onecolumnmapping.java

Mandarax是一个规则引擎的纯Java实现。它支持多类型的事实和基于反映的规则

/*
 * Copyright (C) 1999-2004 <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</a>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.mandarax.sql;


import java.sql.ResultSet;
import java.sql.SQLException;

/**
 * Object relational mapping where the object is just the value of the
 * one (and probably only) column. This is suitable for queries like
 * <code>SELECT NAME FROM CUSTOMERS WHERE ID=1</code>.
 * @author <A href="http://www-ist.massey.ac.nz/JBDietrich" target="_top">Jens Dietrich</A>
 * @version 3.4 <7 March 05>
 * @since 1.6
 */
public class OneColumnMapping implements SQLObjectRelationalMapping {

    private Class targetType = null;

    /**
     * Constructor.
     */
    public OneColumnMapping() {
        super ();
    }

    /**
     * Constructor.
     * @param clazz a target type
     */
    public OneColumnMapping(Class clazz) {
        super ();

        setTargetType (clazz);
    }

    /**
     * Build a java object from a record.
     * @return an object
     * @param record a result set
     */
    public Object buildObject(ResultSet record) throws SQLException {
        return record.getObject (1);
    }

    /**
     * Get the target class.
     * @return a class
     */
    public Class getTargetType() {
        return targetType;
    }

    /**
     * Set the target class.
     * @param clazz a class
     */
    public void setTargetType(Class clazz) {
        targetType = clazz;
    }

    /**
     * Compare objects.
     * @param obj another object
     * @return a boolean
     */
    public boolean equals(Object obj) {
        if((obj != null) && (obj instanceof OneColumnMapping)) {
            OneColumnMapping map = (OneColumnMapping) obj;

            return(targetType == null)
                  ? map.targetType == null
                  : targetType.equals (map.targetType);
        }

        return false;
    }

    /**
     * Get the hash code.
     * @return the hash code
     */
    public int hashCode() {
        return getClass ().hashCode () ^ ((targetType == null)
                                          ? 0
                                          : targetType.hashCode ());
    }
}