browseinfo.java

dspace 用j2ee架构的一个数字图书馆.开源程序

/*
 * BrowseInfo.java
 *
 * Version: $Revision: 1.9 $
 *
 * Date: $Date: 2005/04/20 14:23:12 $
 *
 * Copyright (c) 2002-2005, 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
 * 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.
 */
package org.dspace.browse;

import java.util.Collections;
import java.util.List;

import org.dspace.content.Item;

/**
 * The results of a Browse method call.
 * 
 * <p>
 * Results are a List of objects returned from the browse; each returned object
 * is either a String (for getAuthors()) or an {@link org.dspace.content.Item}
 * (for all the getItems.... methods). The list is readonly, and is guaranteed
 * to be non-null.
 * </p>
 * 
 * <p>
 * overallPosition is the position of the first element of results within the
 * Browse index. Positions begin with 0.
 * </p>
 * 
 * <p>
 * total is the number of objects in the index. Note that this is a snapshot,
 * which is only guaranteed to be correct at the time the browse method was
 * called.
 * </p>
 * 
 * <p>
 * offset is the position of the requested object within the results. This
 * position is also 0-based.
 * </p>
 */
public class BrowseInfo
{
    /**
     * The results of the browse.
     */
    private List results;

    /**
     * The position of the first element of results within the Browse index.
     * Positions begin with 0.
     */
    private int overallPosition;

    /**
     * The position of the requested object within the results. Offsets begin
     * with 0.
     */
    private int offset;

    /**
     * The total number of items in the browse index.
     */
    private int total;

    /**
     * True if this browse was cached.
     */
    private boolean cached;

    /**
     * Constructor
     * 
     * @param results
     *            A List of Browse results
     * @param overallPosition
     *            The position of the first returned item in the overall index
     * @param total
     *            The total number of items in the index
     * @param offset
     *            The position of the requested item in the set of results
     */
    public BrowseInfo(List results, int overallPosition, int total, int offset)
    {
        if (results == null)
        {
            throw new IllegalArgumentException("Null result list not allowed");
        }

        this.results = Collections.unmodifiableList(results);
        this.overallPosition = overallPosition;
        this.total = total;
        this.offset = offset;
    }

    /**
     * The results of the Browse. Each member of the list is either a String
     * (for the authors browse) or an {@link org.dspace.content.Item}(for the
     * other browses).
     * 
     * @return Result list. This list cannot be modified.
     */
    public List getResults()
    {
        return results;
    }

    /**
     * Return the results of the Browse as a String array.
     * 
     * @return The results of the Browse as a String array.
     */
    public String[] getStringResults()
    {
        return (String[]) results.toArray(new String[results.size()]);
    }

    /**
     * Return the results of the Browse as an Item array.
     * 
     * @return The results of the Browse as an Item array.
     */
    public Item[] getItemResults()
    {
        return (Item[]) results.toArray(new Item[results.size()]);
    }

    /**
     * Return the number of results.
     * 
     * @return The number of results.
     */
    public int getResultCount()
    {
        return results.size();
    }

    /**
     * Return the position of the results in index being browsed. This is 0 for
     * the start of the index.
     * 
     * @return The position of the results in index being browsed.
     */
    public int getOverallPosition()
    {
        return overallPosition;
    }

    /**
     * Return the total number of items in the index.
     * 
     * @return The total number of items in the index.
     */
    public int getTotal()
    {
        return total;
    }

    /**
     * Return the position of the requested item or value in the set of results.
     * 
     * @return The position of the requested item or value in the set of results
     */
    public int getOffset()
    {
        return offset;
    }

    /**
     * True if there are no previous results from the browse.
     * 
     * @return True if there are no previous results from the browse
     */
    public boolean isFirst()
    {
        return overallPosition == 0;
    }

    /**
     * True if these are the last results from the browse.
     * 
     * @return True if these are the last results from the browse
     */
    public boolean isLast()
    {
        return (overallPosition + getResultCount()) == total;
    }

    /**
     * True if this browse was cached.
     */
    public boolean wasCached()
    {
        return cached;
    }

    /**
     * Set whether this browse was cached.
     */
    void setCached(boolean cached)
    {
        this.cached = cached;
    }
}