multicastcallerlistener.java

OpenJMS是一个开源的Java Message Service API 1.0.2 规范的实现,它包含有以下特性： *. 它既支持点到点（point-to-point）（PTP）模型和发布/订

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 *
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 * Copyright 2000-2004 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: MulticastCallerListener.java,v 1.2 2005/05/27 13:58:00 tanderson Exp $
 */
package org.exolab.jms.net.connector;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.exolab.jms.net.uri.InvalidURIException;
import org.exolab.jms.net.uri.URI;
import org.exolab.jms.net.uri.URIHelper;


/**
 * A listener for {@link Caller} events, which asynchronously propagates events
 * to one or more registered listeners.
 *
 * @author <a href="mailto:[e-mail]">Tim Anderson</a>
 * @version $Revision: 1.2 $ $Date: 2005/05/27 13:58:00 $
 */
public class MulticastCallerListener implements CallerListener {

    /**
     * The listeners. A set of <code>List</code> instances, keyed on
     * URI.
     */
    private Map _listeners = Collections.synchronizedMap(new HashMap());

    /**
     * Helper for casts.
     */
    private static final CallerListener[] EMPTY = new CallerListener[0];


    /**
     * Registers an event listener for caller events.
     *
     * @param uri      the remote URI to listen for events on
     * @param listener the event listener
     * @throws InvalidURIException if <code>uri</code> is invalid
     */
    public void addCallerListener(String uri, CallerListener listener)
        throws InvalidURIException{
        URI parsed = URIHelper.parse(uri);
        parsed = URIHelper.convertHostToAddress(parsed);
        List list = null;
        synchronized (_listeners) {
            list = (List) _listeners.get(parsed);
            if (list == null) {
                list = Collections.synchronizedList(new ArrayList());
                _listeners.put(parsed, list);
            }
        }
        list.add(listener);
    }

    /**
     * Removes an event listener for caller events.
     *
     * @param uri      the remote URI to remove the listener for
     * @param listener the event listener to remove
     * @throws InvalidURIException if <code>uri</code> is invalid
     */
    public void removeCallerListener(String uri, CallerListener listener)
        throws InvalidURIException {
        URI parsed = URIHelper.parse(uri);
        parsed = URIHelper.convertHostToAddress(parsed);
        List list = null;
        synchronized (_listeners) {
            list = (List) _listeners.get(parsed);
            if (list != null) {
                list.remove(listener);
            }
        }
    }

    /**
     * Notifies that a connection has been disconnected.
     *
     * @param caller the caller that was disconnected
     */
    public void disconnected(Caller caller) {
        CallerListener[] listeners = getListeners(caller.getRemoteURI());
        for (int i = 0; i < listeners.length; ++i) {
            listeners[i].disconnected(caller);
        }
    }

    /**
     * Returns the registered listeners for a given URI.
     *
     * @param uri the URI to return the registered listsners for
     * @return the registered listeners
     */
    private CallerListener[] getListeners(URI uri) {
        CallerListener[] result = EMPTY;
        List list = null;
        synchronized (_listeners) {
            list = (List) _listeners.get(uri);
            if (list == null) {
                list = (List) _listeners.get(uri);
            }
        }
        if (list != null) {
            result = (CallerListener[]) list.toArray(EMPTY);
        }
        return result;
    }
}