net.java.dev.webdav.jaxrs.xml.elements.Rfc3339DateTimeFormat Maven / Gradle / Ivy

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/*
 * #%L
 * WebDAV Support for JAX-RS
 * %%
 * Copyright (C) 2008 - 2014 The java.net WebDAV Project
 * %%
 * 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, either version 3 of the 
 * License, or (at your option) any later version.
 * 
 * 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
 * .
 * #L%
 */

package net.java.dev.webdav.jaxrs.xml.elements;

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

/**
 * RFC 3339 date-time format

 * 
 * This class formats and parses dates using the ISO 8601 compliant pattern [YYYY]-[MM]-[DD]T[hh]:[mm]:[ss].([fff])[OFS]. Parsing and formatting are handled in
 * different ways to provide at-most stability and compatibility. While formatting always will produce a String in full UTC notation (containing time offset
 * literal 'Z' and fraction of seconds), parsing is flexible and can handle not only optional fraction of seconds, but also numeric time offsets in addition to
 * the time offset literal 'Z'.
 * 
 * @author Markus KARG ([email protected])
 */
@SuppressWarnings("serial")
public final class Rfc3339DateTimeFormat extends SimpleDateFormat {

	private static final String DEFAULT_PATTERN = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'";

	public Rfc3339DateTimeFormat() {
		super(DEFAULT_PATTERN, Locale.US);
		this.calendar = Calendar.getInstance(TimeZone.getTimeZone("UTC"));
	}

	@Override
	public final Date parse(final String text) throws ParseException {
		final String patchedText = this.ignoreTimeOffsetColon(text);

		final String pattern = this.buildPatternVariant(patchedText);

		if (!pattern.equals(DEFAULT_PATTERN))
			this.applyPattern(pattern);

		return super.parse(patchedText);
	}

	private final String buildPatternVariant(final String text) {
		final StringBuilder pattern = new StringBuilder("yyyy-MM-dd'T'HH:mm:ss");
		this.addFractionToPattern(pattern, text);
		this.addTimeOffsetToPattern(pattern, text);
		return pattern.toString();
	}

	private final void addFractionToPattern(final StringBuilder pattern, final String text) {
		if (text.lastIndexOf('.') != -1)
			pattern.append(".SSS");
	}

	private final void addTimeOffsetToPattern(final StringBuilder pattern, final String text) {
		final boolean appendAsLiteral = text.charAt(text.length() - 1) == 'Z';

		if (appendAsLiteral)
			pattern.append('\'');

		pattern.append('Z');

		if (appendAsLiteral)
			pattern.append('\'');
	}

	private final String ignoreTimeOffsetColon(final String text) throws ParseException {
		if (text == null || text.isEmpty())
			throw new ParseException("Cannot parse empty text", 0);

		if (text.charAt(text.length() - 1) == 'Z')
			return text;

		if (text.charAt(text.length() - 3) != ':')
			throw new ParseException("According to RFC 3339 time offset must contain colon separator.", text.length() - 2);

		return new StringBuilder(text).deleteCharAt(text.length() - 3).toString();
	}

}