public final class AbBase64 {        /** The Constant base64EncodeChars. */    private static final char[] base64EncodeChars = new char[] {‘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‘, ‘+‘, ‘/‘};        /** The Constant base64DecodeChars. */    private static final byte[] base64DecodeChars = new byte[] {-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, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1,            -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20,            21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,            39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1};        /**     * Encode.     *     * @param str the str     * @param charsetName the charset name     * @return the string     */    public static final String encode(String str, String charsetName) {        return encode(str, charsetName, 0);    }        /**     * Encode.     *     * @param str the str     * @param charsetName the charset name     * @param width the width     * @return the string     */    public static final String encode(String str, String charsetName, int width) {        byte[] data = http://www.mamicode.com/null;        try {            data = str.getBytes(charsetName);        } catch (UnsupportedEncodingException e) {            e.printStackTrace();            return null;        }        int length = data.length;        int size = (int) Math.ceil(length * 1.36);        int splitsize = width > 0 ? size / width : 0;        StringBuffer sb = new StringBuffer(size + splitsize);        int r = length % 3;        int len = length - r;        int i = 0;        int c;        while (i < len) {            c = (0x000000ff & data[i++]) << 16 | (0x000000ff & data[i++]) << 8 | (0x000000ff & data[i++]);            sb.append(base64EncodeChars[c >> 18]);            sb.append(base64EncodeChars[c >> 12 & 0x3f]);            sb.append(base64EncodeChars[c >> 6 & 0x3f]);            sb.append(base64EncodeChars[c & 0x3f]);        }        if (r == 1) {            c = 0x000000ff & data[i++];            sb.append(base64EncodeChars[c >> 2]);            sb.append(base64EncodeChars[(c & 0x03) << 4]);            sb.append("==");        } else if (r == 2) {            c = (0x000000ff & data[i++]) << 8 | (0x000000ff & data[i++]);            sb.append(base64EncodeChars[c >> 10]);            sb.append(base64EncodeChars[c >> 4 & 0x3f]);            sb.append(base64EncodeChars[(c & 0x0f) << 2]);            sb.append("=");        }        if (splitsize > 0) {            char split = ‘\n‘;            for (i = width; i < sb.length(); i++) {                sb.insert(i, split);                i += width;            }        }        return sb.toString();    }        /**     * Decode.     *     * @param str the str     * @param charsetName the charset name     * @return the string     */    public static final String decode(String str, String charsetName) {        byte[] data = http://www.mamicode.com/null;        try {            data = str.getBytes(charsetName);        } catch (UnsupportedEncodingException e) {            e.printStackTrace();            return null;        }        int len = data.length;        ByteArrayOutputStream buf = new ByteArrayOutputStream((int) (len * 0.67));        int i = 0;        int b1, b2, b3, b4;        while (i < len) {            do {                if (i >= len) {                    b1 = -1;                    break;                }                b1 = base64DecodeChars[data[i++]];            } while (i < len && b1 == -1);            if (b1 == -1) {                break;            }            do {                if (i >= len) {                    b2 = -1;                    break;                }                b2 = base64DecodeChars[data[i++]];            } while (i < len && b2 == -1);            if (b2 == -1) {                break;            }            buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));            do {                if (i >= len) {                    b3 = -1;                    break;                }                b3 = data[i++];                if (b3 == 61) {                    b3 = -1;                    break;                }                b3 = base64DecodeChars[b3];            } while (i < len && b3 == -1);            if (b3 == -1) {                break;            }            buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));            do {                if (i >= len) {                    b4 = -1;                    break;                }                b4 = data[i++];                if (b4 == 61) {                    b4 = -1;                    break;                }                b4 = base64DecodeChars[b4];            } while (b4 == -1);            if (b4 == -1) {                break;            }            buf.write((int) (((b3 & 0x03) << 6) | b4));        }        try {            return buf.toString(charsetName);        } catch (UnsupportedEncodingException e) {            e.printStackTrace();            return null;        }    }}