Class Base64

core/api/main/java/org/directwebremoting/util/Base64.java:78–493

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 @author Jeffrey Rodriguez @

  *
  */
@SuppressWarnings({"ALL"})
public class Base64 {

    // Create constants pertaining to the chunk requirement
    static final int CHUNK_SIZE = 76;
    static final byte[] CHUNK_SEPARATOR = "\n".getBytes();

    // Create numerical and byte constants
    static final int BASELENGTH = 255;
    static final int LOOKUPLENGTH = 64;
    static final int TWENTYFOURBITGROUP = 24;
    static final int EIGHTBIT = 8;
    static final int SIXTEENBIT = 16;
    static final int SIXBIT = 6;
    static final int FOURBYTE = 4;
    static final int SIGN = -128;
    static final byte PAD = (byte) '=';

    // Create arrays to hold the base64 characters and a
    // lookup for base64 chars
    private static byte[] base64Alphabet = new byte[BASELENGTH];
    private static byte[] lookUpBase64Alphabet = new byte[LOOKUPLENGTH];

    // Populating the lookup and character arrays
    static {
        for (int i = 0; i < BASELENGTH; i++) {
            base64Alphabet[i] = (byte) -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) '/';
    }

    private static boolean isBase64(byte octect) {