src/main/java/org/openflow/util/HexString.java

/**
*    Copyright (c) 2008 The Board of Trustees of The Leland Stanford Junior
*    University
* 
*    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 org.openflow.util;

import java.math.BigInteger;

public class HexString {
    /**
     * Convert a string of bytes to a ':' separated hex string
     * @param bytes
     * @return "0f:ca:fe:de:ad:be:ef"
     */
    public static String toHexString(byte[] bytes) {
        int i;
        String ret = "";
        String tmp;
        for(i=0; i< bytes.length; i++) {
            if(i> 0)
                ret += ":";
            tmp = Integer.toHexString(U8.f(bytes[i]));
            if (tmp.length() == 1)
                ret += "0";
            ret += tmp; 
        }
        return ret;
    }
    
    public static String toHexString(long val, int padTo) {
        char arr[] = Long.toHexString(val).toCharArray();
        String ret = "";
        // prepend the right number of leading zeros
        int i = 0;
        for (; i < (padTo * 2 - arr.length); i++) {
            ret += "0";
            if ((i % 2) == 1)
                ret += ":";
        }
        for (int j = 0; j < arr.length; j++) {
            ret += arr[j];
            if ((((i + j) % 2) == 1) && (j < (arr.length - 1)))
                ret += ":";
        }
        return ret;        
    }
   
    public static String toHexString(long val) {
        return toHexString(val, 8);
    }
    
    
    /**
     * Convert a string of hex values into a string of bytes
     * @param values "0f:ca:fe:de:ad:be:ef"
     * @return [15, 5 ,2, 5, 17] 
     * @throws NumberFormatException If the string can not be parsed
     */ 
    public static byte[] fromHexString(String values) throws NumberFormatException {
        String[] octets = values.split(":");
        byte[] ret = new byte[octets.length];
        
        for(int i = 0; i < octets.length; i++) {
            if (octets[i].length() > 2)
                throw new NumberFormatException("Invalid octet length");
            ret[i] = Integer.valueOf(octets[i], 16).byteValue();
        }
        return ret;
    }
    
    public static long toLong(String values) throws NumberFormatException {
        // Long.parseLong() can't handle HexStrings with MSB set. Sigh. 
        BigInteger bi = new BigInteger(values.replaceAll(":", ""),16);
        if (bi.bitLength() > 64) 
            throw new NumberFormatException("Input string too big to fit in long: " + values);
        return bi.longValue();
    }

}