fr.opensagres.xdocreport.core.utils.Base64Utility Maven / Gradle / Ivy
/**
* Copyright (C) 2011-2012 The XDocReport Team
*
* All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
package fr.opensagres.xdocreport.core.utils;
/**
* Base64Utility - this static class provides useful base64
* encoding utilities.
*
* @author Darach Ennis
* @author Craig Ryan
*/
// Java imports
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Writer;
import java.util.logging.Logger;
import fr.opensagres.xdocreport.core.io.IOUtils;
import fr.opensagres.xdocreport.core.logging.LogUtils;
/**
* This class converts to/from base64. The alternative conversions include: encode: byte[] into String byte[] into
* char[] byte[] into OutStream byte[] into Writer decode: char[] into byte[] String into byte[] char[] into OutStream
* String into OutStream
*/
public final class Base64Utility
{
private static final Logger LOG = LogUtils.getLogger( Base64Utility.class );
// base 64 character set
//
private static final char[] BCS = { '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', '+', '/' };
// base 64 wadding
private static final char PAD = '=';
// size of base 64 decode table
private static final int BDTSIZE = 128;
// base 64 decode table
private static final byte[] BDT = new byte[128];
private static final int PAD_SIZE0 = 1;
private static final int PAD_SIZE4 = 2;
private static final int PAD_SIZE8 = 3;
// class static intializer for building decode table
static
{
for ( int i = 0; i < BDTSIZE; i++ )
{
BDT[i] = Byte.MAX_VALUE;
}
for ( int i = 0; i < BCS.length; i++ )
{
BDT[BCS[i]] = (byte) i;
}
}
private Base64Utility()
{
// utility class, never constructed
}
/**
* The decode_chunk routine decodes a chunk of data into its native encoding. base64 encodes each 3
* octets of data into 4 characters from a limited 64 character set. The 3 octets are joined to form 24 bits which
* are then split into 4 x 6bit values. Each 6 bit value is then used as an index into the 64 character table of
* base64 chars. If the total data length is not a 3 octet multiple the '=' char is used as padding for the final 4
* char group, either 1 octet + '==' or 2 octets + '='.
*
* @param id The input data to be processed
* @param o The offset from which to begin processing
* @param l The length (bound) at which processing is to end
* @return The decoded data
* @exception Base64Exception Thrown is processing fails due to formatting exceptions in the encoded data
*/
public static byte[] decodeChunk( char[] id, int o, int l )
throws Base64Exception
{
// Keep it simple - must be >= 4. Unpadded
// base64 data contain < 3 octets is invalid.
//
if ( ( l - o ) < 4 )
{
return null;
}
char[] ib = new char[4];
int ibcount = 0;
// cryan. Calc the num of octets. Each 4 chars of base64 chars
// (representing 24 bits) encodes 3 octets.
//
int octetCount = 3 * ( l / 4 );
// Final 4 chars may contain 3 octets or padded to contain
// 1 or 2 octets.
//
if ( id[l - 1] == PAD )
{
// TT== means last 4 chars encode 8 bits (ie subtract 2)
// TTT= means last 4 chars encode 16 bits (ie subtract 1)
octetCount -= ( id[l - 2] == PAD ) ? 2 : 1;
}
byte[] ob = new byte[octetCount];
int obcount = 0;
for ( int i = o; i < o + l && i < id.length; i++ )
{
if ( id[i] == PAD || id[i] < BDT.length && BDT[id[i]] != Byte.MAX_VALUE )
{
ib[ibcount++] = id[i];
// Decode each 4 char sequence.
//
if ( ibcount == ib.length )
{
ibcount = 0;
obcount += processEncodeme( ib, ob, obcount );
}
}
}
if ( obcount != ob.length )
{
byte[] tmp = new byte[obcount];
System.arraycopy( ob, 0, tmp, 0, obcount );
ob = tmp;
}
return ob;
}
public static byte[] decode( String id )
throws Base64Exception
{
try
{
char[] cd = id.toCharArray();
return decodeChunk( cd, 0, cd.length );
}
catch ( Exception e )
{
LOG.warning( "Invalid base64 encoded string : " + id );
throw new Base64Exception( "Runtime exception in Base64Utility.decode() during output", e );
}
}
public static void decode( char[] id, int o, int l, OutputStream ostream )
throws Base64Exception
{
try
{
ostream.write( decodeChunk( id, o, l ) );
}
catch ( Exception e )
{
LOG.warning( "Invalid base64 encoded string : " + new String( id ) );
throw new Base64Exception( "Runtime exception in Base64Utility.decode() during output", e );
}
}
public static void decode( String id, OutputStream ostream )
throws Base64Exception
{
try
{
char[] cd = id.toCharArray();
ostream.write( decodeChunk( cd, 0, cd.length ) );
}
catch ( IOException ioe )
{
throw new Base64Exception( "decode() to outstream raised IOException", ioe );
}
catch ( Exception e )
{
LOG.warning( "Invalid base64 encoded string : " + id );
throw new Base64Exception( "Runtime exception in Base64Utility.decode() during output", e );
}
}
public static String encode( InputStream in )
throws IOException
{
byte[] bytes = IOUtils.toByteArray( in );
String encoded = Base64Utility.encode( bytes );
return encoded;
}
// Returns base64 representation of specified byte array.
