MemorySize.java

/*
 * Copyright (C) 2006-2008 Alfresco Software Limited.
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */

package org.alfresco.jlan.util;

/**
 * Memory Size Class
 * 
 * <p>Convenience class to convert memory size value specified as 'nK' for kilobytes, 'nM' for megabytes and 'nG' for
 * gigabytes, to an absolute value.
 *
 * @author gkspencer
 */
public class MemorySize {

	//	Convertor constants
	
	public static final long KILOBYTE		= 1024L;
	public static final long MEGABYTE		= 1024L * KILOBYTE;
	public static final long GIGABYTE		= 1024L * MEGABYTE;
	public static final long TERABYTE		= 1024L * GIGABYTE;
	
	/**
	 * Convert a memory size to an integer byte value.
	 * 
	 * @param memSize String
	 * @return int
	 * @exception NumberFormatException
	 */
	public static final int getByteValueInt(String memSize) {
		return (int) (getByteValue(memSize) & 0xFFFFFFFFL);
	}

	/**
	 * Convert a memory size to a byte value
	 * 
	 * @param memSize String
	 * @return long
	 * @exception NumberFormatException
	 */
	public static final long getByteValue(String memSize) {
		
		//	Check if the string is valid
		
		if ( memSize == null || memSize.length() == 0)
			return -1L;
			
		//	Check for a kilobyte value

		String sizeStr = memSize.toUpperCase();
		long mult = 1;
		long val  = 0;
				
		if ( sizeStr.endsWith("K")) {

			//	Use the kilobyte multiplier
			
			mult = KILOBYTE;
			val = getValue(sizeStr);
		}
		else if ( sizeStr.endsWith("M")) {

			//	Use the megabyte nultiplier
			
			mult = MEGABYTE;			
			val = getValue(sizeStr);
		}
		else if ( sizeStr.endsWith("G")) {

			//	Use the gigabyte multiplier
			
			mult = GIGABYTE;			
			val = getValue(sizeStr);
		}
		else if ( sizeStr.endsWith("T")) {
			
			//	Use the terabyte multiplier
			
			mult = TERABYTE;
			val = getValue(sizeStr);
		}
		else {
			
			//	Convert a numeric byte value

			val = Long.valueOf(sizeStr).longValue();
		}
		
		//	Apply the multiplier
		
		return val * mult;
	}
	
	/**
	 * Get the size value from a string and return the numeric value
	 * 
	 * @param val String
	 * @return long
	 * @exception NumberFormatException
	 */		
	private final static long getValue(String val) {
		
		//	Strip the trailing size indicator
		
		String sizStr = val.substring(0, val.length() - 1);
		return Long.valueOf(sizStr).longValue();
	}
	
	/**
	 * Return a byte value as a kilobyte string
	 * 
	 * @param val long
	 * @return String
	 */
	public final static String asKilobyteString(long val) {
		
		//	Calculate the kilobyte value
		
		long mbVal = val / KILOBYTE;
		return "" + mbVal + "Kb";
	}

	/**
	 * Return a byte value as a megabyte string
	 * 
	 * @param val long
	 * @return String
	 */
	public final static String asMegabyteString(long val) {
		
		//	Calculate the megabyte value
		
		long mbVal = val / MEGABYTE;
		return "" + mbVal + "Mb";
	}

	/**
	 * Return a byte value as a gigabyte string
	 * 
	 * @param val long
	 * @return String
	 */
	public final static String asGigabyteString(long val) {
		
		//	Calculate the gigabyte value
		
		long mbVal = val / GIGABYTE;
		return "" + mbVal + "Gb";
	}

	/**
	 * Return a byte value as a terabyte string
	 * 
	 * @param val long
	 * @return String
	 */
	public final static String asTerabyteString(long val) {
		
		//	Calculate the terabyte value
		
		long mbVal = val / TERABYTE;
		return "" + mbVal + "Tb";
	}
	
	/**
	 * Return a byte value as a scaled string
	 * 
	 * @param val long
	 * @return String
	 */
	public final static String asScaledString(long val) {
		
		//	Determine the scaling to apply
		
		String ret = null;
		
		if ( val < (KILOBYTE * 2L))
		  ret = Long.toString(val); 
		else if ( val < (MEGABYTE * 2L))
			ret = asKilobyteString(val);
		else if ( val < (GIGABYTE * 2L))
			ret = asMegabyteString(val);
		else if ( val < (TERABYTE * 2L))
			ret = asGigabyteString(val);
		else
			ret = asTerabyteString(val);
			
		return ret;
	}
}