javax.faces.event.SystemEvent Maven / Gradle / Ivy

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package javax.faces.event;

import java.util.EventObject;
import javax.faces.context.FacesContext;

/**
 * SystemEvent 
 * is the base class for non-application specific events that can be fired by
 * arbitrary objects.
 *
 * @since 2.0
 */
public abstract class SystemEvent extends EventObject {

    private static final long serialVersionUID = 2696415667461888462L;

    /**
     * Stores the Faces context.
     */
    private transient FacesContext facesContext;

    // ------------------------------------------------------------ Constructors


    /**
     * Pass the argument
     * source to the superclass constructor.

     * @param source the source reference to be
     * passed to the superclass constructor.
     *
     * @throws IllegalArgumentException if the argument is
     * null.
     */
    public SystemEvent(Object source) {
        super(source);
    }

    /**
     * Pass the argument
     * source to the superclass constructor.
     * 
     * @param facesContext the Faces context.
     * @param source the source reference to be
     * passed to the superclass constructor.
     *
     * @throws IllegalArgumentException if the argument is
     * null.
     */
    public SystemEvent(FacesContext facesContext, Object source) {
        super(source);
        this.facesContext = facesContext;
    }

    // ---------------------------------------------------------- Public Methods

    /**
     * Get the Faces context.
     * 
     * 
     *  If the constructor was passed a FacesContext we return it, otherwise
     *  we call FacesContext.getCurrentInstance() and return it.
     * 
     * 
     * @return the Faces context.
     * @since 2.3
     */
    public FacesContext getFacesContext() {
        if (facesContext == null) {
            facesContext = FacesContext.getCurrentInstance();
        }
        return facesContext;
    }

    /**
     * Return true 
     * if this {@link FacesListener} is an
     * instance of a the appropriate listener class that this event
     * supports. The default implementation returns true if the listener
     * is a {@link ComponentSystemEventListener}.
     *
     * @param listener {@link FacesListener} to evaluate
     * 
     * @return the result as specified above
     */
    public boolean isAppropriateListener(FacesListener listener) {

        return (listener instanceof SystemEventListener);

    }


    /**
     * Broadcast this event instance to the specified
     * {@link FacesListener}, by whatever mechanism is appropriate.  Typically,
     * this will be accomplished by calling an event processing method, and
     * passing this instance as a parameter.
     *
     * @param listener {@link FacesListener} to send this {@link FacesEvent} to
     *
     * @throws AbortProcessingException Signal the JavaServer Faces
     *  implementation that no further processing on the current event
     *  should be performed
     */
    public void processListener(FacesListener listener) {

        ((SystemEventListener) listener).processEvent(this);

    }
}