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Google API Client Library for Java. Supports Java 5 (or higher) desktop (SE)
and web (EE), Android, and Google App Engine.
/*
* Copyright (c) 2010 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.google.api.client.util;
// This code was copied from code at http://iharder.sourceforge.net/base64/
// Lots of extraneous features were removed: encodeObject, decodeToObject,
// encodeFromFile, encodeFileToFile, encodeToFile, InputStream, OutputStream,
// decode(String, ...), encode(ByteBuffer,...), encode3to4 not used, URL_SAFE
// and ORDERED *bets, options
// original class JavaDoc:
/*
* Encodes and decodes to and from Base64 notation.
* Homepage: http://iharder.net/base64.
*
* Example:
*
* String encoded = Base64.encode( myByteArray );
*
* byte[] myByteArray = Base64.decode( encoded );
*
* The options parameter, which appears in a few places, is used to pass
* several pieces of information to the encoder. In the "higher level" methods such as
* encodeBytes( bytes, options ) the options parameter can be used to indicate such
* things as first gzipping the bytes before encoding them, not inserting linefeeds,
* and encoding using the URL-safe and Ordered dialects.
*
* Note, according to RFC3548,
* Section 2.1, implementations should not add line feeds unless explicitly told
* to do so. I've got Base64 set to this behavior now, although earlier versions
* broke lines by default.
*
* The constants defined in Base64 can be OR-ed together to combine options, so you
* might make a call like this:
*
* String encoded = Base64.encodeBytes( mybytes, Base64.GZIP | Base64.DO_BREAK_LINES );
* to compress the data before encoding it and then making the output have newline characters.
* Also...
* String encoded = Base64.encodeBytes( crazyString.getBytes() );
*
*
*
*
* Change Log:
*
*
* - v2.3.7 - Fixed subtle bug when base 64 input stream contained the
* value 01111111, which is an invalid base 64 character but should not
* throw an ArrayIndexOutOfBoundsException either. Led to discovery of
* mishandling (or potential for better handling) of other bad input
* characters. You should now get an IOException if you try decoding
* something that has bad characters in it.
* - v2.3.6 - Fixed bug when breaking lines and the final byte of the encoded
* string ended in the last column; the buffer was not properly shrunk and
* contained an extra (null) byte that made it into the string.
* - v2.3.5 - Fixed bug in {@code encodeFromFile} where estimated buffer size
* was wrong for files of size 31, 34, and 37 bytes.
* - v2.3.4 - Fixed bug when working with gzipped streams whereby flushing
* the Base64.OutputStream closed the Base64 encoding (by padding with equals
* signs) too soon. Also added an option to suppress the automatic decoding
* of gzipped streams. Also added experimental support for specifying a
* class loader when using the
* {@code decodeToObject(java.lang.String, int, java.lang.ClassLoader)}
* method.
* - v2.3.3 - Changed default char encoding to US-ASCII which reduces the internal Java
* footprint with its CharEncoders and so forth. Fixed some javadocs that were
* inconsistent. Removed imports and specified things like java.io.IOException
* explicitly inline.
* - v2.3.2 - Reduced memory footprint! Finally refined the "guessing" of how big the
* final encoded data will be so that the code doesn't have to create two output
* arrays: an oversized initial one and then a final, exact-sized one. Big win
* when using the {@code encodeBytesToBytes(byte[])} family of methods (and not
* using the gzip options which uses a different mechanism with streams and stuff).
* - v2.3.1 - Added {@code encodeBytesToBytes(byte[], int, int, int)} and some
* similar helper methods to be more efficient with memory by not returning a
* String but just a byte array.
* - v2.3 - This is not a drop-in replacement! This is two years of comments
* and bug fixes queued up and finally executed. Thanks to everyone who sent
* me stuff, and I'm sorry I wasn't able to distribute your fixes to everyone else.
* Much bad coding was cleaned up including throwing exceptions where necessary
* instead of returning null values or something similar. Here are some changes
* that may affect you:
*
* - Does not break lines, by default. This is to keep in compliance with
* RFC3548.
