com.trenako.results.RollingStockResults.java Source code

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Here is the source code for com.trenako.results.RollingStockResults.java

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/*
 * Copyright 2012 the original author or authors.
 * 
 * Licensed 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 com.trenako.results;

import java.util.List;

import org.apache.commons.beanutils.BeanUtilsBean;
import org.apache.commons.beanutils.PropertyUtilsBean;

import com.trenako.criteria.SearchCriteria;
import com.trenako.entities.RollingStock;

/**
 * The concrete implementation for MongoDB of the {@code PaginatedResults}.
 * <p>
 * It is expected the actual result list size will be
 * {@code RollingStockResults#getPageSize() + 1}; the existence of this element
 * (not shown in the final result) will be used to ensure whether the current
 * result set is the last page or not.
 * </p>
 * <p>
 * Although the objects for this class contain the fields
 * {@code RollingStockResults#getSinceId()} and {@code RollingStockResults#getMaxId()}
 * they don't contain the values from the {@code RangeRequest} instance used to build the
 * object. They are filled with the first and the last element in the results set.
 * The clients should use these two fields to implement the pagination.
 * </p>
 * <p>
 * This implementation of {@code PaginatedResults} doesn't provide a meaningful
 * implementation for the {@code PaginatedResults#getTotalSize()} method.
 * The client classes must not depend on this value.
 * </p>
 *
 * @author Carlo Micieli
 */
public class RollingStockResults implements PaginatedResults<RollingStock> {

    private final List<RollingStock> results;
    private final SearchRange range;
    private final SearchCriteria criteria;

    private final boolean hasNext;
    private final boolean hasPrevious;

    /**
     * Creates a new {@code RollingStockResults}.
     *
     * @param results the result items
     * @param range   the result range
     */
    public RollingStockResults(List<RollingStock> results, SearchCriteria criteria, RangeRequest range) {

        int size = results.size() > range.getSize() ? range.getSize() : results.size();

        this.results = results.subList(0, size);
        this.criteria = criteria;

        if (!isEmpty()) {
            final RollingStock minRs = results.get(0);
            final RollingStock maxRs = results.get(size - 1);

            Object since, max;
            if (range.getDirection().equals("desc")) {
                since = safeGetProperty(maxRs, range.getSortProperty());
                max = safeGetProperty(minRs, range.getSortProperty());
            } else {
                since = safeGetProperty(minRs, range.getSortProperty());
                max = safeGetProperty(maxRs, range.getSortProperty());
            }

            this.hasPrevious = range.getSince() != null;
            this.hasNext = results.size() > range.getSize();

            this.range = new SearchRange(range.getSize(), range.getSort(), since, max);
        } else {
            this.range = null;
            this.hasPrevious = false;
            this.hasNext = false;
        }
    }

    @Override
    public boolean hasPreviousPage() {
        return hasPrevious;
    }

    @Override
    public boolean hasNextPage() {
        return hasNext;
    }

    @Override
    public Iterable<RollingStock> getItems() {
        return results;
    }

    @Override
    public SearchCriteria getCriteria() {
        return criteria;
    }

    @Override
    public SearchRange getRange() {
        return range;
    }

    @Override
    public boolean isEmpty() {
        return (results == null || results.size() == 0);
    }

    protected Object safeGetProperty(Object bean, String name) {
        try {
            PropertyUtilsBean pb = BeanUtilsBean.getInstance().getPropertyUtils();
            return pb.getProperty(bean, name);
        } catch (Exception e) {
            return null;
        }
    }
}