processrowscallback.java

分页查询控件 分页查询控件

/*
 * 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.base.BaseModel;
import org.extremecomponents.table.bean.Table;
import org.extremecomponents.table.core.ParameterRegistry;
import org.extremecomponents.table.handler.FilterPredicate;
import org.extremecomponents.table.handler.SortHandler;
import org.extremecomponents.util.ExtremeUtils;

/**
 * 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();

        List list = (List) ExtremeUtils.retrieveFromScope(model.getPageContext(), table.getCollection(), table
                .getScope());
        if (list == null) {
            throw new Exception(
                    "The eXtremeComponent could not find the List of Beans (or Map) identified by the collection and scope attributes.");
        }
        
        return list;
    }

    public Collection filterRows(BaseModel model, Collection rows)
            throws Exception {
        List results = new ArrayList();
        FilterPredicate filterPredicate = new FilterPredicate(model);
        CollectionUtils.select(rows, filterPredicate, results);

        return results;
    }

    public Collection sortRows(BaseModel model, Collection rows)
            throws Exception {
        String property = model.getSortHandler().getSortableProperty();
        String sortOrder = model.getRegistry().getParameter(ParameterRegistry.SORT + property);

        if (sortOrder.equals(SortHandler.SORT_ASC_)) {
            BeanComparator comparator = new BeanComparator(property, new NullComparator());
            Collections.sort((List) rows, comparator);
        } else if (sortOrder.equals(SortHandler.SORT_DESC_)) {
            BeanComparator reversedNaturalOrderBeanComparator = new BeanComparator(property, new ReverseComparator(
                    new NullComparator()));
            Collections.sort((List) rows, reversedNaturalOrderBeanComparator);
        }

        return rows;
    }
}