menuitem.java

《移动Agent技术》一书的所有章节源代码。

        }						/*ibm.3202*/
    }

    /**
     * Delete any <code>MenuShortcut</code> object associated
     * with this menu item.
     * @since      JDK1.1
     */
    public void deleteShortcut() {
        shortcut = null;
        synchronized (getTreeLock()) {			/*ibm.3202*/
	    MenuItemPeer peer = (MenuItemPeer)this.peer;
	    if (peer != null) {
	        peer.setLabel(label);
	    }
        }						/*ibm.3202*/
    }

    /*
     * Delete a matching MenuShortcut associated with this MenuItem.
     * Used when iterating Menus.
     */
    void deleteShortcut(MenuShortcut s) {
        synchronized (getTreeLock()) {			/*ibm.3202*/
            if (s.equals(shortcut)) {
                shortcut = null;
                MenuItemPeer peer = (MenuItemPeer)this.peer;
                if (peer != null) {
                    peer.setLabel(label);
                }
            }
        }						/*ibm.3202*/
    }

    /*
     * Post an ActionEvent to the target (on
     * keydown).  Returns true if there is an associated
     * shortcut.
     */
    boolean handleShortcut(KeyEvent e) {
        MenuShortcut s = new MenuShortcut(e.getKeyCode(),
                             (e.getModifiers() & InputEvent.SHIFT_MASK) > 0);
        if (s.equals(shortcut) && enabled) {
            // MenuShortcut match -- issue an event on keydown.
            if (e.getID() == KeyEvent.KEY_PRESSED) {
                Toolkit.getEventQueue().postEvent(
                          new ActionEvent(this, ActionEvent.ACTION_PERFORMED,
                                          actionCommand));
            } else {
                // silently eat key release.
            }
            return true;
	}
        return false;
    }

    MenuItem getShortcutMenuItem(MenuShortcut s) {
        return (s.equals(shortcut)) ? this : null;
    }

    /**
     * Enables event delivery to this menu item for events
     * to be defined by the specified event mask parameter
     * <p>
     * Since event types are automatically enabled when a listener for
     * that type is added to the menu item, this method only needs
     * to be invoked by subclasses of <code>MenuItem</code> which desire to
     * have the specified event types delivered to <code>processEvent</code>
     * regardless of whether a listener is registered.
     * @param       eventsToEnable the event mask defining the event types.
     * @see         java.awt.MenuItem#processEvent
     * @see         java.awt.MenuItem#disableEvents
     * @see         java.awt.Component#enableEvents
     * @since       JDK1.1
     */
    protected final void enableEvents(long eventsToEnable) {
        eventMask |= eventsToEnable;
    }

    /**
     * Disables event delivery to this menu item for events
     * defined by the specified event mask parameter.
     * @param       eventsToDisable the event mask defining the event types.
     * @see         java.awt.MenuItem#processEvent
     * @see         java.awt.MenuItem#enableEvents
     * @see         java.awt.Component#disableEvents
     * @since       JDK1.1
     */
    protected final void disableEvents(long eventsToDisable) {
        eventMask &= ~eventsToDisable;
    }

    /**
     * Sets the command name of the action event that is fired
     * by this menu item.
     * <p>
     * By default, the action command is set to the label of
     * the menu item.
     * @param       command   the action command to be set
     *                                for this menu item.
     * @see         java.awt.MenuItem#getActionCommand
     * @since       JDK1.1
     */
    public void setActionCommand(String command) {
        actionCommand = command;
    }

    /**
     * Gets the command name of the action event that is fired
     * by this menu item.
     * @see         java.awt.MenuItem#setActionCommand
     * @since       JDK1.1
     */
    public String getActionCommand() {
        return (actionCommand == null? label : actionCommand);
    }

    /**
     * Adds the specified action listener to receive action events
     * from this menu item.
     * @param      l the action listener.
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.event.ActionListener
     * @see        java.awt.MenuItem#removeActionListener
     * @since      JDK1.1
     */
    public synchronized void addActionListener(ActionListener l) {
	actionListener = AWTEventMulticaster.add(actionListener, l);
        newEventsOnly = true;
    }

    /**
     * Removes the specified action listener so it no longer receives
     * action events from this menu item.
     * @param      l the action listener.
     * @see        java.awt.event.ActionEvent
     * @see        java.awt.event.ActionListener
     * @see        java.awt.MenuItem#addActionListener
     * @since      JDK1.1
     */
    public synchronized void removeActionListener(ActionListener l) {
	actionListener = AWTEventMulticaster.remove(actionListener, l);
    }

    /**
     * Processes events on this menu item. If the event is an
     * instance of <code>ActionEvent</code>, it invokes
     * <code>processActionEvent</code>, another method
     * defined by <code>MenuItem</code>.
     * <p>
     * Currently, menu items only support action events.
     * @param       e the event.
     * @see         java.awt.MenuItem#processActionEvent
     * @since       JDK1.1
     */
    protected void processEvent(AWTEvent e) {
        if (e instanceof ActionEvent) {
            processActionEvent((ActionEvent)e);
        }
    }

    // REMIND: remove when filtering is done at lower level
    boolean eventEnabled(AWTEvent e) {
        if (e.id == ActionEvent.ACTION_PERFORMED) {
            if ((eventMask & AWTEvent.ACTION_EVENT_MASK) != 0 ||
                actionListener != null) {
                return true;
            }
            return false;
        }
        return super.eventEnabled(e);
    }

    /**
     * Processes action events occurring on this menu item,
     * by dispatching them to any registered
     * <code>ActionListener</code> objects.
     * This method is not called unless action events are
     * enabled for this component. Action events are enabled
     * when one of the following occurs:
     * <p><ul>
     * <li>An <code>ActionListener</code> object is registered
     * via <code>addActionListener</code>.
     * <li>Action events are enabled via <code>enableEvents</code>.
     * </ul>
     * @param       e the action event.
     * @see         java.awt.event.ActionEvent
     * @see         java.awt.event.ActionListener
     * @see         java.awt.MenuItem#enableEvents
     * @since       JDK1.1
     */
    protected void processActionEvent(ActionEvent e) {
        if (actionListener != null) {
            actionListener.actionPerformed(e);
        }
    }

    /**
     * Returns the parameter string representing the state of this menu
     * item. This string is useful for debugging.
     * @return  the parameter string of this menu item.
     * @since   JDK1.0
     */
    public String paramString() {
        String str = ",label=" + label;
        if (shortcut != null) {
            str += ",shortcut=" + shortcut;
        }
        return super.paramString() + str;
    }


    /* Serialization support.
     */

    private int menuItemSerializedDataVersion = 1;


    private void writeObject(ObjectOutputStream s)
      throws IOException
    {
      s.defaultWriteObject();

      AWTEventMulticaster.save(s, actionListenerK, actionListener);
      s.writeObject(null);
    }


    private void readObject(ObjectInputStream s)
      throws ClassNotFoundException, IOException
    {
      s.defaultReadObject();

      Object keyOrNull;
      while(null != (keyOrNull = s.readObject())) {
	String key = ((String)keyOrNull).intern();

	if (actionListenerK == key)
	  addActionListener((ActionListener)(s.readObject()));

	else // skip value for unrecognized key
	  s.readObject();
      }
    }

}