vaadin-framework/src/com/itmill/toolkit/terminal/gwt/client/util/SimpleDateFormat.java

/*
 * Copyright 2006 Robert Hanson <iamroberthanson AT gmail.com>
 * 
 * Licensed under the Apache 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.apache.org/licenses/LICENSE-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.
 */
package com.itmill.toolkit.terminal.gwt.client.util;

import java.util.Date;

/**
 * <dl>
 * <dt><b>Title: </b>
 * <dd>SimpleDateFormat</dd>
 * <p>
 * <dt><b>Description: </b>
 * <dd>GWT does not implement any of the java.text package, so this class tries
 * to fill the void of the missing java.text.SimpleDateFormat class. This
 * version however only supports a subset of the date and time patterns
 * supported by its java.text counterpart. The pattern symbols supported by this
 * class are:
 * <dl>
 * <dt><b>E</b></dt>
 * <dd>Day in a week</dd>
 * <dt><b>d</b></dt>
 * <dd>Day of the month</dd>
 * <dt><b>y</b></dt>
 * <dd>Year</dd>
 * <dt><b>M</b></dt>
 * <dd>Month January, Jan, 01, 1</dd>
 * <dt><b>H</b></dt>
 * <dd>Hour in 24 hour format (0-23)</dd>
 * <dt><b>h</b></dt>
 * <dd>Hour in 12 hour format (1-12)</dd>
 * <dt><b>m</b></dt>
 * <dd>Minute of the hour </dd>
 * <dt><b>s</b></dt>
 * <dd>Seconds of the minute</dd>
 * <dt><b>a</b></dt>
 * <dd>am/pm</dd>
 * </dl>
 * All characters that are not recognised as a date format character are
 * translated literally into the output string. <br/> </dd>
 * <p>
 * </dl>
 * <p>
 * A simple date parsing facility has also been implemented resembling the java
 * prototype. You can currently parse most numeric patterns but no temporal
 * literals (such as day or month names).
 * </p>
 * 
 * @author <a href="mailto:jasone@greenrivercomputing.com">Jason Essington</a>
 * @author <a href="mailto:g.georgovassilis@gmail.com">George Georgovassilis</a>
 * @version $Revision: 0.0 $
 */
public class SimpleDateFormat {
	private String format;
	private DateLocale locale = new DateLocale();

	/**
	 * Gets the support locale for formatting and parsing dates
	 * 
	 * @return
	 */
	public DateLocale getLocale() {
		return locale;
	}

	public void setLocale(DateLocale locale) {
		this.locale = locale;
	}

	public SimpleDateFormat(String pattern) {
		format = pattern;
	}

	public String format(Date date) {
		String f = "";
		if (format != null && format.length() > 0) {
			String lastTokenType = null;
			String currentToken = "";
			for (int i = 0; i < format.length(); i++) {
				String thisChar = format.substring(i, i + 1);
				String currentTokenType = DateLocale.SUPPORTED_DF_TOKENS
						.contains(thisChar) ? thisChar : "";
				if (currentTokenType.equals(lastTokenType) || i == 0) {
					currentToken += thisChar;
					lastTokenType = currentTokenType;
				} else {
					if ("".equals(lastTokenType))
						f += currentToken;
					else
						f += handleToken(currentToken, date);
					currentToken = thisChar;
					lastTokenType = currentTokenType;
				}
			}
			if ("".equals(lastTokenType))
				f += currentToken;
			else
				f += handleToken(currentToken, date);
		}
		return f;
	}

	/**
	 * takes a date format string and returns the formatted portion of the date.
	 * For instance if the token is MMMM then the full month name is returned.
	 * 
	 * @param token
	 *            date format token
	 * @param date
	 *            date to format
	 * @return formatted portion of the date
	 */
	private String handleToken(String token, Date date) {
		String response = token;
		String tc = token.substring(0, 1);
		if (DateLocale.TOKEN_DAY_OF_WEEK.equals(tc)) {
			if (token.length() > 3)
				response = locale.getWEEKDAY_LONG()[date.getDay()];
			else
				response = locale.getWEEKDAY_SHORT()[date.getDay()];
		} else if (DateLocale.TOKEN_DAY_OF_MONTH.equals(tc)) {
			if (token.length() == 1)
				response = Integer.toString(date.getDate());
			else
				response = twoCharDateField(date.getDate());
		} else if (DateLocale.TOKEN_MONTH.equals(tc)) {
			switch (token.length()) {
			case 1:
				response = Integer.toString(date.getMonth() + 1);
				break;
			case 2:
				response = twoCharDateField(date.getMonth() + 1);
				break;
			case 3:
				response = locale.MONTH_SHORT[date.getMonth()];
				break;
			default:
				response = locale.MONTH_LONG[date.getMonth()];
				break;
			}
		} else if (DateLocale.TOKEN_YEAR.equals(tc)) {
			if (token.length() >= 2)
				response = Integer.toString(date.getYear() + 1900);
			else
				response = twoCharDateField(date.getYear());
		} else if (DateLocale.TOKEN_HOUR_12.equals(tc)) {
			int h = date.getHours();
			if (h == 0)
				h = 12;
			else if (h > 12)
				h -= 12;
			// if (token.length() > 1)
			response = twoCharDateField(h);
			// else
			// response = Integer.toString(h);
		} else if (DateLocale.TOKEN_HOUR_24.equals(tc)) {
			// if (token.length() > 1)
			response = twoCharDateField(date.getHours());
			// else
			// response = Integer.toString(date.getHours());
		} else if (DateLocale.TOKEN_MINUTE.equals(tc)) {
			// if (token.length() > 1)
			response = twoCharDateField(date.getMinutes());
			// else
			// response = Integer.toString(date.getMinutes());
		} else if (DateLocale.TOKEN_SECOND.equals(tc)) {
			// if (token.length() > 1)
			response = twoCharDateField(date.getSeconds());
			// else
			// response = Integer.toString(date.getSeconds());
		} else if (DateLocale.TOKEN_AM_PM.equals(tc)) {
			int hour = date.getHours();
			if (hour > 11)
				response = DateLocale.getPM();
			else
				response = DateLocale.getAM();
		}
		return response;
	}

	/**
	 * This is basically just a sneaky way to guarantee that our 1 or 2 digit
	 * numbers come out as a 2 character string. we add an arbitrary number
	 * larger than 100, convert this new number to a string, then take the right
	 * most 2 characters.
	 * 
	 * @param num
	 * @return
	 */
	private String twoCharDateField(int num) {
		String res = Integer.toString(num + 1900);
		res = res.substring(res.length() - 2);
		return res;
	}

	private static Date newDate(long time) {
		return new Date(time);
	}

	/**
	 * Parses text and returns the corresponding date object.
	 * 
	 * @param source
	 * @return java.util.Date
	 */
	public Date parse(String source) {
		return SimpleDateParser.parse(source, format);
	};

}