com.lowagie.text.pdf.codec
Class Base64

java.lang.Object
  com.lowagie.text.pdf.codec.Base64

public class Base64
extends Object

Encodes and decodes to and from Base64 notation.

Homepage: http://iharder.net/base64.

Change Log:

• 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:
  1. The default is RFC3548 format.
  2. 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
  3. 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.

Version:

2.2.1

Author:

Robert Harder, rob@iharder.net

Nested Class Summary

static class	Base64.InputStream A Base64.InputStream will read data from another java.io.InputStream, given in the constructor, and encode/decode to/from Base64 notation on the fly.
static class	Base64.OutputStream A Base64.OutputStream will write data to another java.io.OutputStream, given in the constructor, and encode/decode to/from Base64 notation on the fly.

Field Summary

private static byte[]	_ORDERED_ALPHABET I don't get the point of this technique, but it is described here: http://www.faqs.org/qa/rfcc-1940.html.
private static byte[]	_ORDERED_DECODABET Used in decoding the "ordered" dialect of Base64.
private static byte[]	_STANDARD_ALPHABET The 64 valid Base64 values.
private static byte[]	_STANDARD_DECODABET Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.
private static byte[]	_URL_SAFE_ALPHABET Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html.
private static byte[]	_URL_SAFE_DECODABET Used in decoding URL- and Filename-safe dialects of Base64.
static int	DECODE Specify decoding.
static int	DONT_BREAK_LINES Don't break lines when encoding (violates strict Base64 specification)
static int	ENCODE Specify encoding.
private static byte	EQUALS_SIGN The equals sign (=) as a byte.
private static byte	EQUALS_SIGN_ENC
static int	GZIP Specify that data should be gzip-compressed.
private static int	MAX_LINE_LENGTH Maximum line length (76) of Base64 output.
private static byte	NEW_LINE The new line character (\n) as a byte.
static int	NO_OPTIONS No options specified.
static int	ORDERED Encode using the special "ordered" dialect of Base64 described here: http://www.faqs.org/qa/rfcc-1940.html.
private static String	PREFERRED_ENCODING Preferred encoding.
static int	URL_SAFE Encode using Base64-like encoding that is URL- and Filename-safe as described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html.
private static byte	WHITE_SPACE_ENC

Constructor Summary

private

Base64() Defeats instantiation.

Method Summary

static byte[]	decode(byte[] source, int off, int len, int options) Very low-level access to decoding ASCII characters in the form of a byte array.
static byte[]	decode(String s) Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
static byte[]	decode(String s, int options) Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
private static int	decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset, int options) Decodes four bytes from array source and writes the resulting bytes (up to three of them) to destination.
static void	decodeFileToFile(String infile, String outfile) Reads infile and decodes it to outfile.
static byte[]	decodeFromFile(String filename) Convenience method for reading a base64-encoded file and decoding it.
static boolean	decodeToFile(String dataToDecode, String filename) Convenience method for decoding data to a file.
static Object	decodeToObject(String encodedObject) Attempts to decode Base64 data and deserialize a Java Object within.
private static byte[]	encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes, int options) Encodes up to the first three bytes of array threeBytes and returns a four-byte array in Base64 notation.
private static byte[]	encode3to4(byte[] source, int srcOffset, int numSigBytes, byte[] destination, int destOffset, int options) Encodes up to three bytes of the array source and writes the resulting four Base64 bytes to destination.
static String	encodeBytes(byte[] source) Encodes a byte array into Base64 notation.
static String	encodeBytes(byte[] source, int options) Encodes a byte array into Base64 notation.
static String	encodeBytes(byte[] source, int off, int len) Encodes a byte array into Base64 notation.
static String	encodeBytes(byte[] source, int off, int len, int options) Encodes a byte array into Base64 notation.
static void	encodeFileToFile(String infile, String outfile) Reads infile and encodes it to outfile.
static String	encodeFromFile(String filename) Convenience method for reading a binary file and base64-encoding it.
static String	encodeObject(Serializable serializableObject) Serializes an object and returns the Base64-encoded version of that serialized object.
static String	encodeObject(Serializable serializableObject, int options) Serializes an object and returns the Base64-encoded version of that serialized object.
static boolean	encodeToFile(byte[] dataToEncode, String filename) Convenience method for encoding data to a file.
private static byte[]	getAlphabet(int options) Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options specified.
private static byte[]	getDecodabet(int options) Returns one of the _SOMETHING_DECODABET byte arrays depending on the options specified.
static void	main(String[] args) Encodes or decodes two files from the command line; feel free to delete this method (in fact you probably should) if you're embedding this code into a larger program.
private static void	usage(String msg) Prints command line usage.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

NO_OPTIONS

public static final int NO_OPTIONS

No options specified. Value is zero.

