Java Tutorial/Development/Base64

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Base64 encoding/decoding.

/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
 * License Header, with the fields enclosed by brackets [] replaced by
 * your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
 *
 * Contributor(s):
 *
 * The Original Software is NetBeans. The Initial Developer of the Original
 * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
 * Microsystems, Inc. All Rights Reserved.
 *
 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
 * single choice of license, a recipient has the option to distribute
 * your version of this file under either the CDDL, the GPL Version 2 or
 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
 * Version 2 license, then the option applies only if the new code is
 * made subject to such option by the copyright holder.
 */
/** This class provides Base64 encoding/decoding.
 */
public class Base64
{
    private Base64()
    {
        //Avoid instantiation of this class
    }
    
    /** Encodes datas using base64 encoding.
     * @param abyte0 data for encoding
     * @return encoded string
     */
    static String encode(final byte abyte0[])
    {
        final StringBuffer stringbuffer = new StringBuffer();
        for(int i = 0; i < abyte0.length; i += 3)
            stringbuffer.append(encodeBlock(abyte0, i));
        
        return stringbuffer.toString();
    }
    
    private static char[] encodeBlock(final byte abyte0[], final int i)
    {
        int j = 0;
        final int k = abyte0.length - i - 1;
        final int l = k < 2 ? k : 2;
        for(int i1 = 0; i1 <= l; i1++)
        {
            final byte byte0 = abyte0[i + i1];
            final int j1 = byte0 >= 0 ? ((int) (byte0)) : byte0 + 256;
            j += j1 << 8 * (2 - i1);
        }
        
        char ac[] = new char[4];
        for(int k1 = 0; k1 < 4; k1++)
        {
            final int l1 = j >>> 6 * (3 - k1) & 0x3f;
            ac[k1] = getChar(l1);
        }
        
        if(k < 1)
            ac[2] = "=";
        if(k < 2)
            ac[3] = "=";
        return ac;
    }
    
    private static char getChar(final int i)
    {
        if(i >= 0 && i <= 25)
            return (char)(65 + i);
        if(i >= 26 && i <= 51)
            return (char)(97 + (i - 26));
        if(i >= 52 && i <= 61)
            return (char)(48 + (i - 52));
        if(i == 62)
            return "+";
        return i != 63 ? "?" : "/";
    }
    
    /** Decode string using Base64 encoding.
     * @param s string for decoding
     * @return decoded data
     */
    static byte[] decode(final String s)
    {
        if (s.length() == 0) return new byte[0];
        int i = 0;
        for(int j = s.length() - 1; j > 0 && s.charAt(j) == "="; j--)
            i++;
        
        final int k = (s.length() * 6) / 8 - i;
        byte abyte0[] = new byte[k];
        int l = 0;
        for(int i1 = 0; i1 < s.length(); i1 += 4)
        {
            final int j1 = (getValue(s.charAt(i1)) << 18) + (getValue(s.charAt(i1 + 1)) << 12) + (getValue(s.charAt(i1 + 2)) << 6) + getValue(s.charAt(i1 + 3));
            for(int k1 = 0; k1 < 3 && l + k1 < abyte0.length; k1++)
                abyte0[l + k1] = (byte)(j1 >> 8 * (2 - k1) & 0xff);
            
            l += 3;
        }
        return abyte0;
    }
    
    private static int getValue(final char c)
    {
        if(c >= "A" && c <= "Z")
            return c - 65;
        if(c >= "a" && c <= "z")
            return (c - 97) + 26;
        if(c >= "0" && c <= "9")
            return (c - 48) + 52;
        if(c == "+")
            return 62;
        if(c == "/")
            return 63;
        return c != "=" ? -1 : 0;
    }
}





