测试代码

package cn.java.codec.base64;public class Test {    public static void main(String[] args) {        String str = "hello world";        System.out.println("test Str : " + str);                byte[] binaryData = str.getBytes();        String encodeStr = Base64.encode(binaryData);        System.out.println("Base64.encode Result : " + encodeStr);                byte[] decodeBytes = Base64.decode(encodeStr);        String decodeStr = new String(decodeBytes);        System.out.println("Base64.decode Result : " + decodeStr);    }}

 

输出结果

test Str : hello worldBase64.encode Result : aGVsbG8gd29ybGQ=Base64.decode Result : hello world

 

工具代码

 

package cn.java.codec.base64;public final class Base64 {    private static final int BASELENGTH = 128;    private static final int LOOKUPLENGTH = 64;    private static final int TWENTYFOURBITGROUP = 24;    private static final int EIGHTBIT = 8;    private static final int SIXTEENBIT = 16;    private static final int FOURBYTE = 4;    private static final int SIGN = -128;    private static char PAD = '=';    private static byte[] base64Alphabet = new byte[BASELENGTH];    private static char[] lookUpBase64Alphabet = new char[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] = (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) '/';    }    private static boolean isWhiteSpace(char octect) {        return (octect == 0x20 || octect == 0xd || octect == 0xa || octect == 0x9);    }    private static boolean isPad(char octect) {        return (octect == PAD);    }    private static boolean isData(char octect) {        return (octect < BASELENGTH && base64Alphabet[octect] != -1);    }    /**     * Encodes hex octects into Base64     *      * @param binaryData     *            Array containing binaryData     * @return Encoded Base64 array     */    public static String encode(byte[] binaryData) {        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;        for (int i = 0; i < numberTriplets; i++) {            b1 = binaryData[dataIndex++];            b2 = binaryData[dataIndex++];            b3 = binaryData[dataIndex++];            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);            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);                        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);    }    /**     * Decodes Base64 data into octects     *      * @param encoded     *            string containing Base64 data     * @return Array containind decoded data.     */    public static byte[] decode(String encoded) {        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)) {                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)) {                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;            }        } 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;    }    /**     * remove WhiteSpace from MIME containing encoded Base64 data.     *      * @param data     *            the byte array of base64 data (with WS)     * @return the new length     */    private static int removeWhiteSpace(char[] data) {        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;    }}