Mega Code Archive
Provides encoding of raw bytes to base64-encoded characters, and decoding of base64 characters to raw bytes
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/*
* 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.
// /////////////////////////////////////////////////
}
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