Encode/decode for RFC ase64 as defined by RFC 2045

/*
 * 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.
 */

/**
 * This class provides encode/decode for RFC 2045 Base64 as defined by
 * RFC 2045, N. Freed and N. Borenstein.  :
 * Multipurpose Internet Mail Extensions (MIME) Part One: Format of
 * Internet Message Bodies. Reference 1996
 *
 * @author Jeffrey Rodriguez
 * @version $Id: Base64.java 515 2008-03-17 21:02:23Z jfrederic.clere@jboss.ru $
 */
public final class  Base64
{
    static private final int  BASELENGTH         = 255;
    static private final int  LOOKUPLENGTH       = 64;
    static private final int  TWENTYFOURBITGROUP = 24;
    static private final int  EIGHTBIT           = 8;
    static private final int  SIXTEENBIT         = 16;
    static private final int  SIXBIT             = 6;
    static private final int  FOURBYTE           = 4;
    static private final int  SIGN               = -128;
    static private final byte PAD                = (byte) "=";
    static private byte [] base64Alphabet       = new byte[BASELENGTH];
    static private byte [] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];
    //static private final Log log = LogSource.getInstance("org.apache.rumons.util.Base64");
    static
    {
        for (int i = 0; i < BASELENGTH; i++ )
        {
            base64Alphabet[i] = -1;
        }
        for (int i = "Z"; i >= "A"; i--)
        {
            base64Alphabet[i] = (byte) (i - "A");
        }
        for (int i = "z"; i>= "a"; i--)
        {
            base64Alphabet[i] = (byte) (i - "a" + 26);
        }
        for (int i = "9"; i >= "0"; i--)
        {
            base64Alphabet[i] = (byte) (i - "0" + 52);
        }
        base64Alphabet["+"]  = 62;
        base64Alphabet["/"]  = 63;
        for (int i = 0; i <= 25; i++ )
            lookUpBase64Alphabet[i] = (byte) ("A" + i);
        for (int i = 26,  j = 0; i <= 51; i++, j++ )
            lookUpBase64Alphabet[i] = (byte) ("a"+ j);
        for (int i = 52,  j = 0; i <= 61; i++, j++ )
            lookUpBase64Alphabet[i] = (byte) ("0" + j);
        lookUpBase64Alphabet[62] = (byte) "+";
        lookUpBase64Alphabet[63] = (byte) "/";
    }
    public static boolean isBase64( String isValidString )
    {
        return isArrayByteBase64(isValidString.getBytes());
    }
    public static boolean isBase64( byte octect )
    {
        //shall we ignore white space? JEFF??
        return (octect == PAD || base64Alphabet[octect] != -1);
    }
    public static boolean isArrayByteBase64( byte[] arrayOctect )
    {
        int length = arrayOctect.length;
        if (length == 0)
        {
            // shouldn"t a 0 length array be valid base64 data?
            // return false;
            return true;
        }
        for (int i=0; i < length; i++)
        {
            if ( !Base64.isBase64(arrayOctect[i]) )
                return false;
        }
        return true;
    }
    /**
     * Encodes hex octects into Base64.
     *
     * @param binaryData Array containing binary data to encode.
     * @return Base64-encoded data.
     */
    public static byte[] encode( byte[] binaryData )
    {
        int      lengthDataBits    = binaryData.length*EIGHTBIT;
        int      fewerThan24bits   = lengthDataBits%TWENTYFOURBITGROUP;
        int      numberTriplets    = lengthDataBits/TWENTYFOURBITGROUP;
        byte     encodedData[]     = null;

        if (fewerThan24bits != 0)
        {
            //data not divisible by 24 bit
            encodedData = new byte[ (numberTriplets + 1 ) * 4 ];
        }
        else
        {
            // 16 or 8 bit
            encodedData = new byte[ numberTriplets * 4 ];
        }
        byte k = 0, l = 0, b1 = 0, b2 = 0, b3 = 0;
        int encodedIndex = 0;
        int dataIndex   = 0;
        int i           = 0;
        //log.debug("number of triplets = " + numberTriplets);
        for ( i = 0; i<numberTriplets; i++ )
        {
            dataIndex = i*3;
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            b3 = binaryData[dataIndex + 2];
            //log.debug("b1= " + b1 +", b2= " + b2 + ", b3= " + b3);
            l  = (byte)(b2 & 0x0f);
            k  = (byte)(b1 & 0x03);
            encodedIndex = i * 4;
            byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
            byte val2 = ((b2 & SIGN)==0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
            byte val3 = ((b3 & SIGN)==0)?(byte)(b3>>6):(byte)((b3)>>6^0xfc);
            encodedData[encodedIndex]   = lookUpBase64Alphabet[ val1 ];
            //log.debug( "val2 = " + val2 );
            //log.debug( "k4   = " + (k<<4) );
            //log.debug(  "vak  = " + (val2 | (k<<4)) );
            encodedData[encodedIndex+1] =
                lookUpBase64Alphabet[ val2 | ( k<<4 )];
            encodedData[encodedIndex+2] =
                lookUpBase64Alphabet[ (l <<2 ) | val3 ];
            encodedData[encodedIndex+3] = lookUpBase64Alphabet[ b3 & 0x3f ];
        }
        // form integral number of 6-bit groups
        dataIndex    = i*3;
        encodedIndex = i*4;
        if (fewerThan24bits == EIGHTBIT )
        {
            b1 = binaryData[dataIndex];
            k = (byte) ( b1 &0x03 );
            //log.debug("b1=" + b1);
            //log.debug("b1<<2 = " + (b1>>2) );
            byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
            encodedData[encodedIndex]     = lookUpBase64Alphabet[ val1 ];
            encodedData[encodedIndex + 1] = lookUpBase64Alphabet[ k<<4 ];
            encodedData[encodedIndex + 2] = PAD;
            encodedData[encodedIndex + 3] = PAD;
        }
        else if (fewerThan24bits == SIXTEENBIT)
        {
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex +1 ];
            l = (byte) (b2 & 0x0f);
            k = (byte) (b1 & 0x03);
            byte val1 = ((b1 & SIGN) == 0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
            byte val2 = ((b2 & SIGN) == 0)?(byte)(b2>>4):(byte)((b2)>>4^0xf0);
            encodedData[encodedIndex]     = lookUpBase64Alphabet[ val1 ];
            encodedData[encodedIndex + 1] =
                lookUpBase64Alphabet[ val2 | ( k<<4 )];
            encodedData[encodedIndex + 2] = lookUpBase64Alphabet[ l<<2 ];
            encodedData[encodedIndex + 3] = PAD;
        }
        return encodedData;
    }