* - Throws exceptions instead of returning null values. Because some operations
* (especially those that may permit the GZIP option) use IO streams, there
* is a possiblity of an java.io.IOException being thrown. After some discussion and
* thought, I've changed the behavior of the methods to throw java.io.IOExceptions
* rather than return null if ever there's an error. I think this is more
* appropriate, though it will require some changes to your code. Sorry,
* it should have been done this way to begin with.
* - Removed all references to System.out, System.err, and the like.
* Shame on me. All I can say is sorry they were ever there.
* - Throws NullPointerExceptions and IllegalArgumentExceptions as needed
* such as when passed arrays are null or offsets are invalid.
* - Cleaned up as much javadoc as I could to avoid any javadoc warnings.
* This was especially annoying before for people who were thorough in their
* own projects and then had gobs of javadoc warnings on this file.
*
* - v2.2.1 - Fixed bug using URL_SAFE and ORDERED encodings. Fixed bug
* when using very small files (~< 40 bytes).
* - v2.2 - Added some helper methods for encoding/decoding directly from
* one file to the next. Also added a main() method to support command line
* encoding/decoding from one file to the next. Also added these Base64 dialects:
*
* - The default is RFC3548 format.
* - Calling Base64.setFormat(Base64.BASE64_FORMAT.URLSAFE_FORMAT) generates
* URL and file name friendly format as described in Section 4 of RFC3548.
* http://www.faqs.org/rfcs/rfc3548.html
* - Calling Base64.setFormat(Base64.BASE64_FORMAT.ORDERED_FORMAT) generates
* URL and file name friendly format that preserves lexical ordering as described
* in http://www.faqs.org/qa/rfcc-1940.html
*
* Special thanks to Jim Kellerman at http://www.powerset.com/
* for contributing the new Base64 dialects.
*
*
* - v2.1 - Cleaned up javadoc comments and unused variables and methods. Added
* some convenience methods for reading and writing to and from files.
* - v2.0.2 - Now specifies UTF-8 encoding in places where the code fails on systems
* with other encodings (like EBCDIC).
* - v2.0.1 - Fixed an error when decoding a single byte, that is, when the
* encoded data was a single byte.
* - v2.0 - I got rid of methods that used booleans to set options.
* Now everything is more consolidated and cleaner. The code now detects
* when data that's being decoded is gzip-compressed and will decompress it
* automatically. Generally things are cleaner. You'll probably have to
* change some method calls that you were making to support the new
* options format (ints that you "OR" together).
* - v1.5.1 - Fixed bug when decompressing and decoding to a
* byte[] using decode( String s, boolean gzipCompressed ).
* Added the ability to "suspend" encoding in the Output Stream so
* you can turn on and off the encoding if you need to embed base64
* data in an otherwise "normal" stream (like an XML file).
* - v1.5 - Output stream pases on flush() command but doesn't do anything itself.
* This helps when using GZIP streams.
* Added the ability to GZip-compress objects before encoding them.
* - v1.4 - Added helper methods to read/write files.
* - v1.3.6 - Fixed OutputStream.flush() so that 'position' is reset.
* - v1.3.5 - Added flag to turn on and off line breaks. Fixed bug in input stream
* where last buffer being read, if not completely full, was not returned.
* - v1.3.4 - Fixed when "improperly padded stream" error was thrown at the wrong time.
* - v1.3.3 - Fixed I/O streams which were totally messed up.
*
*
*
* I am placing this code in the Public Domain. Do with it as you will.
* This software comes with no guarantees or warranties but with
* plenty of well-wishing instead!
* Please visit http://iharder.net/base64
* periodically to check for updates or to contribute improvements.
*
*
* @author Robert Harder
* @author [email protected]
* @version 2.3.7
*/
/**
* Encodes and decodes to and from Base64 notation.
*
* Homepage: http://iharder.net/base64.
