ASCIIHexOutputStream.java

// Copyright 2001, FreeHEP.
package org.xmind.org.freehep.util.io;

import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
 * The ASCIIHexOutputStream encodes binary data as ASCII Hexadecimal. The exact
 * definition of ASCII Hex encoding can be found in the PostScript Language
 * Reference (3rd ed.) chapter 3.13.3.
 *
 * @author Mark Donszelmann
 * @author Jason Wong
 */
public class ASCIIHexOutputStream extends FilterOutputStream implements
        FinishableOutputStream {

    private final static int MAX_CHARS_PER_LINE = 80;

    private int characters;

    private boolean end;

    private String newline = "\n"; //$NON-NLS-1$

    /**
     * Create an ASCIIHex Output Stream for given stream.
     *
     * @param out
     *            output stream to use
     */
    public ASCIIHexOutputStream(OutputStream out) {
        super(out);
        characters = MAX_CHARS_PER_LINE;
        end = false;
        try {
            newline = System.getProperty("line.separator"); //$NON-NLS-1$
        } catch (SecurityException e) {
            // ignored;
        }
    }

    @Override
    public void write(int b) throws IOException {
        String s = Integer.toHexString(b & 0x00FF);
        switch (s.length()) {
        case 1:
            writeChar('0');
            writeChar(s.charAt(0));
            break;
        case 2:
            writeChar(s.charAt(0));
            writeChar(s.charAt(1));
            break;
        default:
            throw new IOException("ASCIIHexOutputStream: byte '" + b //$NON-NLS-1$
                    + "' was encoded in less than 1 or more than 2 chars"); //$NON-NLS-1$
        }
    }

    public void finish() throws IOException {
        if (!end) {
            end = true;
            writeChar('>');
            writeNewLine();
            flush();
            if (out instanceof FinishableOutputStream) {
                ((FinishableOutputStream) out).finish();
            }
        }
    }

    @Override
    public void close() throws IOException {
        finish();
        super.close();
    }

    private void writeChar(int b) throws IOException {
        if (characters == 0) {
            characters = MAX_CHARS_PER_LINE;
            writeNewLine();
        }
        characters--;
        super.write(b);
    }

    private void writeNewLine() throws IOException {
        // write a newline
        for (int i = 0; i < newline.length(); i++) {
            super.write(newline.charAt(i));
        }
    }
}