SIUtils.java

/*******************************************************************************
 * This file is part of OpenNMS(R).
 *
 * Copyright (C) 2007-2011 The OpenNMS Group, Inc.
 * OpenNMS(R) is Copyright (C) 1999-2011 The OpenNMS Group, Inc.
 *
 * OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.
 *
 * OpenNMS(R) 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.
 *
 * OpenNMS(R) 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 OpenNMS(R).  If not, see:
 *      http://www.gnu.org/licenses/
 *
 * For more information contact:
 *     OpenNMS(R) Licensing <license@opennms.org>
 *     http://www.opennms.org/
 *     http://www.opennms.com/
 *******************************************************************************/

package org.opennms.core.utils;

import java.text.DecimalFormat;

/**
 * Utilities for manipulating values in SI units.  This is the
 * International System of Units that you learned in science class.
 *
 * @author djgregor
 * @link http://www.physics.nist.gov/cuu/Units/
 */
public abstract class SIUtils {
    /**
     * Always print at least one digit after the decimal point,
     * and at most three digits after the decimal point.
     */
    private static final DecimalFormat s_oneDigitAfterDecimal = new DecimalFormat("0.0##");
    
    /**
     * Print no digits after the decimal point (heh, nor a decimal point).
     */
    private static final DecimalFormat s_noDigitsAfterDecimal = new DecimalFormat("0");
    
    /**
     * Method used to convert an integer bits-per-second value to a more
     * readable vale using commonly recognized abbreviation for network
     * interface speeds. Feel free to expand it as necessary to accomodate
     * different values.
     *
     * @param ifSpeed
     *            The bits-per-second value to be converted into a string
     *            description
     * @return A string representation of the speed ("100 Mbps" for
     *         example)
     */
    public static String getHumanReadableIfSpeed(long ifSpeed) {
        DecimalFormat formatter;
        double displaySpeed;
        String units;
        
        if (ifSpeed >= 1000000000L) {
            if ((ifSpeed % 1000000000L) == 0) {
                formatter = s_noDigitsAfterDecimal;
            } else {
                formatter = s_oneDigitAfterDecimal;
            }
            displaySpeed = ((double) ifSpeed) / 1000000000;
            units = "Gbps";
        } else if (ifSpeed >= 1000000L) {
            if ((ifSpeed % 1000000L) == 0) {
                formatter = s_noDigitsAfterDecimal;
            } else {
                formatter = s_oneDigitAfterDecimal;
            }
            displaySpeed = ((double) ifSpeed) / 1000000;
            units = "Mbps";
        } else if (ifSpeed >= 1000L) {
            if ((ifSpeed % 1000L) == 0) {
                formatter = s_noDigitsAfterDecimal;
            } else {
                formatter = s_oneDigitAfterDecimal;
            }
            displaySpeed = ((double) ifSpeed) / 1000;
            units = "kbps";
        } else {
            formatter = s_noDigitsAfterDecimal;
            displaySpeed = (double) ifSpeed;
            units = "bps";
        }
        
        return formatter.format(displaySpeed) + " " + units;
    }
}