*
*
* @author Robert Harder ([email protected])
* @since 1.0
*/
public class Base64 {
/* ******** P R I V A T E F I E L D S ******** */
/** The equals sign (=) as a byte. */
private final static byte EQUALS_SIGN = (byte)'=';
private final static byte WHITE_SPACE_ENC = -5; // Indicates white space in encoding
private final static byte EQUALS_SIGN_ENC = -1; // Indicates equals sign in encoding
/* ******** S T A N D A R D B A S E 6 4 A L P H A B E T ******** */
/** The 64 valid Base64 values. */
/* Host platform me be something funny like EBCDIC, so we hardcode these values. */
private final static byte[] ALPHABET = {
(byte)'A', (byte)'B', (byte)'C', (byte)'D', (byte)'E', (byte)'F', (byte)'G',
(byte)'H', (byte)'I', (byte)'J', (byte)'K', (byte)'L', (byte)'M', (byte)'N',
(byte)'O', (byte)'P', (byte)'Q', (byte)'R', (byte)'S', (byte)'T', (byte)'U',
(byte)'V', (byte)'W', (byte)'X', (byte)'Y', (byte)'Z',
(byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f', (byte)'g',
(byte)'h', (byte)'i', (byte)'j', (byte)'k', (byte)'l', (byte)'m', (byte)'n',
(byte)'o', (byte)'p', (byte)'q', (byte)'r', (byte)'s', (byte)'t', (byte)'u',
(byte)'v', (byte)'w', (byte)'x', (byte)'y', (byte)'z',
(byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5',
(byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'+', (byte)'/'
};
/**
* Translates a Base64 value to either its 6-bit reconstruction value
* or a negative number indicating some other meaning.
**/
private final static byte[] DECODABET = {
-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 0 - 8
-5,-5, // Whitespace: Tab and Linefeed
-9,-9, // Decimal 11 - 12
-5, // Whitespace: Carriage Return
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 14 - 26
-9,-9,-9,-9,-9, // Decimal 27 - 31
-5, // Whitespace: Space
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 33 - 42
62, // Plus sign at decimal 43
-9,-9,-9, // Decimal 44 - 46
63, // Slash at decimal 47
52,53,54,55,56,57,58,59,60,61, // Numbers zero through nine
-9,-9,-9, // Decimal 58 - 60
-1, // Equals sign at decimal 61
-9,-9,-9, // Decimal 62 - 64
0,1,2,3,4,5,6,7,8,9,10,11,12,13, // Letters 'A' through 'N'
14,15,16,17,18,19,20,21,22,23,24,25, // Letters 'O' through 'Z'
-9,-9,-9,-9,-9,-9, // Decimal 91 - 96
26,27,28,29,30,31,32,33,34,35,36,37,38, // Letters 'a' through 'm'
39,40,41,42,43,44,45,46,47,48,49,50,51, // Letters 'n' through 'z'
-9,-9,-9,-9,-9 // Decimal 123 - 127
,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 128 - 139
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 140 - 152
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 153 - 165
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 166 - 178
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 179 - 191
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 192 - 204
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 205 - 217
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 218 - 230
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9, // Decimal 231 - 243
-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9,-9 // Decimal 244 - 255
};
/** Defeats instantiation. */
private Base64(){}
/* ******** E N C O D I N G M E T H O D S ******** */
/**
* Encodes up to three bytes of the array source
* and writes the resulting four Base64 bytes to destination.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* srcOffset and destOffset.
* This method does not check to make sure your arrays
* are large enough to accomodate srcOffset + 3 for
* the source array or destOffset + 4 for
* the destination array.
* The actual number of significant bytes in your array is
* given by numSigBytes.
* This is the lowest level of the encoding methods with
* all possible parameters.
*
* @param source the array to convert
* @param srcOffset the index where conversion begins
* @param numSigBytes the number of significant bytes in your array
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @return the destination array
* @since 1.3
*/
private static byte[] encode3to4(
byte[] source, int srcOffset, int numSigBytes,
byte[] destination, int destOffset ) {
// 1 2 3
// 01234567890123456789012345678901 Bit position
// --------000000001111111122222222 Array position from threeBytes
// --------| || || || | Six bit groups to index ALPHABET
// >>18 >>12 >> 6 >> 0 Right shift necessary
// 0x3f 0x3f 0x3f Additional AND
// Create buffer with zero-padding if there are only one or two
// significant bytes passed in the array.
