Package com.norconex.commons.lang.event

Class EventManager

java.lang.Object
com.norconex.commons.lang.event.EventManager
public class EventManager extends Object

Manages event listeners and logs events. New event managers can be constructed with a "parent" event manager. When chained as such, event on a particular event manager are bubbled up to the parents but never down to children. Events are logged by the manager in the chain that first fires the event.

When an event holds an exception, a summarized version of it is logged by default. To have the full stack trace logged by this event manager, set the log level for the corresponding class to `DEBUG` (or more verbose).

Since:
2.0.0

  • Constructor Details

    • EventManager

      public EventManager()

    • EventManager

      public EventManager(EventManager parentEventManager)
      Wraps a parent event manager. Events fired on this event manager will be fired on this instance listeners first, then its parent listeners. Modifying the list of listeners in this instance does not impact listeners of the parent event manager.
      Parameters:
      parentEventManager - parent event manager

  • Method Details

    • addListener

      public void addListener(EventListener<Event> listener)
      Adds an event listener. Event listeners are added by "identity", meaning you can have multiple listeners coexisting even if their test for equality returns true. Adding a null event listener has no effect.
      Parameters:
      listener - an event listener

    • addListeners

      public void addListeners(Collection<EventListener<Event>> listeners)
      Adds event listeners. Event listeners are added by "identity", meaning you can have multiple listeners coexisting even if their test for equality returns true. Adding a null collection has no effect.
      Parameters:
      listeners - event listeners

    • addListenersFromScan

      public void addListenersFromScan(Object obj)
      Adds listeners found in an object graph. Recursively queries the object bean properties for non null objects implementing EventListener.
      Parameters:
      obj - the object to retrive listeners from

    • getListeners

      public List<EventListener<Event>> getListeners()
      Returns an unmodifiable list of event listeners in this event manager.
      Returns:
      list of listeners

    • removeListener

      public boolean removeListener(EventListener<Event> listener)
      Removes a listener instance. Removal is done by "identity", meaning you can have listeners that are not removed despite testing true for equality. Removing a null listener has no effect.
      Parameters:
      listener - the listener instance to remove
      Returns:
      true if a matching instance was removed

    • removeListeners

      public boolean removeListeners(Collection<EventListener<Event>> listeners)
      Removes listener instances. Removal is done by "identity", meaning you can have listeners that are not removed despite testing true for equality. Removing a null collection has no effect.
      Parameters:
      listeners - listener instances to remove
      Returns:
      true if one or more listeners were removed

    • clearListeners

      public void clearListeners()
      Clears all previously added listeners. Does not affect listeners associated with a parent event manager.

    • getListenerCount

      public int getListenerCount()
      Gets the number of event listeners registered with this event manager. Listeners attached to a parent are not counted.
      Returns:
      listener count

    • fire

      public void fire(Event event)

    • fire

      public void fire(Event event, Level level)

    • bindParent

      public void bindParent(EventManager parentEventManager)

    • log

      public void log(Event event, Level level)