A class to encode Base64 streams and strings. : Base64 « Development Class « Java

1. Java
2. Development Class
3. Base64

A class to encode Base64 streams and strings.

     
/*
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;
    }
  }
}

   
    
    
    
    
  

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