// We have to shift left 24 in order to flush out the 1's that appear
// when Java treats a value as negative that is cast from a byte to an int.
int inBuff = ( numSigBytes > 0 ? ((source[ srcOffset ] << 24) >>> 8) : 0 )
| ( numSigBytes > 1 ? ((source[ srcOffset + 1 ] << 24) >>> 16) : 0 )
| ( numSigBytes > 2 ? ((source[ srcOffset + 2 ] << 24) >>> 24) : 0 );
switch( numSigBytes )
{
case 3:
destination[ destOffset ] = ALPHABET[ (inBuff >>> 18) ];
destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
destination[ destOffset + 2 ] = ALPHABET[ (inBuff >>> 6) & 0x3f ];
destination[ destOffset + 3 ] = ALPHABET[ (inBuff ) & 0x3f ];
return destination;
case 2:
destination[ destOffset ] = ALPHABET[ (inBuff >>> 18) ];
destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
destination[ destOffset + 2 ] = ALPHABET[ (inBuff >>> 6) & 0x3f ];
destination[ destOffset + 3 ] = EQUALS_SIGN;
return destination;
case 1:
destination[ destOffset ] = ALPHABET[ (inBuff >>> 18) ];
destination[ destOffset + 1 ] = ALPHABET[ (inBuff >>> 12) & 0x3f ];
destination[ destOffset + 2 ] = EQUALS_SIGN;
destination[ destOffset + 3 ] = EQUALS_SIGN;
return destination;
default:
return destination;
} // end switch
} // end encode3to4
/**
* Similar to {@link #encode(byte[])} but returns
* a byte array instead of instantiating a String. This is more efficient
* if you're working with I/O streams and have large data sets to encode.
*
*
* @param source The data to convert
* @return The Base64-encoded data as a byte[] (of ASCII characters)
* @throws NullPointerException if source array is null
* @since 2.3.1
*/
public static byte[] encode( byte[] source ) {
return encode( source, 0, source.length);
}
/**
* Similar to {@link #encode(byte[], int, int)} but returns
* a byte array instead of instantiating a String. This is more efficient
* if you're working with I/O streams and have large data sets to encode.
*
*
* @param source The data to convert
* @param off Offset in array where conversion should begin
* @param len Length of data to convert
* @return The Base64-encoded data as a String
* @throws NullPointerException if source array is null
* @throws IllegalArgumentException if source array, offset, or length are invalid
* @since 2.3.1
*/
public static byte[] encode( byte[] source, int off, int len ) {
if( source == null ){
throw new NullPointerException( "Cannot serialize a null array." );
} // end if: null
if( off < 0 ){
throw new IllegalArgumentException( "Cannot have negative offset: " + off );
} // end if: off < 0
if( len < 0 ){
throw new IllegalArgumentException( "Cannot have length offset: " + len );
} // end if: len < 0
if( off + len > source.length ){
throw new IllegalArgumentException(
String.format( "Cannot have offset of %d and length of %d with array of length %d", off,len,source.length));
} // end if: off < 0
// Else, don't compress. Better not to use streams at all then.
else {
//int len43 = len * 4 / 3;
//byte[] outBuff = new byte[ ( len43 ) // Main 4:3
// + ( (len % 3) > 0 ? 4 : 0 ) // Account for padding
// + (breakLines ? ( len43 / MAX_LINE_LENGTH ) : 0) ]; // New lines
// Try to determine more precisely how big the array needs to be.
