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SmartWeb is a web application development meta framework based on Jakarta Struts, Hibernate and other open source frameworks and libraries.
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/*
 * The SmartWeb Framework
 * Copyright (C) 2004-2006
 *
 * 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 2.1 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., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 *
 * For further informations on the SmartWeb Framework please visit
 *
 *                        http://smartweb.sourceforge.net
 */
package net.smartlab.web;

import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Types;

import org.hibernate.Hibernate;
import org.hibernate.HibernateException;
import org.hibernate.usertype.UserType;

/**
 * Represents a meta type used to constraint a property to accept only
 * pre-defined admitted values. Whenever a property needs some sort of
 * constraint on assignable values, like person gender or process status, a
 * subclass of Enumeration can be used to enumerate all possible
 * values.
 * 
 * @author rlogiacco
 */
public abstract class Enumeration implements UserType, Serializable {

	private final static long serialVersionUID = 8849967605617496075L;

	/**
	 * Type of the persisted field reference.
	 */
	private final static int[] TYPES = new int[] {Types.SMALLINT};

	/**
	 * The unique identifier used to represent the choice onto the persisted
	 * field.
	 * 
	 * @uml.property name="id"
	 */
	private final int id;

	/**
	 * A brief, human understandable, description of the choice.
	 * 
	 * @uml.property name="display"
	 */
	private final String display;


	/**
	 * Default constructor used for internal purposes only.
	 */
	protected Enumeration() {
		// Default constructor
		this.id = -1;
		this.display = null;
	}

	/**
	 * Constructs an available choice on a unique identifier and a brief, human
	 * understandable, description.
	 * 
	 * @param id the unique identifier for this choice.
	 * @param display a short, human understandable, description of the choice.
	 */
	protected Enumeration(int id, String display) {
		this.id = id;
		this.display = display;
	}

	/**
	 * Returns the unique identifier for the choice.
	 * 
	 * @return the unique identifier for the choice.
	 * @uml.property name="id"
	 */
	public int getId() {
		return id;
	}

	/**
	 * Returns the brief description of the choice.
	 * 
	 * @return the brief description of the choice.
	 * @uml.property name="display"
	 */
	public String getDisplay() {
		return display;
	}

	/**
	 * Decodes a unique identifier into an instance of this class. This method
	 * can not return null values, instead it should define
	 * a default value.
	 * 
	 * @param id the identifier to decode.
	 * @return an instance of this class.
	 */
	public abstract Enumeration decode(int id);
	
	/**
	 * @see java.lang.Object#equals(java.lang.Object)
	 */
	public boolean equals(Object other) {
		if (other != null && this.getClass().equals(other.getClass())) {
			if (((Enumeration)other).id == id) {
				return true;
			}
		}
		return false;
	}
	
	/**
	 * @see java.lang.Object#hashCode()
	 */
	public int hashCode() {
		return id;
	}

	/**
	 * @see org.hibernate.usertype.UserType#deepCopy(java.lang.Object)
	 */
	public Object deepCopy(Object value) throws HibernateException {
		return value;
	}

	/**
	 * @see org.hibernate.usertype.UserType#equals(java.lang.Object,
	 *      java.lang.Object)
	 */
	public boolean equals(Object src, Object dst) throws HibernateException {
		if (src == dst) {
			return true;
		}
		if (src == null || dst == null) {
			return false;
		}
		return Hibernate.INTEGER.isEqual(src, dst);
	}

	/**
	 * @see org.hibernate.usertype.UserType#isMutable()
	 */
	public boolean isMutable() {
		return false;
	}

	/**
	 * @see org.hibernate.usertype.UserType#nullSafeGet(java.sql.ResultSet,
	 *      java.lang.String[], java.lang.Object)
	 */
	public Object nullSafeGet(ResultSet rows, String[] names, Object owner) throws HibernateException, SQLException {
		try {
			int id = ((Integer)Hibernate.INTEGER.nullSafeGet(rows, names[0])).intValue();
			return this.decode(id);
		} catch (NullPointerException npe) {
			return null;
		}
	}

	/**
	 * @see org.hibernate.usertype.UserType#nullSafeSet(java.sql.PreparedStatement,
	 *      java.lang.Object, int)
	 */
	public void nullSafeSet(PreparedStatement statement, Object value, int index) throws HibernateException,
			SQLException {
		if (value == null) {
			statement.setNull(index, TYPES[0]);
		} else if (value instanceof String) {
			statement.setString(index, (String)value);
		} else if (value instanceof Number) {
			statement.setInt(index, ((Number)value).intValue());
		} else {
			try {
				statement.setInt(index, ((Enumeration)value).getId());
			} catch (ClassCastException cce) {
				throw new HibernateException(cce);
			}
		}
	}

	/**
	 * @see org.hibernate.usertype.UserType#returnedClass()
	 */
	public Class returnedClass() {
		return this.getClass();
	}

	/**
	 * @see org.hibernate.usertype.UserType#sqlTypes()
	 */
	public int[] sqlTypes() {
		return TYPES;
	}

	/**
	 * @see org.hibernate.usertype.UserType#assemble(java.io.Serializable,
	 *      java.lang.Object)
	 */
	public Object assemble(Serializable arg0, Object arg1) throws HibernateException {
		return null;
		// FIXME: may be an HibernateException is better
	}

	/**
	 * @see org.hibernate.usertype.UserType#disassemble(java.lang.Object)
	 */
	public Serializable disassemble(Object arg0) throws HibernateException {
		return null;
		// FIXME: may be an HibernateException is better
	}

	/**
	 * @see org.hibernate.usertype.UserType#hashCode(java.lang.Object)
	 */
	public int hashCode(Object obj) throws HibernateException {
		return ((Enumeration)obj).getId();
	}

	/**
	 * @see org.hibernate.usertype.UserType#replace(java.lang.Object,
	 *      java.lang.Object, java.lang.Object)
	 */
	public Object replace(Object arg0, Object arg1, Object arg2) throws HibernateException {
		return null;
		// FIXME: may be an HibernateException is better
	}
}