Java Date RFC Format toRFC822Date(Date date)

Description

to RFC Date

License

Open Source License

Declaration

public static String toRFC822Date(Date date) 

Method Source Code

//package com.java2s;
/*/*ww  w.  j  a  va 2  s .  c  om*/
 * ***** BEGIN LICENSE BLOCK *****
 * Zimbra Collaboration Suite Server
 * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016 Synacor, Inc.
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software Foundation,
 * version 2 of the License.
 *
 * 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.
 * You should have received a copy of the GNU General Public License along with this program.
 * If not, see <https://www.gnu.org/licenses/>.
 * ***** END LICENSE BLOCK *****
 */

import java.text.DateFormatSymbols;

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

public class Main {
    private static final String[] DAY_NAME = new String[] { "", "Sun, ", "Mon, ", "Tue, ", "Wed, ", "Thu, ",
            "Fri, ", "Sat, " };
    private static final String[] MONTH_NAME = new String[] { "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
            "Aug", "Sep", "Oct", "Nov", "Dec" };
    private static final String[][] ZONE_INFO = new DateFormatSymbols().getZoneStrings();

    public static String toRFC822Date(Date date) {
        Calendar cal = new GregorianCalendar();
        cal.setTime(date);
        return toRFC822Date(cal);
    }

    public static String toRFC822Date(Calendar cal) {

        String tzabbr = getTimezoneAbbreviation(cal.getTimeZone().getID(), cal.get(Calendar.DST_OFFSET) != 0);
        int tzoffset = (cal.get(Calendar.ZONE_OFFSET) + cal.get(Calendar.DST_OFFSET)) / 60000;
        char tzsign = tzoffset > 0 ? '+' : '-';
        tzoffset = Math.abs(tzoffset);

        StringBuilder sb = new StringBuilder(40);
        sb.append(DAY_NAME[cal.get(Calendar.DAY_OF_WEEK)]);
        append2DigitNumber(sb, cal.get(Calendar.DAY_OF_MONTH)).append(' ');
        sb.append(MONTH_NAME[cal.get(Calendar.MONTH)]).append(' ');
        sb.append(cal.get(Calendar.YEAR)).append(' ');

        append2DigitNumber(sb, cal.get(Calendar.HOUR_OF_DAY)).append(':');
        append2DigitNumber(sb, cal.get(Calendar.MINUTE)).append(':');
        append2DigitNumber(sb, cal.get(Calendar.SECOND)).append(' ');

        sb.append(tzsign);
        append2DigitNumber(sb, tzoffset / 60);
        append2DigitNumber(sb, tzoffset % 60);
        if (tzabbr != null)
            sb.append(" (").append(tzabbr).append(')');
        return sb.toString();
    }

    private static String getTimezoneAbbreviation(String tzid, boolean dst) {
        if (tzid == null)
            return null;

        for (int tzindex = 0; tzindex < ZONE_INFO.length; tzindex++) {
            if (tzid.equalsIgnoreCase(ZONE_INFO[tzindex][0]))
                return dst ? ZONE_INFO[tzindex][4] : ZONE_INFO[tzindex][2];
        }
        return null;
    }

    private static StringBuilder append2DigitNumber(StringBuilder sb, int number) {
        return sb.append((char) ('0' + number / 10)).append((char) ('0' + number % 10));
    }
}

Related

1. rfc822(Date date)
2. rfc822Date(Date date)
3. rfc822Date(final Date val)
4. RFC822Section5Format_to_Date(String time)
5. toRfc822(Calendar cal)
6. translateStartTimeToRFC3339(String startTime)