processrowscallback.java

exTreme taglib的使用

/*
 * Copyright 2004 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 org.extremecomponents.table.callback;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.List;

import org.apache.commons.beanutils.BeanComparator;
import org.apache.commons.collections.CollectionUtils;
import org.apache.commons.collections.comparators.NullComparator;
import org.apache.commons.collections.comparators.ReverseComparator;
import org.extremecomponents.table.bean.Table;
import org.extremecomponents.table.core.BaseModel;
import org.extremecomponents.table.core.TableConstants;
import org.extremecomponents.table.limit.Sort;

/**
 * The default implementation of the callbacks that handle the retrieving,
 * filtering, and sorting of the collection that gets passed to the
 * eXtremeTable.
 * 
 * @author Jeff Johnston
 */
public final class ProcessRowsCallback implements RetrieveRowsCallback, FilterRowsCallback, SortRowsCallback {
    public Collection retrieveRows(BaseModel model)
            throws Exception {
        Table table = model.getTableHandler().getTable();
        Object items = table.getItems();

        if (items instanceof Collection) {
            return (Collection) items;
        } else if (items instanceof String) {
            return CallbackUtils.findCollection(model, table);
        } else {
            throw new Exception("The eXtremeComponent could not find the Collection of Beans (or Map).");
        }
    }

    public Collection filterRows(BaseModel model, Collection rows)
            throws Exception {
        if (model.getLimit().isFiltered()) {
            Collection collection = new ArrayList();
            FilterPredicate filterPredicate = new FilterPredicate(model);
            CollectionUtils.select(rows, filterPredicate, collection);

            return collection;
        }
        
        return rows;
    }

    public Collection sortRows(BaseModel model, Collection rows)
            throws Exception {
        Sort sort = model.getLimit().getSort();
        String property = sort.getProperty();
        String sortOrder = sort.getSortOrder();

        if (sortOrder.equals(TableConstants.SORT_ASC)) {
            BeanComparator comparator = new BeanComparator(property, new NullComparator());
            Collections.sort((List) rows, comparator);
        } else if (sortOrder.equals(TableConstants.SORT_DESC)) {
            BeanComparator reversedNaturalOrderBeanComparator = new BeanComparator(property, new ReverseComparator(
                    new NullComparator()));
            Collections.sort((List) rows, reversedNaturalOrderBeanComparator);
        }

        return rows;
    }
}