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Tomcat example source code file (HexUtils.java)

This example Tomcat source code file (HexUtils.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

a, a, bytearrayoutputstream, bytearrayoutputstream, dec, dec, f, hex, hexutils, illegalargumentexception, illegalargumentexception, io, string, stringbuffer, stringmanager

The Tomcat HexUtils.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.apache.tomcat.util.buf;

import java.io.ByteArrayOutputStream;
import org.apache.tomcat.util.res.StringManager;

/**
 * Library of utility methods useful in dealing with converting byte arrays
 * to and from strings of hexadecimal digits.
 * Code from Ajp11, from Apache's JServ.
 *
 * @author Craig R. McClanahan
 */

public final class HexUtils {


    // -------------------------------------------------------------- Constants


    /**
     *  Table for HEX to DEC byte translation.
     */
    public static final int[] DEC = {
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        00, 01, 02, 03, 04, 05, 06, 07,  8,  9, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
        -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
    };


    /**
     * Table for DEC to HEX byte translation.
     */
    public static final byte[] HEX = 
    { (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4', (byte) '5', 
      (byte) '6', (byte) '7', (byte) '8', (byte) '9', (byte) 'a', (byte) 'b', 
      (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f' };


    /**
     * The string manager for this package.
     */
    private static StringManager sm =
	StringManager.getManager("org.apache.tomcat.util.buf.res");


    // --------------------------------------------------------- Static Methods


    /**
     * Convert a String of hexadecimal digits into the corresponding
     * byte array by encoding each two hexadecimal digits as a byte.
     *
     * @param digits Hexadecimal digits representation
     *
     * @exception IllegalArgumentException if an invalid hexadecimal digit
     *  is found, or the input string contains an odd number of hexadecimal
     *  digits
     */
    public static byte[] convert(String digits) {

	ByteArrayOutputStream baos = new ByteArrayOutputStream();
	for (int i = 0; i < digits.length(); i += 2) {
	    char c1 = digits.charAt(i);
	    if ((i+1) >= digits.length())
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.odd"));
	    char c2 = digits.charAt(i + 1);
	    byte b = 0;
	    if ((c1 >= '0') && (c1 <= '9'))
		b += ((c1 - '0') * 16);
	    else if ((c1 >= 'a') && (c1 <= 'f'))
		b += ((c1 - 'a' + 10) * 16);
	    else if ((c1 >= 'A') && (c1 <= 'F'))
		b += ((c1 - 'A' + 10) * 16);
	    else
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.bad"));
	    if ((c2 >= '0') && (c2 <= '9'))
		b += (c2 - '0');
	    else if ((c2 >= 'a') && (c2 <= 'f'))
		b += (c2 - 'a' + 10);
	    else if ((c2 >= 'A') && (c2 <= 'F'))
		b += (c2 - 'A' + 10);
	    else
		throw new IllegalArgumentException
		    (sm.getString("hexUtil.bad"));
	    baos.write(b);
	}
	return (baos.toByteArray());

    }


    /**
     * Convert a byte array into a printable format containing a
     * String of hexadecimal digit characters (two per byte).
     *
     * @param bytes Byte array representation
     */
    public static String convert(byte bytes[]) {

	StringBuffer sb = new StringBuffer(bytes.length * 2);
	for (int i = 0; i < bytes.length; i++) {
	    sb.append(convertDigit((int) (bytes[i] >> 4)));
	    sb.append(convertDigit((int) (bytes[i] & 0x0f)));
	}
	return (sb.toString());

    }

    /**
     * Convert 4 hex digits to an int, and return the number of converted
     * bytes.
     *
     * @param hex Byte array containing exactly four hexadecimal digits
     *
     * @exception IllegalArgumentException if an invalid hexadecimal digit
     *  is included
     */
    public static int convert2Int( byte[] hex ) {
	// Code from Ajp11, from Apache's JServ
    
	// assert b.length==4
	// assert valid data
	int len;
	if(hex.length < 4 ) return 0;
	if( DEC[hex[0]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len = DEC[hex[0]];
	len = len << 4;
	if( DEC[hex[1]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[1]];
	len = len << 4;
	if( DEC[hex[2]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[2]];
	len = len << 4;
	if( DEC[hex[3]]<0 )
	    throw new IllegalArgumentException(sm.getString("hexUtil.bad"));
	len += DEC[hex[3]];
	return len;
    }



    /**
     * [Private] Convert the specified value (0 .. 15) to the corresponding
     * hexadecimal digit.
     *
     * @param value Value to be converted
     */
    private static char convertDigit(int value) {

	value &= 0x0f;
	if (value >= 10)
	    return ((char) (value - 10 + 'a'));
	else
	    return ((char) (value + '0'));

    }


}

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