Base64.java

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/*
 * $Header: /cvs/javaserverfaces-sources/jsf-ri/systest/src/com/sun/faces/systest/render/Base64.java,v 1.2 2007/04/27 22:01:16 ofung Exp $
 * $Revision: 1.2 $
 * $Date: 2007/04/27 22:01:16 $
 * ====================================================================
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package com.sun.faces.systest.render;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;

/**
 * <p>Base64 encoder and decoder.</p>
 * <p/>
 * This class provides encoding/decoding methods for
 * the Base64 encoding 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
 * </p>
 *
 * @@author Jeffrey Rodriguez
 * @@version $Revision: 1.2 $ $Date: 2007/04/27 22:01:16 $
 */
public final class Base64 {

    static protected final String DEFAULT_CHAR_ENCODING = "ISO-8859-1";
    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 final byte[] EMPTY_BYTE_ARRAY = new byte[0];
    static private byte[] base64Alphabet = new byte[BASELENGTH];
    static private byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];


    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) '/';

    }

    //
    // Constructors and Initializers
    //
    private Base64() {

        throw new IllegalStateException();

    }


    public static boolean isBase64(String isValidString) {
        return (isBase64(isValidString.getBytes()));
    }


    public static boolean isBase64(byte octect) {
        // Should we ignore white space?
        return (octect == PAD || base64Alphabet[octect] != -1);
    }


    public static boolean isBase64(byte[] arrayOctect) {
        int length = arrayOctect.length;
        if (length == 0) {
            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 binaryData
     * @@return Base64-encoded array
     */
    public static byte[] encode(byte[] binaryData) {
        if (binaryData == null)
            binaryData = EMPTY_BYTE_ARRAY;

        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;
        for (i = 0; i < numberTriplets; i++) {

            dataIndex = i * 3;
            b1 = binaryData[dataIndex];
            b2 = binaryData[dataIndex + 1];
            b3 = binaryData[dataIndex + 2];

            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];
            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);
            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;
    }


    /**
     * Returns the base64 encoding of String.  First the String is
     * converted to byte[], using the character encoding of
     * <code>ISO-8859-1</code>.
     *
     * @@param data String of data to convert
     * @@return Base64-encoded String
     */
    public static String encode(String data) {
        try {
            return encode(data, DEFAULT_CHAR_ENCODING);
        } catch (UnsupportedEncodingException uee) {
            throw new IllegalStateException(uee.toString());
        }
    }


    /**
     * Returns the base64 encoding of String (by first converting to
     * byte[], using the specified <code>charEncoding</code>).  The
     * return value is also a String.  The Default
     * <code>codeEncoding</chode> is <code>ISO-8859-1</code>.
     *
     * @@param data String of data to convert
     * @@param charEncoding the character encoding to use when converting
     * a String to a byte[]
     * @@return Base64-encoded String
     */
    public static String encode(String data, String charEncoding)
        throws UnsupportedEncodingException {

        // Check arguments
        if (data == null)
            data = "";
        if (charEncoding == null)
            charEncoding = DEFAULT_CHAR_ENCODING;

        // Convert to byte[]
        ByteArrayOutputStream bos = new ByteArrayOutputStream();
        OutputStreamWriter osw = new OutputStreamWriter(bos, charEncoding);
        try {
            osw.write(data);
        } catch (IOException ioe) {
            throw new RuntimeException(ioe.toString());
        }

        // Encode
        byte[] encodedData = encode(bos.toByteArray());

        // Convert to String
        if (encodedData == null)
            return "";
        bos = new ByteArrayOutputStream(encodedData.length);
        try {
            bos.write(encodedData);
        } catch (IOException ioe) {
            throw new RuntimeException(ioe.toString());
        }

        return bos.toString(charEncoding);
    }


    /**
     * Decodes Base64 data into octects
     *
     * @@param binaryData Byte array containing Base64 data
     * @@return Array containing decoded data.
     */
    public static byte[] decode(byte[] base64Data) {
        // Should we throw away anything not in base64Data ?

        // handle the edge case, so we don't have to worry about it later
        if (base64Data.length == 0) {
            return EMPTY_BYTE_ARRAY;
        }

        int numberQuadruple = base64Data.length / FOURBYTE;
        byte decodedData[] = null;
        byte b1 = 0, b2 = 0, b3 = 0, b4 = 0, marker0 = 0, marker1 = 0;

        int encodedIndex = 0;
        int dataIndex = 0;
        {
            // this block sizes the output array properly - rlw
            int lastData = base64Data.length;
            // ignore the '=' padding
            while (base64Data[lastData - 1] == PAD) {
                if (--lastData == 0) {
                    return EMPTY_BYTE_ARRAY;
                }
            }
            decodedData = new byte[lastData - numberQuadruple];
        }

        for (int i = 0; i < numberQuadruple; i++) {
            dataIndex = i * 4;
            marker0 = base64Data[dataIndex + 2];
            marker1 = base64Data[dataIndex + 3];

            b1 = base64Alphabet[base64Data[dataIndex]];
            b2 = base64Alphabet[base64Data[dataIndex + 1]];

            if (marker0 != PAD && marker1 != PAD) {
                //No PAD e.g 3cQl
                b3 = base64Alphabet[marker0];
                b4 = base64Alphabet[marker1];

                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] =
                    (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
                decodedData[encodedIndex + 2] = (byte) (b3 << 6 | b4);
            } else if (marker0 == PAD) {
                //Two PAD e.g. 3c[Pad][Pad]
                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
            } else if (marker1 == PAD) {
                //One PAD e.g. 3cQ[Pad]
                b3 = base64Alphabet[marker0];

                decodedData[encodedIndex] = (byte) (b1 << 2 | b2 >> 4);
                decodedData[encodedIndex + 1] =
                    (byte) (((b2 & 0xf) << 4) | ((b3 >> 2) & 0xf));
            }
            encodedIndex += 3;
        }
        return decodedData;
    }

}