AppContext.getAppContext().put(SystemTray.class, changeSupport);
}
return changeSupport;
}
synchronized void addNotify() {
if (peer == null) {
Toolkit toolkit = Toolkit.getDefaultToolkit();
if (toolkit instanceof SunToolkit) {
peer = ((SunToolkit)Toolkit.getDefaultToolkit()).createSystemTray(this);
} else if (toolkit instanceof HeadlessToolkit) {
peer = ((HeadlessToolkit)Toolkit.getDefaultToolkit()).createSystemTray(this);
}
}
}
static void checkSystemTrayAllowed() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkPermission(SecurityConstants.AWT.ACCESS_SYSTEM_TRAY_PERMISSION);
}
}
private static void initializeSystemTrayIfNeeded() {
synchronized (SystemTray.class) {
if (systemTray == null) {
systemTray = new SystemTray();
}
}
}
}
SystemTray upon application exit
* and also when the desktop system tray becomes unavailable.
*
* @param trayIcon the TrayIcon to be added
* @throws NullPointerException if trayIcon is
* null
* @throws IllegalArgumentException if the same instance of
* a TrayIcon is added more than once
* @throws AWTException if the desktop system tray is missing
* @see #remove(TrayIcon)
* @see #getSystemTray
* @see TrayIcon
* @see java.awt.Image
*/
public void add(TrayIcon trayIcon) throws AWTException {
if (trayIcon == null) {
throw new NullPointerException("adding null TrayIcon");
}
TrayIcon[] oldArray = null, newArray = null;
VectorTrayIcon from the
* SystemTray.
*
* SystemTray upon application exit
* and also when the desktop system tray becomes unavailable.
*
* trayIcon is null or was not
* added to the system tray, no exception is thrown and no action
* is performed.
*
* @param trayIcon the TrayIcon to be removed
* @see #add(TrayIcon)
* @see TrayIcon
*/
public void remove(TrayIcon trayIcon) {
if (trayIcon == null) {
return;
}
TrayIcon[] oldArray = null, newArray = null;
synchronized (this) {
oldArray = systemTray.getTrayIcons();
VectorTrayIcon from the
* SystemTray, use the {@link
* #remove(TrayIcon)} method.
*
* @return an array of all tray icons added to this tray, or an
* empty array if none has been added
* @see #add(TrayIcon)
* @see TrayIcon
*/
public TrayIcon[] getTrayIcons() {
VectorTrayIcon class.
*
* @return the default size of a tray icon, in pixels
* @see TrayIcon#setImageAutoSize(boolean)
* @see java.awt.Image
* @see TrayIcon#getSize()
*/
public Dimension getTrayIconSize() {
return peer.getTrayIconSize();
}
/**
* Adds a {@code PropertyChangeListener} to the list of listeners for the
* specific property. The following properties are currently supported:
*
*
*
*
* Property
* Description
*
*
* {@code trayIcons}
* The {@code SystemTray}'s array of {@code TrayIcon} objects.
* The array is accessed via the {@link #getTrayIcons} method.
*
* This property is changed when a tray icon is added to (or removed
* from) the system tray.
For example, this property is changed
* when the system tray becomes unavailable on the desktop
* and the tray icons are automatically removed.
*
* {@code systemTray}
* This property contains {@code SystemTray} instance when the system tray
* is available or
* null otherwise.
This property is changed
* when the system tray becomes available or unavailable on the desktop.
* The property is accessed by the {@link #getSystemTray} method.