Question

Based on my original question about RSA and Base64 encoding and the comments there I am wondering what is the best approach to write a Base64OutputStream (or Input Stream). I originally had called it Base64PrintWriter and extended it from PrintWriter passing a PrintWriter to the Constructor.

import org.bouncycastle.util.encoders.Base64;

public class Base64OutputStream extends FilterOutputStream {

    public Base64OutputStream(OutputStream out) {
        super(out);
    }

    public void write(byte[] decodedBytes) throws IOException {
        byte[] base64Message = Base64.encode(decodedBytes);
        super.write(base64Message);
    }

    public void writeln(byte[] decodedBytes) throws IOException {
        write(decodedBytes);
        super.write("\n".getBytes());
        super.flush();
    }
}

I changed my original implementation to the one above and I initialize it with:

Base64OutputStream base64encoder = new Base64OutputStream(socket.getOutputStream());

My questions are:

1. Is this a good design?
2. Can it be done better?
3. Have I applied the decorator pattern correctly.
4. Is it good to extend FilteredOutputStream instead of OutputStream? Oracle indicates it is good but are there any disadvantages or reasons to still extend from OutputStream?
5. And should I additionally decorate it with BufferedOutputStream when I call the constructor?

Answer 1

If you are amenable to using open source, you can look at Apache Commons Codec. It contains a Base64OutputStream that should meet you needs.