ProtocolCommandSupport.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.commons.net;

import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.util.EventListener;

import org.apache.commons.net.util.ListenerList;

/**
 * ProtocolCommandSupport is a convenience class for managing a list of ProtocolCommandListeners and firing ProtocolCommandEvents. You can simply delegate
 * ProtocolCommandEvent firing and listener registering/unregistering tasks to this class.
 *
 *
 * @see ProtocolCommandEvent
 * @see ProtocolCommandListener
 */

public class ProtocolCommandSupport implements Serializable {
    private static final long serialVersionUID = -8017692739988399978L;

    private final Object source;
    private final ListenerList listeners;

    /**
     * Creates a ProtocolCommandSupport instance using the indicated source as the source of ProtocolCommandEvents.
     *
     * @param source The source to use for all generated ProtocolCommandEvents.
     */
    public ProtocolCommandSupport(final Object source) {
        this.listeners = new ListenerList();
        this.source = source;
    }

    /**
     * Adds a ProtocolCommandListener.
     *
     * @param listener The ProtocolCommandListener to add.
     */
    public void addProtocolCommandListener(final ProtocolCommandListener listener) {
        listeners.addListener(listener);
    }

    /**
     * Fires a ProtocolCommandEvent signalling the sending of a command to all registered listeners, invoking their
     * {@link org.apache.commons.net.ProtocolCommandListener#protocolCommandSent protocolCommandSent() } methods.
     *
     * @param command The string representation of the command type sent, not including the arguments (e.g., "STAT" or "GET").
     * @param message The entire command string verbatim as sent to the server, including all arguments.
     */
    public void fireCommandSent(final String command, final String message) {
        final ProtocolCommandEvent event;

        event = new ProtocolCommandEvent(source, command, message);

        for (final EventListener listener : listeners) {
            ((ProtocolCommandListener) listener).protocolCommandSent(event);
        }
    }

    /**
     * Fires a ProtocolCommandEvent signalling the reception of a command reply to all registered listeners, invoking their
     * {@link org.apache.commons.net.ProtocolCommandListener#protocolReplyReceived protocolReplyReceived() } methods.
     *
     * @param replyCode The integer code indicating the natureof the reply. This will be the protocol integer value for protocols that use integer reply codes,
     *                  or the reply class constant corresponding to the reply for protocols like POP3 that use strings like OK rather than integer codes (i.e.,
     *                  POP3Repy.OK).
     * @param message   The entire reply as received from the server.
     */
    public void fireReplyReceived(final int replyCode, final String message) {
        final ProtocolCommandEvent event;
        event = new ProtocolCommandEvent(source, replyCode, message);

        for (final EventListener listener : listeners) {
            ((ProtocolCommandListener) listener).protocolReplyReceived(event);
        }
    }

    /**
     * Returns the number of ProtocolCommandListeners currently registered.
     *
     * @return The number of ProtocolCommandListeners currently registered.
     */
    public int getListenerCount() {
        return listeners.getListenerCount();
    }

    private void readObject(final ObjectInputStream in) {
        throw new UnsupportedOperationException("Serialization is not supported");
    }

    /*
     * Serialization is unnecessary for this class. Reject attempts to do so until such time as the Serializable attribute can be dropped.
     */

    /**
     * Removes a ProtocolCommandListener.
     *
     * @param listener The ProtocolCommandListener to remove.
     */
    public void removeProtocolCommandListener(final ProtocolCommandListener listener) {
        listeners.removeListener(listener);
    }

    private void writeObject(final ObjectOutputStream out) {
        throw new UnsupportedOperationException("Serialization is not supported");
    }

}