gistfile1.java

package uk.org.netvu.util;

import org.apache.log4j.Level;
import org.apache.log4j.Logger;

import java.io.ByteArrayOutputStream;
import java.io.FilterOutputStream;
import java.io.IOException;

public class Base64Encoder {
    private static final Logger log = Logger.getLogger(Base64Encoder.class);

    public static String encode(String s) {
        final ByteArrayOutputStream bOut = new ByteArrayOutputStream();
        final Base64OutputStream out = new Base64OutputStream(bOut);
        try {
            out.write(s.getBytes());
            out.flush();
        }
        catch (IOException ex) {
            if (log.isEnabledFor(Level.DEBUG)) {
                log.debug(ex.getMessage());
            }
        }
        return bOut.toString();
    }
}

class Base64OutputStream extends FilterOutputStream {
    Base64OutputStream(ByteArrayOutputStream os) {
        super(os);
    }

    @Override
    public void write(byte[] data) throws IOException {
        for (byte aData : data) {
            write(aData);
        }
    }

    public void write(byte b) throws IOException {
        inbuf[i] = b;
        i++;
        if (i == 3) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[((inbuf[0] & 0x03) << 4) |
                    ((inbuf[1] & 0xF0) >> 4)]);
            super.write(toBase64[((inbuf[1] & 0x0F) << 2) |
                    ((inbuf[2] & 0xC0) >> 6)]);
            super.write(toBase64[inbuf[2] & 0x3F]);
            col += 4;
            i = 0;
            if (col >= 76) {
                super.write('\n');
                col = 0;
            }
        }
    }

    @Override
    public void flush() throws IOException {
        if (i == 1) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[(inbuf[0] & 0x03) << 4]);
            super.write('=');
            super.write('=');
        } else if (i == 2) {
            super.write(toBase64[(inbuf[0] & 0xFC) >> 2]);
            super.write(toBase64[((inbuf[0] & 0x03) << 4) |
                    ((inbuf[1] & 0xF0) >> 4)]);
            super.write(toBase64[(inbuf[1] & 0x0F) << 2]);
            super.write('=');
        }
    }

    private static final char[] toBase64 =
            {
                    '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', '+', '/'
            };

    private int col = 0;
    private int i = 0;
    private final byte[] inbuf = new byte[3];

}