datetimecomparator.java

实现了Jms的服务器源码,支持多种适配器,DB,FTP,支持多种数据库

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 *    copy of this document.
 *
 * 2. Redistributions in binary form must reproduce the
 *    above copyright notice, this list of conditions and the
 *    following disclaimer in the documentation and/or other
 *    materials provided with the distribution.
 *
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 *    products derived from this Software without prior written
 *    permission of Exoffice Technologies.  For written permission,
 *    please contact [e-mail].
 *
 * 4. Products derived from this Software may not be called "Exolab"
 *    nor may "Exolab" appear in their names without prior written
 *    permission of Exoffice Technologies. Exolab is a registered
 *    trademark of Exoffice Technologies.
 *
 * 5. Due credit should be given to the Exolab Project
 *    (http://www.exolab.org/).
 *
 * THIS SOFTWARE IS PROVIDED BY EXOFFICE TECHNOLOGIES AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT
 * NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL
 * EXOFFICE TECHNOLOGIES OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Copyright 2000 (C) Exoffice Technologies Inc. All Rights Reserved.
 *
 * $Id: DateTimeComparator.java,v 1.4 2003/08/17 01:32:25 tanderson Exp $
 *
 * Date         Author  Changes
 * $Date	    jimm    Created
 */


package org.exolab.jms.persistence;

import java.util.Comparator;

import javax.jms.JMSException;


/**
 * A comparator class that iplements a date/time comparison for
 * PersistentMessage
 *
 * @version     $Revision: 1.4 $ $Date: 2003/08/17 01:32:25 $
 * @author      <a href="mailto:[e-mail]">Jim Mourikis</a>
 */
public class DateTimeComparator implements Comparator {

    /**
     * Default constructor does nothing.
     *
     */
    public DateTimeComparator() {

    }


    /**
     * Implements the compare operator.
     * Compares its two arguments for order. Returns a negative integer, zero,
     * or a positive integer as the first argument is less than, equal to,
     * or greater than the second.
     *
     * @param Object object 1 to compare
     * @param Object object 2 ro compare to.
     * @return int returns -1, 0, 1 if the first argument is less than,
     *		   equal to, or greater than the second.
     * @exception ClassCastException if object types are unknown
     *
     */
    public int compare(Object o1, Object o2) throws ClassCastException {
        int status;

        if (o1 == null && o2 == null)
            status = 0;
        else if (o1 == null)
            status = -1;
        else if (o2 == null)
            status = 1;
        else if (o1 instanceof PersistentMessage &&
            o2 instanceof PersistentMessage) {
            PersistentMessage m1 = (PersistentMessage) o1;
            PersistentMessage m2 = (PersistentMessage) o2;
            long t1;
            long t2;

            try {
                t1 = m1.getMessage().getJMSTimestamp();
            } catch (JMSException e1) {
                t1 = 0;
            }
            try {
                t2 = m2.getMessage().getJMSTimestamp();
            } catch (JMSException e2) {
                t2 = 0;
            }

            if (t1 < t2)
                status = -1;
            else if (t1 == t2)
                status = 0;
            else
                status = 1;
        } else {
            throw new ClassCastException("Unknown Object");
        }
        return status;
    }


    /**
     * Indicates whether some other object is "equal to" this Comparator.
     * This method must obey the general contract of Object.equals(Object).
     *
     * @param Object the object to compare to
     * @return boolean true iff objects are equal
     *
     */
    public boolean equals(Object ob) {
        boolean status = false;

        if (ob instanceof DateTimeComparator) status = true;

        return status;
    }


} // End DateTimeComparator