cat.albirar.framework.utilities.PageUtilities.java Source code

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Here is the source code for cat.albirar.framework.utilities.PageUtilities.java

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/*
 * This file is part of "core".
 * 
 * "core" is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
 * 
 * "core" is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License along with calendar. If not, see
 * <http://www.gnu.org/licenses/>.
 * 
 * Copyright (C) 2015 Octavi Forns <ofornes@albirar.cat>
 */

package cat.albirar.framework.utilities;

import org.springframework.data.domain.PageRequest;
import org.springframework.data.domain.Pageable;

/**
 * Utilities for {@link Pageable}.
 * 
 * @author <a href="mailto:ofornes@albirar.cat">Octavi Forns ofornes@albirar.cat</a>
 * @since 1.0
 */
public abstract class PageUtilities {
    /** Default page size. */
    public static final int PAGE_SIZE = 25;

    /**
     * Clone a {@link Pageable} object.
     * 
     * @param origin The origin
     * @return The new instance with all the origin values. Null if origin is null
     */
    public static final Pageable copyPageable(Pageable origin) {
        Pageable d;

        if (origin != null) {
            d = new PageRequest(origin.getPageNumber(), origin.getPageSize(), origin.getSort());
        } else {
            d = null;
        }
        return d;
    }

    /**
     * Clone or instantiate a {@link Pageable}.
     * 
     * @param origin The origin. If null, a new instance with page one and {@value #PAGE_SIZE} items for page is
     *            created.
     * @return The cloned object or a new instance with default values if origin is null
     */
    public static final Pageable copyOrCreatePageable(Pageable origin) {
        Pageable d;

        if (origin != null) {
            d = copyPageable(origin);
        } else {
            d = new PageRequest(0, PAGE_SIZE);
        }
        return d;
    }

    /**
     * Check (and adjust) the values of a {@link Pageable} object. Check that:
     * <ul>
     * <li>{@link Pageable#getPageSize() origin.getPageSize()} is equals or great than one</li>
     * <li>{@link Pageable#getPageNumber() origin.getPageNumber()} is equals or great than zero</li>
     * </ul>
     * <strong>WARNING!!</strong> {@link Pageable} is immutable, so you should to use the same returned object
     * 
     * @param origin The origin
     * @return A new instance, amended if needed. Null in case that origin is null
     */
    public static final Pageable checkAndAdjust(Pageable origin) {
        int elements, pagina;

        if (origin != null) {
            if (origin.getPageSize() < 1) {
                elements = PAGE_SIZE;
            } else {
                elements = origin.getPageSize();
            }

            if (origin.getPageNumber() < 0) {
                pagina = 0;
            } else {
                pagina = origin.getPageNumber();
            }
            return new PageRequest(pagina, elements);
        }
        return null;
    }
}