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Base64.javaAPI DocApache Xerces 3.0.111398Fri Sep 14 20:33:54 BST 2007org.apache.xerces.impl.dv.util

Base64

public final class Base64 extends Object
This class provides encode/decode for RFC 2045 Base64 as defined by RFC 2045, N. Freed and N. Borenstein. RFC 2045: Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies. Reference 1996 Available at: http://www.ietf.org/rfc/rfc2045.txt This class is used by XML Schema binary format validation This implementation does not encode/decode streaming data. You need the data that you will encode/decode already on a byte arrray.
xerces.internal
author
Jeffrey Rodriguez
author
Sandy Gao
version
$Id: Base64.java 446747 2006-09-15 21:46:20Z mrglavas $

Fields Summary
private static final int
BASELENGTH
private static final int
LOOKUPLENGTH
private static final int
TWENTYFOURBITGROUP
private static final int
EIGHTBIT
private static final int
SIXTEENBIT
private static final int
SIXBIT
private static final int
FOURBYTE
private static final int
SIGN
private static final char
PAD
private static final boolean
fDebug
private static final byte[]
base64Alphabet
private static final char[]
lookUpBase64Alphabet
Constructors Summary
Methods Summary
public static byte[]decode(java.lang.String encoded)
Decodes Base64 data into octects

param
encoded string containing Base64 data
return
Array containind decoded data.


        if (encoded == null)
            return null;

        char[] base64Data = encoded.toCharArray();
        // remove white spaces
        int len = removeWhiteSpace(base64Data);
        
        if (len%FOURBYTE != 0) {
            return null;//should be divisible by four
        }

        int      numberQuadruple    = (len/FOURBYTE );

        if (numberQuadruple == 0)
            return new byte[0];

        byte     decodedData[]      = null;
        byte     b1=0,b2=0,b3=0,b4=0;
        char     d1=0,d2=0,d3=0,d4=0;

        int i = 0;
        int encodedIndex = 0;
        int dataIndex    = 0;
        decodedData      = new byte[ (numberQuadruple)*3];

        for (; i<numberQuadruple-1; i++) {

            if (!isData( (d1 = base64Data[dataIndex++]) )||
                !isData( (d2 = base64Data[dataIndex++]) )||
                !isData( (d3 = base64Data[dataIndex++]) )||
                !isData( (d4 = base64Data[dataIndex++]) ))
                return null;//if found "no data" just return null

            b1 = base64Alphabet[d1];
            b2 = base64Alphabet[d2];
            b3 = base64Alphabet[d3];
            b4 = base64Alphabet[d4];

            decodedData[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 ) ;
            decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
            decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );
        }

        if (!isData( (d1 = base64Data[dataIndex++]) ) ||
            !isData( (d2 = base64Data[dataIndex++]) )) {
            return null;//if found "no data" just return null
        }

        b1 = base64Alphabet[d1];
        b2 = base64Alphabet[d2];

        d3 = base64Data[dataIndex++];
        d4 = base64Data[dataIndex++];
        if (!isData( (d3 ) ) ||
            !isData( (d4 ) )) {//Check if they are PAD characters
            if (isPad( d3 ) && isPad( d4)) {               //Two PAD e.g. 3c[Pad][Pad]
                if ((b2 & 0xf) != 0)//last 4 bits should be zero
                    return null;
                byte[] tmp = new byte[ i*3 + 1 ];
                System.arraycopy( decodedData, 0, tmp, 0, i*3 );
                tmp[encodedIndex]   = (byte)(  b1 <<2 | b2>>4 ) ;
                return tmp;
            } else if (!isPad( d3) && isPad(d4)) {               //One PAD  e.g. 3cQ[Pad]
                b3 = base64Alphabet[ d3 ];
                if ((b3 & 0x3 ) != 0)//last 2 bits should be zero
                    return null;
                byte[] tmp = new byte[ i*3 + 2 ];
                System.arraycopy( decodedData, 0, tmp, 0, i*3 );
                tmp[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 );
                tmp[encodedIndex]   = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
                return tmp;
            } else {
                return null;//an error  like "3c[Pad]r", "3cdX", "3cXd", "3cXX" where X is non data
            }
        } else { //No PAD e.g 3cQl
            b3 = base64Alphabet[ d3 ];
            b4 = base64Alphabet[ d4 ];
            decodedData[encodedIndex++] = (byte)(  b1 <<2 | b2>>4 ) ;
            decodedData[encodedIndex++] = (byte)(((b2 & 0xf)<<4 ) |( (b3>>2) & 0xf) );
            decodedData[encodedIndex++] = (byte)( b3<<6 | b4 );

