TimeUtil.java

/**********************************************************************************
 * $URL: https://source.sakaiproject.org/svn/sam/trunk/samigo-app/src/java/org/sakaiproject/tool/assessment/ui/listener/util/TimeUtil.java $
 * $Id: TimeUtil.java 121763 2013-03-26 08:25:33Z david.horwitz@uct.ac.za $
 ***********************************************************************************
 *
 * Copyright (c) 2006, 2008 The Sakai Foundation
 *
 * Licensed under the Educational Community License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *       http://www.opensource.org/licenses/ECL-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 **********************************************************************************/


package org.sakaiproject.tool.assessment.ui.listener.util;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.sakaiproject.time.cover.TimeService;

/**
 * <p>Description: Time conversion utility class</p>
 */

public class TimeUtil 
{

  private static Log log = LogFactory.getLog(TimeUtil.class);

  private TimeZone m_client_timezone= null;
  private TimeZone m_server_timezone= null;

  public TimeUtil() {
    m_client_timezone= TimeService.getLocalTimeZone();
    m_server_timezone= TimeZone.getDefault();
  }


  /**
  * Convert a String reprepsentation of date and time in the client TimeZone 
  * to Date representation of date and time  in server TimeZone
  * before saving to DB.
  * tz1 is the client timezone,  tz2 is the server timezone
  */

  public Date convertFromTimeZone1StringToServerDate
        (SimpleDateFormat ndf, String tz1string, TimeZone tz1){
    Date serverDate= null;
    try {
      ndf.setTimeZone(tz1);
      serverDate= ndf.parse(tz1string);
    }
    catch(Exception e){
      e.printStackTrace();
    }

     return serverDate;

  }


  /**
  * Convert a Date reprepsentation of date and time in the server TimeZone 
  * to String representation of date and time  in client TimeZone
  * used for display. 
  * tz1 is the client timezone,  tz2 is the server timezone
  */

  public String convertFromServerDateToTimeZone2String 
    (SimpleDateFormat ndf, Date tz2Date, TimeZone tz1){
    // for display
    Calendar cal1= new GregorianCalendar(tz1);
    ndf.setCalendar(cal1);
    String clientStr= ndf.format(tz2Date);

    return clientStr;
  }

  /**
  * Convert a String representation of date and time to Date on the server timezone 
  */

  public Date getServerDateTime(SimpleDateFormat ndf, String clientString){
    Date serverDate = null;
    try {
      if ((m_client_timezone !=null) && (m_server_timezone!=null) 
	&& (!m_client_timezone.hasSameRules(m_server_timezone))) {

        serverDate =convertFromTimeZone1StringToServerDate 
                        (ndf, clientString, m_client_timezone);
      }
      else {
        serverDate= ndf.parse(clientString);
      }
    }
    catch (ParseException e) {
    	log.warn("can not parse the string, " + clientString + ", into a Date using format: " + ndf.toPattern());
    	if (log.isDebugEnabled()) {
    		e.printStackTrace();
    	}
	}
    return serverDate;
  }


  /**
  * Convert a Date reprepsentation of date and time to String in the client timezone for display
  */

  public String getDisplayDateTime(SimpleDateFormat ndf, Date serverDate ){
    String displayDate = "";
     //we can't format a null date
    if (serverDate == null) {
    	return displayDate;
    }
    
    try {
      if ((m_client_timezone !=null) && (m_server_timezone!=null) 
	&& (!m_client_timezone.hasSameRules(m_server_timezone))) {

        displayDate = convertFromServerDateToTimeZone2String
			(ndf, serverDate, m_client_timezone);
      }
      else {
        displayDate= ndf.format(serverDate);
      }
    }
    catch (RuntimeException e){
      log.warn("can not format the Date to a string");
    }
    return displayDate;
  }



}