Module java.naming
Package javax.naming.event

Class NamingEvent

  • All Implemented Interfaces:
    Serializable
    public class NamingEvent
extends EventObject
    This class represents an event fired by a naming/directory service.

    The NamingEvent's state consists of

    • The event source: the EventContext which fired this event.
    • The event type.
    • The new binding: information about the object after the change.
    • The old binding: information about the object before the change.
    • Change information: information about the change that triggered this event; usually service provider-specific or server-specific information.

    Note that the event source is always the same EventContext instance that the listener has registered with. Furthermore, the names of the bindings in the NamingEvent are always relative to that instance. For example, suppose a listener makes the following registration: 

         NamespaceChangeListener listener = ...;
     src.addNamingListener("x", SUBTREE_SCOPE, listener);
    When an object named "x/y" is subsequently deleted, the corresponding NamingEvent (evt) must contain: 
         evt.getEventContext() == src
     evt.getOldBinding().getName().equals("x/y")
    Care must be taken when multiple threads are accessing the same EventContext concurrently. See the package description for more information on threading issues.

    Since:
    1.3
    See Also:
    NamingListener, EventContext, Serialized Form

    • Field Detail

      • OBJECT_ADDED

        public static final int OBJECT_ADDED
        Naming event type for indicating that a new object has been added. The value of this constant is 0.
        See Also:
        Constant Field Values

      • OBJECT_REMOVED

        public static final int OBJECT_REMOVED
        Naming event type for indicating that an object has been removed. The value of this constant is 1.
        See Also:
        Constant Field Values

      • OBJECT_RENAMED

        public static final int OBJECT_RENAMED
        Naming event type for indicating that an object has been renamed. Note that some services might fire multiple events for a single logical rename operation. For example, the rename operation might be implemented by adding a binding with the new name and removing the old binding.

        The old/new binding in NamingEvent may be null if the old name or new name is outside of the scope for which the listener has registered.

        When an interior node in the namespace tree has been renamed, the topmost node which is part of the listener's scope should used to generate a rename event. The extent to which this can be supported is provider-specific. For example, a service might generate rename notifications for all descendants of the changed interior node and the corresponding provider might not be able to prevent those notifications from being propagated to the listeners.

        The value of this constant is 2.

        See Also:
        Constant Field Values

      • OBJECT_CHANGED

        public static final int OBJECT_CHANGED
        Naming event type for indicating that an object has been changed. The changes might include the object's attributes, or the object itself. Note that some services might fire multiple events for a single modification. For example, the modification might be implemented by first removing the old binding and adding a new binding containing the same name but a different object.

        The value of this constant is 3.

        See Also:
        Constant Field Values

      • changeInfo

        protected Object changeInfo
        Contains information about the change that generated this event.

      • oldBinding

        protected Binding oldBinding
        Contains information about the object before the change.

      • newBinding

        protected Binding newBinding
        Contains information about the object after the change.

    • Constructor Detail

      • NamingEvent

        public NamingEvent​(EventContext source,
                   int type,
                   Binding newBd,
                   Binding oldBd,
                   Object changeInfo)
        Constructs an instance of NamingEvent.

        The names in newBd and oldBd are to be resolved relative to the event source source. For an OBJECT_ADDED event type, newBd must not be null. For an OBJECT_REMOVED event type, oldBd must not be null. For an OBJECT_CHANGED event type, newBd and oldBd must not be null. For an OBJECT_RENAMED event type, one of newBd or oldBd may be null if the new or old binding is outside of the scope for which the listener has registered.

        Parameters:
        source - The non-null context that fired this event.
        type - The type of the event.
        newBd - A possibly null binding before the change. See method description.
        oldBd - A possibly null binding after the change. See method description.
        changeInfo - A possibly null object containing information about the change.
        See Also:
        OBJECT_ADDED, OBJECT_REMOVED, OBJECT_RENAMED, OBJECT_CHANGED

    • Method Detail

      • getEventContext

        public EventContext getEventContext()
        Retrieves the event source that fired this event. This returns the same object as EventObject.getSource().

        If the result of this method is used to access the event source, for example, to look up the object or get its attributes, then it needs to be locked because implementations of Context are not guaranteed to be thread-safe (and EventContext is a subinterface of Context). See the package description for more information on threading issues.

        Returns:
        The non-null context that fired this event.

      • getOldBinding

        public Binding getOldBinding()
        Retrieves the binding of the object before the change.

        The binding must be nonnull if the object existed before the change relative to the source context (getEventContext()). That is, it must be nonnull for OBJECT_REMOVED and OBJECT_CHANGED. For OBJECT_RENAMED, it is null if the object before the rename is outside of the scope for which the listener has registered interest; it is nonnull if the object is inside the scope before the rename.

        The name in the binding is to be resolved relative to the event source getEventContext(). The object returned by Binding.getObject() may be null if such information is unavailable.

        Returns:
        The possibly null binding of the object before the change.

      • getNewBinding

        public Binding getNewBinding()
        Retrieves the binding of the object after the change.

        The binding must be nonnull if the object existed after the change relative to the source context (getEventContext()). That is, it must be nonnull for OBJECT_ADDED and OBJECT_CHANGED. For OBJECT_RENAMED, it is null if the object after the rename is outside the scope for which the listener registered interest; it is nonnull if the object is inside the scope after the rename.

        The name in the binding is to be resolved relative to the event source getEventContext(). The object returned by Binding.getObject() may be null if such information is unavailable.

        Returns:
        The possibly null binding of the object after the change.

      • getChangeInfo

        public Object getChangeInfo()
        Retrieves the change information for this event. The value of the change information is service-specific. For example, it could be an ID that identifies the change in a change log on the server.
        Returns:
        The possibly null change information of this event.

      • dispatch

        public void dispatch​(NamingListener listener)
        Invokes the appropriate listener method on this event. The default implementation of this method handles the following event types: OBJECT_ADDED, OBJECT_REMOVED, OBJECT_RENAMED, OBJECT_CHANGED.

        The listener method is executed in the same thread as this method. See the package description for more information on threading issues.

        Parameters:
        listener - The nonnull listener.