        }

        return decodedData;
public static java.lang.Stringencode(byte[] binaryData)
Encodes hex octects into Base64

param
binaryData Array containing binaryData
return
Encoded Base64 array


        if (binaryData == null)
            return null;

        int      lengthDataBits    = binaryData.length*EIGHTBIT;
        if (lengthDataBits == 0) {
            return "";
        }
        
        int      fewerThan24bits   = lengthDataBits%TWENTYFOURBITGROUP;
        int      numberTriplets    = lengthDataBits/TWENTYFOURBITGROUP;
        int      numberQuartet     = fewerThan24bits != 0 ? numberTriplets+1 : numberTriplets;
        char     encodedData[]     = null;

        encodedData = new char[numberQuartet*4];

        byte k=0, l=0, b1=0,b2=0,b3=0;

        int encodedIndex = 0;
        int dataIndex   = 0;
        if (fDebug) {
            System.out.println("number of triplets = " + numberTriplets );
        }

        for (int i=0; i<numberTriplets; i++) {
            b1 = binaryData[dataIndex++];
            b2 = binaryData[dataIndex++];
            b3 = binaryData[dataIndex++];

            if (fDebug) {
                System.out.println( "b1= " + b1 +", b2= " + b2 + ", b3= " + b3 );
            }

            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);
            byte val3 = ((b3 & SIGN)==0)?(byte)(b3>>6):(byte)((b3)>>6^0xfc);

            if (fDebug) {
                System.out.println( "val2 = " + val2 );
                System.out.println( "k4   = " + (k<<4));
                System.out.println( "vak  = " + (val2 | (k<<4)));
            }

            encodedData[encodedIndex++] = lookUpBase64Alphabet[ val1 ];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ val2 | ( k<<4 )];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ (l <<2 ) | val3 ];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ b3 & 0x3f ];
        }

        // form integral number of 6-bit groups
        if (fewerThan24bits == EIGHTBIT) {
            b1 = binaryData[dataIndex];
            k = (byte) ( b1 &0x03 );
            if (fDebug) {
                System.out.println("b1=" + b1);
                System.out.println("b1<<2 = " + (b1>>2) );
            }
            byte val1 = ((b1 & SIGN)==0)?(byte)(b1>>2):(byte)((b1)>>2^0xc0);
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ val1 ];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ k<<4 ];
            encodedData[encodedIndex++] = PAD;
            encodedData[encodedIndex++] = 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++] = lookUpBase64Alphabet[ val2 | ( k<<4 )];
            encodedData[encodedIndex++] = lookUpBase64Alphabet[ l<<2 ];
            encodedData[encodedIndex++] = PAD;
        }

        return new String(encodedData);
protected static booleanisBase64(char octect)

        return (isWhiteSpace(octect) || isPad(octect) || isData(octect));
protected static booleanisData(char octect)

        return (octect < BASELENGTH && base64Alphabet[octect] != -1);
protected static booleanisPad(char octect)

        return (octect == PAD);
protected static booleanisWhiteSpace(char octect)


     

        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] = (char)('A"+i);

        for (int i = 26,  j = 0; i<=51; i++, j++)
            lookUpBase64Alphabet[i] = (char)('a"+ j);

        for (int i = 52,  j = 0; i<=61; i++, j++)
            lookUpBase64Alphabet[i] = (char)('0" + j);
        lookUpBase64Alphabet[62] = (char)'+";
        lookUpBase64Alphabet[63] = (char)'/";

    
        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);
protected static intremoveWhiteSpace(char[] data)
remove WhiteSpace from MIME containing encoded Base64 data.

param
data the byte array of base64 data (with WS)
return
the new length

        if (data == null)
            return 0;

        // count characters that's not whitespace
        int newSize = 0;
        int len = data.length;
        for (int i = 0; i < len; i++) {
            if (!isWhiteSpace(data[i]))
                data[newSize++] = data[i];
        }
        return newSize;