base64.java

一个比较好的jsf spring hibernate的例子

        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;
    }

}