Base64Encoder.java Source code

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Here is the source code for Base64Encoder.java

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/*
This file is part of Socks via HTTP.
    
This package is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
    
Socks via HTTP is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.
    
You should have received a copy of the GNU General Public License
along with Socks via HTTP; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

// Title :        Base64Encoder.java
// Version :      1.2
// Copyright :    Copyright (c) 2001-2002
// Author :       Florent CUETO  & Sebastien LEBRETON <socksviahttp@cqs.dyndns.org>
// Description :  Base 64 Encoder

//package socksviahttp.core.util;

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

/**
 * A class to encode Base64 streams and strings. See RFC 1521 section 5.2 for
 * details of the Base64 algorithm.
 * <p>
 * This class can be used for encoding strings: <blockquote>
 * 
 * <pre>
 * String unencoded = &quot;webmaster:try2gueSS&quot;;
 * String encoded = Base64Encoder.encode(unencoded);
 * </pre>
 * 
 * </blockquote> or for encoding streams: <blockquote>
 * 
 * <pre>
 * OutputStream out = new Base64Encoder(System.out);
 * </pre>
 * 
 * </blockquote>
 */

public class Base64Encoder extends FilterOutputStream {

    private static final char[] chars = { '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 charCount;
    private int carryOver;

    /**
     * Constructs a new Base64 encoder that writes output to the given
     * OutputStream.
     * 
     * @param out
     *            the output stream
     */
    public Base64Encoder(OutputStream out) {
        super(out);
    }

    /**
     * Writes the given byte to the output stream in an encoded form.
     * 
     * @exception IOException
     *                if an I/O error occurs
     */
    public void write(int b) throws IOException {
        // Take 24-bits from three octets, translate into four encoded chars
        // Break lines at 76 chars
        // If necessary, pad with 0 bits on the right at the end
        // Use = signs as padding at the end to ensure encodedLength % 4 == 0

        // Remove the sign bit,
        // thanks to Christian Schweingruber <chrigu@lorraine.ch>
        if (b < 0) {
            b += 256;
        }

        // First byte use first six bits, save last two bits
        if (charCount % 3 == 0) {
            int lookup = b >> 2;
            carryOver = b & 3; // last two bits
            out.write(chars[lookup]);
        }
        // Second byte use previous two bits and first four new bits,
        // save last four bits
        else if (charCount % 3 == 1) {
            int lookup = ((carryOver << 4) + (b >> 4)) & 63;
            carryOver = b & 15; // last four bits
            out.write(chars[lookup]);
        }
        // Third byte use previous four bits and first two new bits,
        // then use last six new bits
        else if (charCount % 3 == 2) {
            int lookup = ((carryOver << 2) + (b >> 6)) & 63;
            out.write(chars[lookup]);
            lookup = b & 63; // last six bits
            out.write(chars[lookup]);
            carryOver = 0;
        }
        charCount++;

        // Add newline every 76 output chars (that's 57 input chars)
        if (charCount % 57 == 0) {
            out.write('\n');
        }
    }

    /**
     * Writes the given byte array to the output stream in an encoded form.
     * 
     * @param b
     *            the data to be written
     * @param off
     *            the start offset of the data
     * @param len
     *            the length of the data
     * @exception IOException
     *                if an I/O error occurs
     */
    public void write(byte[] b, int off, int len) throws IOException {
        // This could of course be optimized
        for (int i = 0; i < len; i++) {
            write(b[off + i]);
        }
    }

    /**
     * Closes the stream, this MUST be called to ensure proper padding is
     * written to the end of the output stream.
     * 
     * @exception IOException
     *                if an I/O error occurs
     */
    public void close() throws IOException {
        // Handle leftover bytes
        if (charCount % 3 == 1) { // one leftover
            int lookup = (carryOver << 4) & 63;
            out.write(chars[lookup]);
            out.write('=');
            out.write('=');
        } else if (charCount % 3 == 2) { // two leftovers
            int lookup = (carryOver << 2) & 63;
            out.write(chars[lookup]);
            out.write('=');
        }
        super.close();
    }

    /**
     * Returns the encoded form of the given unencoded string.
     * 
     * @param unencoded
     *            the string to encode
     * @return the encoded form of the unencoded string
     */
    public static String encode(String unencoded) {
        ByteArrayOutputStream out = new ByteArrayOutputStream((int) (unencoded.length() * 1.37));
        Base64Encoder encodedOut = new Base64Encoder(out);

        byte[] bytes = null;
        try {
            bytes = unencoded.getBytes("8859_1");
        } catch (UnsupportedEncodingException ignored) {
        }

        try {
            encodedOut.write(bytes);
            encodedOut.close();

            return out.toString("8859_1");
        } catch (IOException ignored) {
            return null;
        }
    }
}