Java tutorial
/* * JCommon : a free general purpose class library for the Java(tm) platform * * * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jcommon/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library 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 Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Java is a trademark or registered trademark of Sun Microsystems, Inc. * in the United States and other countries.] * * ------------------------------------- * AbstractElementDefinitionHandler.java * ------------------------------------- * (C)opyright 2003-2005, by Thomas Morgner and Contributors. * * Original Author: Kevin Kelley <kelley@ruralnet.net> - * 30718 Rd. 28, La Junta, CO, 81050 USA. * * $Id: Base64.java,v 1.4 2005/10/18 13:33:53 mungady Exp $ * * Changes * ------------------------- * 23.09.2003 : Initial version * */ import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.ByteArrayOutputStream; import java.io.CharArrayWriter; import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.FileReader; import java.io.FileWriter; import java.io.InputStream; import java.io.OutputStream; import java.io.Reader; import java.io.Writer; /** * Provides encoding of raw bytes to base64-encoded characters, and decoding of * base64 characters to raw bytes. date: 06 August 1998 modified: 14 February * 2000 modified: 22 September 2000 * * @author Kevin Kelley (kelley@ruralnet.net) * @version 1.3 */ public class Base64 { private Base64() { } /** * returns an array of base64-encoded characters to represent the passed data * array. * * @param data * the array of bytes to encode * @return base64-coded character array. */ public static char[] encode(final byte[] data) { final char[] out = new char[((data.length + 2) / 3) * 4]; // // 3 bytes encode to 4 chars. Output is always an even // multiple of 4 characters. // for (int i = 0, index = 0; i < data.length; i += 3, index += 4) { boolean quad = false; boolean trip = false; int val = (0xFF & data[i]); val <<= 8; if ((i + 1) < data.length) { val |= (0xFF & data[i + 1]); trip = true; } val <<= 8; if ((i + 2) < data.length) { val |= (0xFF & data[i + 2]); quad = true; } out[index + 3] = alphabet[(quad ? (val & 0x3F) : 64)]; val >>= 6; out[index + 2] = alphabet[(trip ? (val & 0x3F) : 64)]; val >>= 6; out[index + 1] = alphabet[val & 0x3F]; val >>= 6; out[index + 0] = alphabet[val & 0x3F]; } return out; } /** * Decodes a BASE-64 encoded stream to recover the original data. White space * before and after will be trimmed away, but no other manipulation of the * input will be performed. * * As of version 1.2 this method will properly handle input containing junk * characters (newlines and the like) rather than throwing an error. It does * this by pre-parsing the input and generating from that a count of VALID * input characters. * * @param data * the character data. * * @return The decoded data. */ public static byte[] decode(final char[] data) { // as our input could contain non-BASE64 data (newlines, // whitespace of any sort, whatever) we must first adjust // our count of USABLE data so that... // (a) we don't misallocate the output array, and // (b) think that we miscalculated our data length // just because of extraneous throw-away junk int tempLen = data.length; for (int ix = 0; ix < data.length; ix++) { if ((data[ix] > 255) || codes[data[ix]] < 0) { --tempLen; // ignore non-valid chars and padding } } // calculate required length: // -- 3 bytes for every 4 valid base64 chars // -- plus 2 bytes if there are 3 extra base64 chars, // or plus 1 byte if there are 2 extra. int len = (tempLen / 4) * 3; if ((tempLen % 4) == 3) { len += 2; } if ((tempLen % 4) == 2) { len += 1; } final byte[] out = new byte[len]; int shift = 0; // # of excess bits stored in accum int accum = 0; // excess bits int index = 0; // we now go through the entire array (NOT using the 'tempLen' value) for (int ix = 0; ix < data.length; ix++) { final int value = (data[ix] > 255) ? -1 : codes[data[ix]]; if (value >= 0) { // skip over non-code accum <<= 6; // bits shift up by 6 each time thru shift += 6; // loop, with new bits being put in accum |= value; // at the bottom. if (shift >= 8) { // whenever there are 8 or more shifted in, shift -= 8; // write them out (from the top, leaving any out[index++] = // excess at the bottom for next iteration. (byte) ((accum >> shift) & 0xff); } } // we will also have skipped processing a padding null byte ('=') here; // these are used ONLY for padding to an even length and do not legally // occur as encoded data. for this reason we can ignore the fact that // no index++ operation occurs in that special case: the out[] array is // initialized to all-zero bytes to start with and that works to our // advantage in this combination. } // if there is STILL something wrong we just have to throw up now! if (index != out.length) { throw new Error("Miscalculated data length (wrote " + index + " instead of " + out.length + ")"); } return out; } // // code characters for values 0..63 // private static char[] alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=" .toCharArray(); // // lookup table for converting base64 characters to value in range 0..63 // private static byte[] codes = new byte[256]; static { for (int i = 0; i < 256; i++) { codes[i] = -1; } for (int i = 'A'; i <= 'Z'; i++) { codes[i] = (byte) (i - 'A'); } for (int i = 'a'; i <= 'z'; i++) { codes[i] = (byte) (26 + i - 'a'); } for (int i = '0'; i <= '9'; i++) { codes[i] = (byte) (52 + i - '0'); } codes['+'] = 62; codes['/'] = 63; } // ///////////////////////////////////////////////// // remainder (main method and helper functions) is // for testing purposes only, feel free to clip it. // ///////////////////////////////////////////////// /** * Entry point. * * @param args * the command line arguments. */ public static void main(final String[] args) { boolean decode = false; if (args.length == 0) { System.out.println("usage: java Base64 [-d[ecode]] filename"); System.exit(0); } for (int i = 0; i < args.length; i++) { if ("-decode".equalsIgnoreCase(args[i])) { decode = true; } else if ("-d".equalsIgnoreCase(args[i])) { decode = true; } } final String filename = args[args.length - 1]; final File file = new File(filename); if (!file.exists()) { System.out.println("Error: file '" + filename + "' doesn't exist!"); System.exit(0); } if (decode) { final char[] encoded = readChars(file); final byte[] decoded = decode(encoded); writeBytes(file, decoded); } else { final byte[] decoded = readBytes(file); final char[] encoded = encode(decoded); writeChars(file, encoded); } } private static byte[] readBytes(final File file) { final ByteArrayOutputStream baos = new ByteArrayOutputStream(); try { final InputStream fis = new FileInputStream(file); final InputStream is = new BufferedInputStream(fis); int count; final byte[] buf = new byte[16384]; while ((count = is.read(buf)) != -1) { if (count > 0) { baos.write(buf, 0, count); } } is.close(); } catch (Exception e) { e.printStackTrace(); } return baos.toByteArray(); } private static char[] readChars(final File file) { final CharArrayWriter caw = new CharArrayWriter(); try { final Reader fr = new FileReader(file); final Reader in = new BufferedReader(fr); int count; final char[] buf = new char[16384]; while ((count = in.read(buf)) != -1) { if (count > 0) { caw.write(buf, 0, count); } } in.close(); } catch (Exception e) { e.printStackTrace(); } return caw.toCharArray(); } private static void writeBytes(final File file, final byte[] data) { try { final OutputStream fos = new FileOutputStream(file); final OutputStream os = new BufferedOutputStream(fos); os.write(data); os.close(); } catch (Exception e) { e.printStackTrace(); } } private static void writeChars(final File file, final char[] data) { try { final Writer fos = new FileWriter(file); final Writer os = new BufferedWriter(fos); os.write(data); os.close(); } catch (Exception e) { e.printStackTrace(); } } // ///////////////////////////////////////////////// // end of test code. // ///////////////////////////////////////////////// }