AbstractEntity.java

/*
 * This software was designed and created by Jason Carroll.
 * Copyright (c) 2002, 2003, 2004 Jason Carroll.
 * The author can be reached at jcarroll@cowsultants.com
 * ITracker website: http://www.cowsultants.com
 * ITracker forums: http://www.cowsultants.com/phpBB/index.php
 *
 * This program is free software; you can redistribute it and/or modify
 * it only under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 */

package org.itracker.model;

import org.apache.commons.lang.builder.CompareToBuilder;
import org.apache.commons.lang.builder.EqualsBuilder;
import org.apache.commons.lang.builder.HashCodeBuilder;

import java.io.Serializable;
import java.util.Comparator;
import java.util.Date;

/**
 * This is a POJO Business Domain Object. Hibernate Bean.
 * <p/>
 * <p>
 * All entities are Java Beans and should inherit this class to make sure they
 * are Serializable and Cloneable and have the following fields : an id, a
 * creation date and a last modifiation date.
 * </p>
 *
 * @author ready
 */
public abstract class AbstractEntity implements Entity {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    public static final Comparator<Entity> ID_COMPARATOR = new IdComparator();

    public static final Comparator<AbstractEntity> CREATE_DATE_COMPARATOR = new CreateDateComparator();

    public static final Comparator<AbstractEntity> LAST_MODIFIED_DATE_COMPARATOR = new LastModifiedDateComparator();

    /**
     * System ID
     */
    private Integer id;

    /**
     * Creation date and time.
     */
    private Date createDate = new Date();

    /**
     * Last modification date and time.
     */
    private Date lastModifiedDate = new Date();

    /**
     * Default constructor (required by Hibernate).
     */
    public AbstractEntity() {
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    /**
     * @return creation time stamp or <tt>null</tt> for transient entities
     */
    public Date getCreateDate() {
        if (null == createDate)
            createDate = new Date();
        return new Date(createDate.getTime());
    }

    /**
     * Sets the creation date and time.
     * <p/>
     * <p>
     * The persistence framework automatically sets this property when a new
     * entity is persisted. <br>
     * Note that the value is managed by the persistence framework and may be
     * generated by the database in the future.
     * </p>
     * <p/>
     * <p>
     * The creation time stamp should never change once initialized.
     * </p>
     *
     * @param dateTime creation time stamp
     */
    public void setCreateDate(Date dateTime) {
        if (null == dateTime)
            return;
        this.createDate = new Date(dateTime.getTime());
    }

    /**
     * @return last modification time stamp or <tt>null</tt> for transient
     *         entities
     */
    public Date getLastModifiedDate() {
        if (null == this.lastModifiedDate)
            this.lastModifiedDate = new Date();
        return new Date(lastModifiedDate.getTime());
    }

    /**
     * Sets the last modification date and time.
     * <p/>
     * <p>
     * The persistence framework automatically sets this property to the same
     * value as the createDate property when persisting a new entity and
     * automatically updates it when saving an existing one. <br>
     * Note that the value is managed by the persistence framework and may be
     * generated by the database in the future.
     * </p>
     *
     * @param dateTime last modification time stamp
     */
    public void setLastModifiedDate(Date dateTime) {
        if (null == dateTime)
            return;
        this.lastModifiedDate = new Date(dateTime.getTime());
    }

    /**
     * Returns whether this instance represents a new transient instance.
     *
     * @return <tt>true</tt> if <code>id</code> is <tt>null</tt>
     */
    public boolean isNew() {
        return (this.getId() == null);
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

    /**
     * Compares 2 instances by ID.
     */
    protected static class IdComparator implements Comparator<Entity>, Serializable {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        public int compare(Entity a, Entity b) {
            return new CompareToBuilder().append(a.getId(), b.getId())
                    .toComparison();
        }

    }

    protected static class CreateDateComparator implements
            Comparator<AbstractEntity>, Serializable {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        public int compare(AbstractEntity a, AbstractEntity b) {
            return new CompareToBuilder().append(a.getCreateDate(),
                    b.getCreateDate()).toComparison();
        }

    }

    /**
     * Compares 2 instances by last modified date.
     */
    protected static class LastModifiedDateComparator implements
            Comparator<AbstractEntity>, Serializable {

        /**
         *
         */
        private static final long serialVersionUID = 1L;

        public int compare(AbstractEntity a, AbstractEntity b) {
            return new CompareToBuilder().append(a.getLastModifiedDate(),
                    b.getLastModifiedDate()).toComparison();
        }

    }

    @Override
    public final boolean equals(Object obj) {

        if (this == obj) {
            return true;
        }
        if (isNew() || null == obj) {
            return false;
        }

        if (getClass().equals(obj.getClass())) {
            Entity o = (Entity) obj;
            return new EqualsBuilder()
                    .append(getId(), o.getId()).isEquals();

        }

        return false;

    }

    public final int compareTo(Entity o) {
        if (this.equals(o)) {
            return 0;
        }
        return new CompareToBuilder().append(getClass(), o.getClass(), AbstractEntity.CLASS_COMPARATOR).append(
                getId(), o.getId()).toComparison();
    }

    @Override
    public final int hashCode() {
        return new HashCodeBuilder().append(getClass()).append(getId()).toHashCode();

    }

    private static final Comparator<Class<?>> CLASS_COMPARATOR = new Comparator<Class<?>>() {
        public int compare(Class<?> o1, Class<?> o2) {
            return new CompareToBuilder().append(o1.getSimpleName(), o2.getSimpleName()).append(o1.hashCode(), hashCode()).toComparison();
        }
    };

}