commandfactory.java

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/*
*  Copyright (c) 2001 Sun Microsystems, Inc.  All rights
*  reserved.
*
*  Redistribution and use in source and binary forms, with or without
*  modification, are permitted provided that the following conditions
*  are met:
*
*  1. Redistributions of source code must retain the above copyright
*  notice, this list of conditions and the following disclaimer.
*
*  2. Redistributions in binary form must reproduce the above copyright
*  notice, this list of conditions and the following discalimer in
*  the documentation and/or other materials provided with the
*  distribution.
*
*  3. The end-user documentation included with the redistribution,
*  if any, must include the following acknowledgment:
*  "This product includes software developed by the
*  Sun Microsystems, Inc. for Project JXTA."
*  Alternately, this acknowledgment may appear in the software itself,
*  if and wherever such third-party acknowledgments normally appear.
*
*  4. The names "Sun", "Sun Microsystems, Inc.", "JXTA" and "Project JXTA"
*  must not be used to endorse or promote products derived from this
*  software without prior written permission. For written
*  permission, please contact Project JXTA at http://www.jxta.org.
*
*  5. Products derived from this software may not be called "JXTA",
*  nor may "JXTA" appear in their name, without prior written
*  permission of Sun.
*
*  THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
*  WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
*  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
*  DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
*  ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
*  SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
*  LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
*  USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
*  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
*  OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
*  OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
*  SUCH DAMAGE.
*  ====================================================================
*
*  This software consists of voluntary contributions made by many
*  individuals on behalf of Project JXTA.  For more
*  information on Project JXTA, please see
*  <http://www.jxta.org/>.
*
*  This license is based on the BSD license adopted by the Apache Foundation.
*
*  $Id: CommandFactory.java,v 1.16 2006/07/06 19:15:21 nano Exp $
*/

package net.jxta.myjxta.dialog;

import net.jxta.myjxta.dialog.commands.PingCommand;
import net.jxta.myjxta.dialog.commands.ProfileCommand;
import net.jxta.myjxta.dialog.commands.StatusCommand;

import java.lang.reflect.Field;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

/**
 * @author james todd [gonzo at jxta dot org]
 * @version $Id: CommandFactory.java,v 1.16 2006/07/06 19:15:21 nano Exp $
 */

public final class CommandFactory {

    private static final String ID = "ID";
    private static final String REQUEST_PREAMBLE = "request id=\"";
    private static final String REQUEST_POSTAMBLE = "\"";
    private static final String RESPONSE_PREAMBLE = "<response";

    private static final List<Class> commands = new ArrayList<Class>();

    static {
        //todo plugins: this has to be done inside the plugins themselve
        commands.add(StatusCommand.class);
        commands.add(PingCommand.class);
        commands.add(ProfileCommand.class);
    }

    public static void registerCommand(Class commandClass) {
        commands.add(commandClass);
    }

    public static void unregisterCommand(Class commandClass) {
        commands.remove(commandClass);
    }

    public static Command getCommand(String id) {
        Command c = null;
        String cs = getCommandId(id);

        if (cs != null &&
                cs.length() > 0) {
            Class cl = null;
            String s = null;

            for (Iterator<Class> ci = commands.iterator();
                 ci.hasNext() && c == null;) {
                cl = ci.next();

                try {
                    Field f = cl.getField(ID); //nano: thats a joke isnt it?

                    s = f != null ? (String) f.get(null) : null;
                } catch (NoSuchFieldException nsfe) {
                    nsfe.printStackTrace();
                } catch (IllegalAccessException iae) {
                    iae.printStackTrace();
                }

                if (s != null &&
                        s.trim().equals(cs)) {
                    try {
                        c = (Command) cl.newInstance();
                    } catch (InstantiationException ia) {
                        ia.printStackTrace();
                    } catch (IllegalAccessException iae) {
                        iae.printStackTrace();
                    }
                }
            }
        }

        return c;
    }

    private static String getCommandId(String s) {
        String id = null;

        s = s != null ? s.trim() : null;

        if (s != null) {
            int i = s.indexOf(REQUEST_PREAMBLE);
            int j = s.indexOf(REQUEST_POSTAMBLE, i + REQUEST_PREAMBLE.length());
            int k = s.indexOf(RESPONSE_PREAMBLE);

            if (i > -1 &&
                    j > i &&
                    k == -1) {
                id = s.substring(i + REQUEST_PREAMBLE.length(), j);
            }
        }

        return id;
    }
}