listdispatcher.java

dspace 用j2ee架构的一个数字图书馆.开源程序

/*
 * Copyright (c) 2004-2005, Hewlett-Packard Company and Massachusetts
 * Institute of Technology.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *
 * - Neither the name of the Hewlett-Packard Company nor the name of the
 * Massachusetts Institute of Technology nor the names of their
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS 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 COPYRIGHT
 * HOLDERS OR 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
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 * 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.
 */
package org.dspace.checker;

import java.util.Collections;
import java.util.EmptyStackException;
import java.util.List;
import java.util.Stack;

/**
 * Really simple dispatcher that just iterates over a pre-defined list of ids.
 * 
 * @author Jim Downing
 * @author Grace Carpenter
 * @author Nathan Sarr
 * 
 */
public class ListDispatcher implements BitstreamDispatcher
{
    /**
     * List of Integer ids.
     */
    Stack bitstreams = new Stack();

    /**
     * Blanked off, no-op constructor. Do not use.
     */
    private ListDispatcher()
    {
        ;
    }

    /**
     * Main constructor.
     * 
     * @param bitstreamIds
     *            List of Integer ids to dispatch.
     */
    public ListDispatcher(List bitstreamIds)
    {
        Collections.reverse(bitstreamIds);
        bitstreams.addAll(bitstreamIds);
    }

    /**
     * @see org.dspace.checker.BitstreamDispatcher#next()
     */
    public synchronized int next()
    {
        try
        {
            return ((Integer) bitstreams.pop()).intValue();
        }
        catch (EmptyStackException e)
        {
            return SENTINEL;
        }
    }
}