//
public static String encode( byte[] id )
{
char[] cd = encodeChunk( id, 0, id.length );
return new String( cd, 0, cd.length );
}
// Returns base64 representation of specified byte array.
//
public static char[] encodeChunk( byte[] id, int o, int l )
{
if ( l <= 0 )
{
return null;
}
char[] out;
// If not a multiple of 3 octets then a final padded 4 char
// slot is needed.
//
if ( ( l - o ) % 3 == 0 )
{
out = new char[l / 3 * 4];
}
else
{
out = new char[l / 3 * 4 + 4];
}
int rindex = o;
int windex = 0;
int rest = l - o;
while ( rest >= 3 )
{
int i = ( ( id[rindex] & 0xff ) << 16 ) + ( ( id[rindex + 1] & 0xff ) << 8 ) + ( id[rindex + 2] & 0xff );
out[windex++] = BCS[i >> 18];
out[windex++] = BCS[( i >> 12 ) & 0x3f];
out[windex++] = BCS[( i >> 6 ) & 0x3f];
out[windex++] = BCS[i & 0x3f];
rindex += 3;
rest -= 3;
}
if ( rest == 1 )
{
int i = id[rindex] & 0xff;
out[windex++] = BCS[i >> 2];
out[windex++] = BCS[( i << 4 ) & 0x3f];
out[windex++] = PAD;
out[windex++] = PAD;
}
else if ( rest == 2 )
{
int i = ( ( id[rindex] & 0xff ) << 8 ) + ( id[rindex + 1] & 0xff );
out[windex++] = BCS[i >> 10];
out[windex++] = BCS[( i >> 4 ) & 0x3f];
out[windex++] = BCS[( i << 2 ) & 0x3f];
out[windex++] = PAD;
}
return out;
}
//
// Outputs base64 representation of the specified byte array
// to a byte stream.
//
public static void encodeChunk( byte[] id, int o, int l, OutputStream ostream )
throws Base64Exception
{
try
{
ostream.write( new String( encodeChunk( id, o, l ) ).getBytes() );
}
catch ( IOException e )
{
throw new Base64Exception( "encode() to outstream raised IOException", e );
}
}
// Outputs base64 representation of the specified byte
// array to a character stream.
//
public static void encode( byte[] id, int o, int l, Writer writer )
throws Base64Exception
{
try
{
writer.write( encodeChunk( id, o, l ) );
}
catch ( IOException e )
{
throw new Base64Exception( "encode() to Writer raised exception", e );
}
}
// ---- Private static methods --------------------------------------
/**
* The process routine processes an atomic base64 unit of encoding (encodeme) into its native encoding.
* This class is used by decode routines to do the grunt work of decoding base64 encoded information
*
* @param ib Input character buffer of encoded bytes
* @param ob Output byte buffer of decoded bytes
* @param p Pointer to the encodeme of interest
* @return The decoded encodeme
* @exception Base64Exception Thrown is processing fails due to formatting exceptions in the encoded data
*/
private static int processEncodeme( char[] ib, byte[] ob, int p )
throws Base64Exception
{
int spad = PAD_SIZE8;
if ( ib[3] == PAD )
{
spad = PAD_SIZE4;
}
if ( ib[2] == PAD )
{
spad = PAD_SIZE0;
}
int b0 = BDT[ib[0]];
int b1 = BDT[ib[1]];
int b2 = BDT[ib[2]];
int b3 = BDT[ib[3]];
switch ( spad )
{
case PAD_SIZE0:
ob[p] = (byte) ( b0 << 2 & 0xfc | b1 >> 4 & 0x3 );
return PAD_SIZE0;
case PAD_SIZE4:
ob[p++] = (byte) ( b0 << 2 & 0xfc | b1 >> 4 & 0x3 );
ob[p] = (byte) ( b1 << 4 & 0xf0 | b2 >> 2 & 0xf );
return PAD_SIZE4;
case PAD_SIZE8:
ob[p++] = (byte) ( b0 << 2 & 0xfc | b1 >> 4 & 0x3 );
ob[p++] = (byte) ( b1 << 4 & 0xf0 | b2 >> 2 & 0xf );
ob[p] = (byte) ( b2 << 6 & 0xc0 | b3 & 0x3f );
return PAD_SIZE8;
default:
// We should never get here
throw new IllegalStateException();
}
}
}