[Java] GMT/UTC 날짜 변환

GMT/UTC 표준 시간 변환

글로벌 프로젝트 중 PG사로부터 결제완료 일자를 아래와 같은 생소한 format 으로 리턴 받은적이 있는데 컨버트 과정을 거쳐 해결함.

• Response date : 31/3/2015 4:44:30 PM
• Malay : GMT +8
• Korea : GMT +9 

/* 작성일 : 2013.11.27
 * 내 용 : GMT/UTC 일시 변환
 */
public void getConvert(ParameterMap parameterMap) throws Exception {
    //31/3/2015 4:01:59 PM ---> yyyy-MM-dd HH:mm:ss 변환
    logger.debug("TIMES " + convertToDate("31/3/2015 4:44:30 PM"));
    logger.debug("TIMES " + utcToLocaltime(convertToDate("31/3/2015 4:44:30 PM")));
}

/* convertToDate
 * @param datetime
 * SimpleDateFormat("yyyy-MM-dd HH:mm:ss") HH 대문자 : 24 Hour
 * 소문자 : 12 Hour  
 */
public static String convertToDate(String inputDate) throws Exception{
    String dateTime = inputDate;
    SimpleDateFormat format = new SimpleDateFormat("dd/MM/yyyy hh:mm:ss a", Locale.US);
    Date parseDate = null;
    String convertedDate = null;
	 
    try {
        parseDate = format.parse(dateTime);
        DateFormat dateFormatNeeded = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        convertedDate = dateFormatNeeded.format(parseDate);  
    } catch (ParseException e) {
        logger.error("error " + e);
        throw new Exception(e);
    }
	
    return convertedDate;
}


/* UTC time to local time
 */
public static String utcToLocaltime(String datetime) throws Exception {
    String locTime = null;
    //TimeZone tz = TimeZone.getTimeZone("GMT+08:00"); 해당 국가 일시 확인 할 때, 한쿸은 +9
    TimeZone tz = TimeZone.getDefault();
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
	
    try {
        Date parseDate = sdf.parse(datetime);
        long milliseconds = parseDate.getTime();
        int offset = tz.getOffset(milliseconds);
        locTime = sdf.format(milliseconds + offset);
        locTime = locTime.replace("+0000", "");
    } catch(Exception e) {
        e.printStackTrace();
        throw new Exception(e);
    }
	
    return locTime;
}
 
/**
 * local time to UTC time
 */
public static String localtimeToUTC(String inputdatetime) throws Exception {
    String utcTime = null;
    SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); 
    TimeZone tz = TimeZone.getDefault();
	 
    try {
        Date parseDate = sdf.parse(inputdatetime);
        long milliseconds = parseDate.getTime();
        int offset = tz.getOffset(milliseconds);
        utcTime = sdf.format(milliseconds - offset);
        utcTime = utcTime.replace("+0000", "");
    } catch (Exception e) {
        e.printStackTrace();
        throw new Exception(e);
    }
	 
    return utcTime;
}