org.sakaiproject.tool.assessment.qti.util.Iso8601DateFormat.java Source code

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Here is the source code for org.sakaiproject.tool.assessment.qti.util.Iso8601DateFormat.java

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/**********************************************************************************
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 * $Id$
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 *
 * Copyright (c) 2005, 2006, 2008, 2009 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.
 *
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package org.sakaiproject.tool.assessment.qti.util;

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.sakaiproject.tool.assessment.qti.exception.Iso8601FormatException;

/**
 * Based on ISO8601 Specification.
 *
 * @author <a href="mailto:lance@indiana.edu">Lance Speelmon</a>
 * @version $Id$
 */
public class Iso8601DateFormat {
    public static final String BASIC_FORMAT = "yyyyMMdd'T'HHmmssZ";
    private static Log log = LogFactory.getLog(Iso8601DateFormat.class);
    private static final String GMT = "GMT";

    // 20031107T152420-0500  or
    // 2003-11-07T15:24:20-05:00
    private static final Pattern PATTERN_MATCH = Pattern.compile("^(?:(\\d{2,4})-?)?" + // year
            "(?:(\\d{2})-?)?" + // month
            "(\\d{2})?" + // day of month
            "T?" + // time separator
            "(?:(\\d{2}):?)?" + // hour
            "(?:(\\d{2}):?)?" + // minutes
            "(\\d{2})?" + // seconds
            "(Z?|(?:\\+|-).+)?$"); // timezone: -0500 or +08:00 or -05 or Z
    private String pattern;

    /**
     * Creates a new Iso8601DateFormat object.
     */
    public Iso8601DateFormat() {
        log.debug("new Iso8601DateFormat()");
        this.pattern = BASIC_FORMAT;
    }

    /**
     * DOCUMENT ME!
     *
     * @param simpleDateFormatPattern
     *
     * @see java.text.SimpleDateFormat
     */
    public Iso8601DateFormat(String simpleDateFormatPattern) {
        log.debug("new Iso8601DateFormat(String " + simpleDateFormatPattern + ")");
        this.pattern = simpleDateFormatPattern;
    }

    /**
     * DOCUMENTATION PENDING
     *
     * @param date DOCUMENTATION PENDING
     *
     * @return DOCUMENTATION PENDING
     */
    public String format(Date date) {
        log.debug("format(Date " + date + ")");
        SimpleDateFormat sdf = null;
        if (this.pattern == null) {
            sdf = new SimpleDateFormat();
        } else {
            sdf = new SimpleDateFormat(pattern);
        }

        return sdf.format(date);
    }

    /**
     * DOCUMENTATION PENDING
     *
     * @param iso8601String DOCUMENTATION PENDING
     *
     * @return DOCUMENTATION PENDING
     *
     * @throws Iso8601FormatException DOCUMENTATION PENDING
     */
    public Calendar parse(String iso8601String) throws Iso8601FormatException {
        log.debug("parse(String " + iso8601String + ")");
        if (iso8601String == null) {
            throw new Iso8601FormatException("illegal String iso8601TimeInterval argument: iso8601String == null");
        }

        iso8601String = iso8601String.toUpperCase();
        final Matcher matcher = PATTERN_MATCH.matcher(iso8601String);
        if (matcher.matches()) {
            if (log.isDebugEnabled()) {
                for (int i = 0; i <= matcher.groupCount(); i++) {
                    log.debug(i + "=" + matcher.group(i));
                }
            }

            String tz = matcher.group(7);
            Calendar cal = null;
            if ((tz != null) && (tz.length() > 0)) {
                if ("Z".equals(tz)) {
                    tz = "Zulu";
                } else {
                    tz = GMT + tz;
                }

                if (log.isDebugEnabled()) {
                    log.debug("tz=" + tz);
                    log.debug("TimeZone.getID()=" + TimeZone.getTimeZone(tz).getID());
                }

                cal = GregorianCalendar.getInstance(TimeZone.getTimeZone(tz));
            } else {
                cal = GregorianCalendar.getInstance();

                /* data must be zeroed out to counteract now behavior*/
                cal.clear();
            }

            /* year */
            if (matcher.group(1) != null) {
                final int year = Integer.parseInt(matcher.group(1));
                cal.set(Calendar.YEAR, year);
            } else {
                throw new Iso8601FormatException("Year is required");
            }

            /* month */
            if (matcher.group(2) != null) {
                final int month = Integer.parseInt(matcher.group(2)) - 1; // zero based
                cal.set(Calendar.MONTH, month);
            }

            /* date (day) */
            if (matcher.group(3) != null) {
                final int date = Integer.parseInt(matcher.group(3));
                cal.set(Calendar.DAY_OF_MONTH, date);
            }

            /* hour */
            if (matcher.group(4) != null) {
                final int hour = Integer.parseInt(matcher.group(4));
                cal.set(Calendar.HOUR_OF_DAY, hour);
            }

            /* minutes */
            if (matcher.group(5) != null) {
                final int min = Integer.parseInt(matcher.group(5));
                cal.set(Calendar.MINUTE, min);
            }

            /* seconds */
            if (matcher.group(6) != null) {
                final int sec = Integer.parseInt(matcher.group(6));
                cal.set(Calendar.SECOND, sec);
            }

            return cal;
        }

        throw new Iso8601FormatException("ISO8601 format could not be matched");
    }
}