// If we get it right, we don't have to do an array copy, and
// we save a bunch of memory.
int encLen = ( len / 3 ) * 4 + ( len % 3 > 0 ? 4 : 0 ); // Bytes needed for actual encoding
byte[] outBuff = new byte[ encLen ];
int d = 0;
int e = 0;
int len2 = len - 2;
int lineLength = 0;
for( ; d < len2; d+=3, e+=4 ) {
encode3to4( source, d+off, 3, outBuff, e );
lineLength += 4;
} // end for: each piece of array
if( d < len ) {
encode3to4( source, d+off, len - d, outBuff, e );
e += 4;
} // end if: some padding needed
// Only resize array if we didn't guess it right.
if( e <= outBuff.length - 1 ){
// If breaking lines and the last byte falls right at
// the line length (76 bytes per line), there will be
// one extra byte, and the array will need to be resized.
// Not too bad of an estimate on array size, I'd say.
byte[] finalOut = new byte[e];
System.arraycopy(outBuff,0, finalOut,0,e);
//System.err.println("Having to resize array from " + outBuff.length + " to " + e );
return finalOut;
} else {
//System.err.println("No need to resize array.");
return outBuff;
}
} // end else: don't compress
} // end encodeBytesToBytes
/* ******** D E C O D I N G M E T H O D S ******** */
/**
* Decodes four bytes from array source
* and writes the resulting bytes (up to three of them)
* to destination.
* The source and destination arrays can be manipulated
* anywhere along their length by specifying
* srcOffset and destOffset.
* This method does not check to make sure your arrays
* are large enough to accomodate srcOffset + 4 for
* the source array or destOffset + 3 for
* the destination array.
* This method returns the actual number of bytes that
* were converted from the Base64 encoding.
* This is the lowest level of the decoding methods with
* all possible parameters.
*
*
* @param source the array to convert
* @param srcOffset the index where conversion begins
* @param destination the array to hold the conversion
* @param destOffset the index where output will be put
* @return the number of decoded bytes converted
* @throws NullPointerException if source or destination arrays are null
* @throws IllegalArgumentException if srcOffset or destOffset are invalid
* or there is not enough room in the array.
* @since 1.3
*/
private static int decode4to3(
byte[] source, int srcOffset,
byte[] destination, int destOffset) {
// Lots of error checking and exception throwing
if( source == null ){
throw new NullPointerException( "Source array was null." );
} // end if
if( destination == null ){
throw new NullPointerException( "Destination array was null." );
} // end if
if( srcOffset < 0 || srcOffset + 3 >= source.length ){
throw new IllegalArgumentException( String.format(
"Source array with length %d cannot have offset of %d and still process four bytes.", source.length, srcOffset ) );
} // end if
if( destOffset < 0 || destOffset +2 >= destination.length ){
throw new IllegalArgumentException( String.format(
"Destination array with length %d cannot have offset of %d and still store three bytes.", destination.length, destOffset ) );
} // end if
// Example: Dk==
if( source[ srcOffset + 2] == EQUALS_SIGN ) {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1] ] << 24 ) >>> 12 );
int outBuff = ( ( DECODABET[ source[ srcOffset ] ] & 0xFF ) << 18 )
| ( ( DECODABET[ source[ srcOffset + 1] ] & 0xFF ) << 12 );
destination[ destOffset ] = (byte)( outBuff >>> 16 );
return 1;
}
// Example: DkL=
else if( source[ srcOffset + 3 ] == EQUALS_SIGN ) {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
// | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 );
int outBuff = ( ( DECODABET[ source[ srcOffset ] ] & 0xFF ) << 18 )
| ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
| ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) << 6 );
destination[ destOffset ] = (byte)( outBuff >>> 16 );
destination[ destOffset + 1 ] = (byte)( outBuff >>> 8 );
return 2;
}
// Example: DkLE
else {
// Two ways to do the same thing. Don't know which way I like best.
