public class Base64Encoder {  
    private static final char last2byte = (char) Integer  
            .parseInt("00000011", 2);  
    private static final char last4byte = (char) Integer  
            .parseInt("00001111", 2);  
    private static final char last6byte = (char) Integer  
            .parseInt("00111111", 2);  
    private static final char lead6byte = (char) Integer  
            .parseInt("11111100", 2);  
    private static final char lead4byte = (char) Integer  
            .parseInt("11110000", 2);  
    private static final char lead2byte = (char) Integer  
            .parseInt("11000000", 2);  
    private static final char[] encodeTable = 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', '+', '/' };  
  
    /** 
     * Base64 encoding. 
     *  
     * @param from 
     *            The src data. 
     * @return 
     */  
    public static String encode(byte[] from) {  
        StringBuffer to = new StringBuffer((int) (from.length * 1.34) + 3);  
        int num = 0;  
        char currentByte = 0;  
        for (int i = 0; i < from.length; i++) {  
            num = num % 8;  
            while (num < 8) {  
                switch (num) {  
                case 0:  
                    currentByte = (char) (from[i] & lead6byte);  
                    currentByte = (char) (currentByte >>> 2);  
                    break;  
                case 2:  
                    currentByte = (char) (from[i] & last6byte);  
                    break;  
                case 4:  
                    currentByte = (char) (from[i] & last4byte);  
                    currentByte = (char) (currentByte << 2);  
                    if ((i + 1) < from.length) {  
                        currentByte |= (from[i + 1] & lead2byte) >>> 6;  
                    }  
                    break;  
                case 6:  
                    currentByte = (char) (from[i] & last2byte);  
                    currentByte = (char) (currentByte << 4);  
                    if ((i + 1) < from.length) {  
                        currentByte |= (from[i + 1] & lead4byte) >>> 4;  
                    }  
                    break;  
                }  
                to.append(encodeTable[currentByte]);  
                num += 6;  
            }  
        }  
        if (to.length() % 4 != 0) {  
            for (int i = 4 - to.length() % 4; i > 0; i--) {  
                to.append("=");  
            }  
        }  
        return to.toString();  
    }  
}