ca.on.gov.jus.icon.common.util.LookupNestedMapHandler.java Source code

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Here is the source code for ca.on.gov.jus.icon.common.util.LookupNestedMapHandler.java

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/** 
 * Copyright 2005 The Ontario Lottery Gamming Corporation, Inc. 
 * Yonge 4120, Toronto, Ontario, M2P 2B8, Canada. 
 * All rights reserved. 
 * OLGC PROPRIETARY/CONFIDENTIAL. 
 * Use is subject to license terms. 
 * Created on Nov 24, 2005 
 */

package ca.on.gov.jus.icon.common.util;

import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.util.HashMap;
import java.util.Map;

import org.apache.commons.dbutils.ResultSetHandler;

/**
 * Implements result set processing logic for the Lookup Manager.
 * Expects a result set with three columns ordered by the first column.
 * The data is organized in a nested map (maps with a map).  The
 * first column (e.g. region_id) is used as the key of the primary map
 * and the corresponding object is another map.  The secondary maps
 * uses the second column as the key (e.g. site_id) and the
 * third colum as the object (e.g. site_name).  Therefore the map
 * containing all sites for a given region can be obtained using
 * a region id.
 *  
 * <p>
 * In the long description, you can use <b>HTML</b> tags to spice it
 * up.  If you use Java keywords, package names, variables, code examples,
 * class names or method names (e.g., <code>method()</code>), place
 * 'code' tags around them.  After the description, edit the tags below.
 * </P>
 *             
 * @see          AnotherClass
 * @see          AnotherClass#methodName
 *
 *  Revision History: 
 * 
 *  Ver.   Date             Author          Description
 *  -----  ----------       --------------  ------------------------------------
 *   1.0   Nov 24, 2005    eborejsza       Initial Creation
 */

public class LookupNestedMapHandler implements ResultSetHandler {

    private static int MAP_RESULT_SET_COLUMNS = 3;

    /**
     * Default constructor.
     */
    public LookupNestedMapHandler() {
        super();
    }

    /**
     * Iterates through the query result set and creates a correctly
     * indexed map of maps.  This is only intended to work with a result
     * set that contains three columns and the first column must
     * cast successfully to a <code>Integer</code> datatype.
     * 
     * @param   rs      The result set that is used to obtain the name/value data.
     * @return   Object   The <code>java.util.Map</code> collection containing the results. 
     * @see org.apache.commons.dbutils.ResultSetHandler#handle(java.sql.ResultSet)
     */
    public Object handle(ResultSet rs) throws SQLException {
        Map results = new HashMap();
        Map nestedMap = new HashMap();
        Integer currentId = null;

        // Get the number of columns in the result set.
        ResultSetMetaData rsmd = rs.getMetaData();
        int cols = rsmd.getColumnCount();

        // Populate the Map with the name value pairs
        // if the result set contains two columns of data.
        if (cols == MAP_RESULT_SET_COLUMNS) {
            while (rs.next()) {
                Object primaryId = rs.getObject(1);
                Object secondaryId = rs.getObject(2);
                Object secondaryValue = rs.getObject(3);

                // Initialize the current id on the first iteration.
                if (currentId == null) {
                    currentId = (Integer) primaryId;
                }

                // Check if the primary id is not the same as the current id.         
                if (currentId.compareTo(primaryId) != 0) {
                    // Put the current nested map into the result map
                    // and create a new nested map.
                    results.put(currentId, nestedMap);
                    nestedMap = new HashMap();
                    currentId = (Integer) primaryId;
                }

                // Put the key & value into the current nested map.
                // This occurs after checking if a new nested map is required.
                nestedMap.put(secondaryId, secondaryValue);
            }

            // Put the final nested map into the results map
            // once the iterations are complete.
            results.put(currentId, nestedMap);
        }

        return results;
    }

}