Constants.java

/*
 Copyright (c) 2002, 2010, Oracle and/or its affiliates. All rights reserved.
 

  The MySQL Connector/J is licensed under the terms of the GPLv2
  <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most MySQL Connectors.
  There are special exceptions to the terms and conditions of the GPLv2 as it is applied to
  this software, see the FLOSS License Exception
  <http://www.mysql.com/about/legal/licensing/foss-exception.html>.

  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, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
  Floor, Boston, MA 02110-1301  USA



 */
package com.mysql.jdbc;

/**
 * Represents various constants used in the driver.
 * 
 * @author Mark Matthews
 * 
 * @version $Id$
 */
public class Constants {
	/**
	 * Avoids allocation of empty byte[] when representing 0-length strings.
	 */
	public final static byte[] EMPTY_BYTE_ARRAY = new byte[0];

	/**
	 * I18N'd representation of the abbreviation for "ms"
	 */
	public final static String MILLIS_I18N = Messages.getString("Milliseconds");
	
	public final static byte[] SLASH_STAR_SPACE_AS_BYTES = new byte[] {
			(byte) '/', (byte) '*', (byte) ' ' };

	public final static byte[] SPACE_STAR_SLASH_SPACE_AS_BYTES = new byte[] {
			(byte) ' ', (byte) '*', (byte) '/', (byte) ' ' };

	/*
	 * We're still stuck on JDK-1.4.2, but want the Number.valueOf() methods
	 */
	private static final Character[] CHARACTER_CACHE = new Character[128];

	private static final int BYTE_CACHE_OFFSET = 128;

	private static final Byte[] BYTE_CACHE = new Byte[256];

	private static final int INTEGER_CACHE_OFFSET = 128;

	private static final Integer[] INTEGER_CACHE = new Integer[256];

	private static final int SHORT_CACHE_OFFSET = 128;

	private static final Short[] SHORT_CACHE = new Short[256];

	private static final Long[] LONG_CACHE = new Long[256];

	private static final int LONG_CACHE_OFFSET = 128;

	static {
		for (int i = 0; i < CHARACTER_CACHE.length; i++) {
			CHARACTER_CACHE[i] = new Character((char) i);
		}

		for (int i = 0; i < INTEGER_CACHE.length; i++) {
			INTEGER_CACHE[i] = new Integer(i - 128);
		}

		for (int i = 0; i < SHORT_CACHE.length; i++) {
			SHORT_CACHE[i] = new Short((short) (i - 128));
		}

		for (int i = 0; i < LONG_CACHE.length; i++) {
			LONG_CACHE[i] = new Long(i - 128);
		}

		for (int i = 0; i < BYTE_CACHE.length; i++)
			BYTE_CACHE[i] = new Byte((byte) (i - BYTE_CACHE_OFFSET));
	}

	/** Same behavior as JDK-1.5's Constants.characterValueOf(int) */
	
	public static Character characterValueOf(char c) {
		if (c <= 127) {
			return CHARACTER_CACHE[c];
		}

		return new Character(c);
	}

	/** Same behavior as JDK-1.5's Byte.valueOf(int) */

	public static final Byte byteValueOf(byte b) {
		return BYTE_CACHE[b + BYTE_CACHE_OFFSET];
	}

	/** Same behavior as JDK-1.5's Integer.valueOf(int) */

	public static final Integer integerValueOf(int i) {
		if (i >= -128 && i <= 127) {
			return INTEGER_CACHE[i + INTEGER_CACHE_OFFSET];
		}

		return new Integer(i);
	}

	/** Same behavior as JDK-1.5's Constants.shortValueOf(int) */
	
	public static Short shortValueOf(short s) {

		if (s >= -128 && s <= 127) {
			return SHORT_CACHE[s + SHORT_CACHE_OFFSET];
		}
		
		return new Short(s);
	}

	/** Same behavior as JDK-1.5's Long.valueOf(int) */
	
	public static final Long longValueOf(long l) {
		if (l >= -128 && l <= 127) {
			return LONG_CACHE[(int) l + LONG_CACHE_OFFSET];
		}

		return new Long(l);
	}

	/**
	 * Prevents instantiation
	 */
	private Constants() {
	}
}