Java 날짜처리

음력, 음력 -> 양력 변환" href="http://blog.naver.com/levin01/100004872718">양력 -> 음력, 음력 -> 양력 변환

Calendar클래스(GregorianCalendar)를 이용한 달력 출력하기

에릭에반스와 켄트백이 만든 돈과 시간 관련 라이브러리

새로운 Time & Date API

http://www.opengamma.com/blog/2011/jsr-310-experience

yyyyMMddHHmmss

Library

http://joda-time.sourceforge.net/

http://timeandmoney.sourceforge.net/

http://www.date4j.net/

날짜구하기

java.text.DateFormat

java.text.SimpleDateFormat

import java.util.Calendar;
import java.util.Date;

 import java.util.SimpleTimeZone;

    public static Date parseDate(String dateStr) {
        SimpleDateFormat fmt = new SimpleDateFormat("yyyyMMdd");
        SimpleTimeZone timeZone = new SimpleTimeZone(9 * 60 * 60 * 1000, "KST");
        fmt.setTimeZone(timeZone);
        try {
            return fmt.parse(dateStr);
        } catch (ParseException e) {
            return null;
        }
    }

    public static String getDateString(Date date, String format) {
        // 테스트
        if (date == null) {
            return "";
        }
        SimpleDateFormat dateFormat = new SimpleDateFormat(format);
        SimpleTimeZone timeZone = new SimpleTimeZone(9 * 60 * 60 * 1000, "KST");
        dateFormat.setTimeZone(timeZone);
        Calendar cal = dateFormat.getCalendar();
        cal.setTime(date);
        return dateFormat.format(cal.getTime());
    }

    /**
     * 현재 시스템 날짜(yyyyMMdd HH:mm:ss.SSS) 값을 얻어온다.
     * @return ymd
     */
    public static String getTimeSSS() {
        long currentTimes = System.currentTimeMillis();
        String ymd = new SimpleDateFormat("yyyyMMdd HH:mm:ss.SSS").format(new Date(currentTimes));
        return ymd;
    }

요일확인

import java.util.Calendar;
import java.util.GregorianCalendar;

public class WeekdayTest {
   
    public static void main(String args[]){
        boolean b1 = isMatchedWeekday("20080114", Calendar.MONDAY);
        boolean b2 = isMatchedWeekday("20080105", Calendar.SATURDAY);       
        boolean b3 = isMatchedWeekday("20080107", Calendar.MONDAY);
       
        System.out.println(b1);
        System.out.println(b2);
        System.out.println(b3);       
    }
   
    public static boolean isMatchedWeekday(String date, int weekday){
        int year = Integer.parseInt(date.substring(0,4));
        int month = Integer.parseInt(date.substring(4,6))-1;
        int day = Integer.parseInt(date.substring(6,8)); 
        Calendar c = new GregorianCalendar();  
        c.set(year,month,day);
        return (weekday ==c.get(Calendar.DAY_OF_WEEK));
    }   
}

DateUtils

       static final String DAY_FORAMT = "yyyy-MM-dd";

       static final String TIME_FORAMT = "yyyy-MM-dd HH:mm:ss";

       @Test

       public void dateTest() throws Exception {

             Date date = DateUtils.parseDate("1850-01-01 00:00:00", new String[]{TIME_FORAMT});

             int count = 200 * 365;

             System.out.println("Expected print out => Actual print out");

             do {

                    String actualDateString = DateFormatUtils.format(date, TIME_FORAMT);

                    String expectedDateString = DateFormatUtils.format(date, DAY_FORAMT) + " 00:00:00";

                    if (!actualDateString.equals(expectedDateString)) {

                           System.out.println(expectedDateString + " => " + actualDateString);

                    }

                    assertTrue(actualDateString.equals(expectedDateString));

                    date = DateUtils.addDays(date,1);

                    date = DateUtils.truncate(date, Calendar.DATE);

             } while (count-- > 0);

Timezone update

http://java.sun.com/javase/tzupdater_README.html

http://java.sun.com/javase/timezones/