}





to Base64

/****************************************************************
 * 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.                                           *
 ****************************************************************/

public class EncodeUtils {
    
    public static final int MASK = 0x3F;
    public static final int FIRST_MASK = MASK << 18; 
    public static final int SECOND_MASK = MASK << 12; 
    public static final int THIRD_MASK = MASK << 6; 
    public static final int FORTH_MASK = MASK; 
    
    public static final byte[] ENCODING = {"A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N",
        "O", "P" ,"Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z", "a", "b", "c", "d", "e", "f", "g", "h", "i",
        "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z", "0", "1", "2", "3",
        "4", "5", "6", "7", "8", "9", "+", "/"};
    
    public static final void main(String[] args) throws Exception {
        byte[] bytes = {(byte) 0, (byte) 128, (byte) 0};
        System.out.println(new String(toBase64(bytes)));
        System.out.println(new String(toBase64("Hello, World".getBytes())));
        System.out.println(new String(toBase64("Monday".getBytes())));
        System.out.println(new String(toBase64("M\u00F6nchengladbach\r\n".getBytes("ISO-8859-1"))));
    }
    
    public static byte[] toBase64(byte[] in) {
        int inputLength = in.length;
        int outputLength = (int) Math.floor((4*inputLength) / 3f) + 3;
        outputLength = outputLength + 2 * (int) Math.floor(outputLength / 76f);
        byte[] results = new byte[outputLength];
        int inputIndex = 0;
        int outputIndex = 0;
        while (inputLength - inputIndex > 2) {
            int one = (toInt(in[inputIndex++]) << 16);
            int two = (toInt(in[inputIndex++]) << 8);
            int three = toInt(in[inputIndex++]);
            int quantum = one | two | three;
            int index = (quantum & FIRST_MASK) >> 18;
            outputIndex = setResult(results, outputIndex, ENCODING[index]);
            index = (quantum & SECOND_MASK) >> 12;
            outputIndex = setResult(results, outputIndex, ENCODING[index]);
            index = (quantum & THIRD_MASK) >> 6;
            outputIndex = setResult(results, outputIndex, ENCODING[index]);
            index = (quantum & FORTH_MASK);
            outputIndex = setResult(results, outputIndex, ENCODING[index]);
        }
        
        switch (inputLength - inputIndex) {
            case 1:
                int quantum = in[inputIndex++] << 16;
                int index = (quantum & FIRST_MASK) >> 18;
                outputIndex = setResult(results, outputIndex, ENCODING[index]);
                index = (quantum & SECOND_MASK) >> 12;
                outputIndex = setResult(results, outputIndex, ENCODING[index]);
                outputIndex = setResult(results, outputIndex, (byte) "=");
                outputIndex = setResult(results, outputIndex, (byte) "=");
                break;
                
            case 2:
                quantum = (in[inputIndex++] << 16) + (in[inputIndex++] << 8);
                index = (quantum & FIRST_MASK) >> 18;
                outputIndex = setResult(results, outputIndex, ENCODING[index]);
                index = (quantum & SECOND_MASK) >> 12;
                outputIndex = setResult(results, outputIndex, ENCODING[index]);
                index = (quantum & THIRD_MASK) >> 6;
                outputIndex = setResult(results, outputIndex, ENCODING[index]);
                outputIndex = setResult(results, outputIndex, (byte) "=");
                break;
        }
        
        return results;
    }
    private static int toInt(byte b) {
        return 255 & b;
    }

    private static int setResult(byte[] results, int outputIndex, byte value) {
        results[outputIndex++] = value;
        outputIndex = checkLineLength(results, outputIndex);
        return outputIndex;
    }

    private static int checkLineLength(byte[] results, int outputIndex) {
        if (outputIndex == 76 || outputIndex > 76 && (outputIndex - 2*Math.floor(outputIndex/76f - 1)) % 76 == 0) {
            results[outputIndex++] = "\r";
            results[outputIndex++] = "\n";
        }
        return outputIndex;
    }
}