//int outBuff = ( ( DECODABET[ source[ srcOffset ] ] << 24 ) >>> 6 )
// | ( ( DECODABET[ source[ srcOffset + 1 ] ] << 24 ) >>> 12 )
// | ( ( DECODABET[ source[ srcOffset + 2 ] ] << 24 ) >>> 18 )
// | ( ( DECODABET[ source[ srcOffset + 3 ] ] << 24 ) >>> 24 );
int outBuff = ( ( DECODABET[ source[ srcOffset ] ] & 0xFF ) << 18 )
| ( ( DECODABET[ source[ srcOffset + 1 ] ] & 0xFF ) << 12 )
| ( ( DECODABET[ source[ srcOffset + 2 ] ] & 0xFF ) << 6)
| ( ( DECODABET[ source[ srcOffset + 3 ] ] & 0xFF ) );
destination[ destOffset ] = (byte)( outBuff >> 16 );
destination[ destOffset + 1 ] = (byte)( outBuff >> 8 );
destination[ destOffset + 2 ] = (byte)( outBuff );
return 3;
}
} // end decodeToBytes
/**
* Low-level access to decoding ASCII characters in
* the form of a byte array. Ignores GUNZIP option, if
* it's set. This is not generally a recommended method,
* although it is used internally as part of the decoding process.
* Special case: if len = 0, an empty array is returned. Still,
* if you need more speed and reduced memory footprint (and aren't
* gzipping), consider this method.
*
* @param source The Base64 encoded data
* @return decoded data
* @since 2.3.1
*/
public static byte[] decode( byte[] source )
throws java.io.IOException {
return decode( source, 0, source.length);
}
/**
* Low-level access to decoding ASCII characters in
* the form of a byte array. Ignores GUNZIP option, if
* it's set. This is not generally a recommended method,
* although it is used internally as part of the decoding process.
* Special case: if len = 0, an empty array is returned. Still,
* if you need more speed and reduced memory footprint (and aren't
* gzipping), consider this method.
*
* @param source The Base64 encoded data
* @param off The offset of where to begin decoding
* @param len The length of characters to decode
* @return decoded data
* @throws java.io.IOException If bogus characters exist in source data
* @since 1.3
*/
@SuppressWarnings("cast")
public static byte[] decode( byte[] source, int off, int len)
throws java.io.IOException {
// Lots of error checking and exception throwing
if( source == null ){
throw new NullPointerException( "Cannot decode null source array." );
} // end if
if( off < 0 || off + len > source.length ){
throw new IllegalArgumentException( String.format(
"Source array with length %d cannot have offset of %d and process %d bytes.", source.length, off, len ) );
} // end if
if( len == 0 ){
return new byte[0];
}else if( len < 4 ){
throw new IllegalArgumentException(
"Base64-encoded string must have at least four characters, but length specified was " + len );
} // end if
int len34 = len * 3 / 4; // Estimate on array size
byte[] outBuff = new byte[ len34 ]; // Upper limit on size of output
int outBuffPosn = 0; // Keep track of where we're writing
byte[] b4 = new byte[4]; // Four byte buffer from source, eliminating white space
int b4Posn = 0; // Keep track of four byte input buffer
int i = 0; // Source array counter
byte sbiDecode = 0; // Special value from DECODABET
for( i = off; i < off+len; i++ ) { // Loop through source
sbiDecode = DECODABET[ source[i]&0xFF ];
// White space, Equals sign, or legit Base64 character
// Note the values such as -5 and -9 in the
// DECODABETs at the top of the file.
if( sbiDecode >= WHITE_SPACE_ENC ) {
if( sbiDecode >= EQUALS_SIGN_ENC ) {
b4[ b4Posn++ ] = source[i]; // Save non-whitespace
if( b4Posn > 3 ) { // Time to decode?
outBuffPosn += decode4to3( b4, 0, outBuff, outBuffPosn);
b4Posn = 0;
// If that was the equals sign, break out of 'for' loop
if( source[i] == EQUALS_SIGN ) {
break;
} // end if: equals sign
} // end if: quartet built
} // end if: equals sign or better
} // end if: white space, equals sign or better
else {
// There's a bad input character in the Base64 stream.
throw new java.io.IOException( String.format(
"Bad Base64 input character decimal %d in array position %d", ((int)source[i])&0xFF, i ) );
} // end else:
} // each input character
byte[] out = new byte[ outBuffPosn ];
System.arraycopy( outBuff, 0, out, 0, outBuffPosn );
return out;
} // end decode
} // end class Base64© 2015 - 2024 Weber Informatics LLC | Privacy Policy