See Also:

Constant Field Values

ENCODE

public static final int ENCODE

Specify encoding.

See Also:

Constant Field Values

DECODE

public static final int DECODE

Specify decoding.

See Also:

Constant Field Values

GZIP

public static final int GZIP

Specify that data should be gzip-compressed.

See Also:

Constant Field Values

DONT_BREAK_LINES

public static final int DONT_BREAK_LINES

Don't break lines when encoding (violates strict Base64 specification)

See Also:

Constant Field Values

URL_SAFE

public static final int URL_SAFE

Encode using Base64-like encoding that is URL- and Filename-safe as described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html. It is important to note that data encoded this way is not officially valid Base64, or at the very least should not be called Base64 without also specifying that is was encoded using the URL- and Filename-safe dialect.

See Also:

Constant Field Values

ORDERED

public static final int ORDERED

Encode using the special "ordered" dialect of Base64 described here: http://www.faqs.org/qa/rfcc-1940.html.

See Also:

Constant Field Values

MAX_LINE_LENGTH

private static final int MAX_LINE_LENGTH

Maximum line length (76) of Base64 output.

See Also:

Constant Field Values

EQUALS_SIGN

private static final byte EQUALS_SIGN

The equals sign (=) as a byte.

See Also:

Constant Field Values

NEW_LINE

private static final byte NEW_LINE

The new line character (\n) as a byte.

See Also:

Constant Field Values

PREFERRED_ENCODING

private static final String PREFERRED_ENCODING

Preferred encoding.

See Also:

Constant Field Values

WHITE_SPACE_ENC

private static final byte WHITE_SPACE_ENC

See Also:

Constant Field Values

EQUALS_SIGN_ENC

private static final byte EQUALS_SIGN_ENC

See Also:

Constant Field Values

_STANDARD_ALPHABET

private static final byte[] _STANDARD_ALPHABET

The 64 valid Base64 values.

_STANDARD_DECODABET

private static final byte[] _STANDARD_DECODABET

Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.

_URL_SAFE_ALPHABET

private static final byte[] _URL_SAFE_ALPHABET

Used in the URL- and Filename-safe dialect described in Section 4 of RFC3548: http://www.faqs.org/rfcs/rfc3548.html. Notice that the last two bytes become "hyphen" and "underscore" instead of "plus" and "slash."

_URL_SAFE_DECODABET

private static final byte[] _URL_SAFE_DECODABET

Used in decoding URL- and Filename-safe dialects of Base64.

_ORDERED_ALPHABET

private static final byte[] _ORDERED_ALPHABET

I don't get the point of this technique, but it is described here: http://www.faqs.org/qa/rfcc-1940.html.

_ORDERED_DECODABET

private static final byte[] _ORDERED_DECODABET

Used in decoding the "ordered" dialect of Base64.

Constructor Detail

Base64

private Base64()

Defeats instantiation.

Method Detail

getAlphabet

private static final byte[] getAlphabet(int options)

Returns one of the _SOMETHING_ALPHABET byte arrays depending on the options specified. It's possible, though silly, to specify ORDERED and URLSAFE in which case one of them will be picked, though there is no guarantee as to which one will be picked.

getDecodabet

private static final byte[] getDecodabet(int options)

Returns one of the _SOMETHING_DECODABET byte arrays depending on the options specified. It's possible, though silly, to specify ORDERED and URL_SAFE in which case one of them will be picked, though there is no guarantee as to which one will be picked.

main

public static final void main(String[] args)

Encodes or decodes two files from the command line; feel free to delete this method (in fact you probably should) if you're embedding this code into a larger program.

usage

private static final void usage(String msg)

Prints command line usage.

Parameters:

msg - A message to include with usage info.

encode3to4

private static byte[] encode3to4(byte[] b4,
                                 byte[] threeBytes,
                                 int numSigBytes,
                                 int options)

Encodes up to the first three bytes of array threeBytes and returns a four-byte array in Base64 notation. The actual number of significant bytes in your array is given by numSigBytes. The array threeBytes needs only be as big as numSigBytes. Code can reuse a byte array by passing a four-byte array as b4.

Parameters:

b4 - A reusable byte array to reduce array instantiation

threeBytes - the array to convert

numSigBytes - the number of significant bytes in your array

Returns:

four byte array in Base64 notation.

Since:

1.5.1

encode3to4

private static byte[] encode3to4(byte[] source,
                                 int srcOffset,
                                 int numSigBytes,
                                 byte[] destination,
                                 int destOffset,
                                 int options)

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.

Parameters:

source - the array to convert

srcOffset - the index where conversion begins

numSigBytes - the number of significant bytes in your array

destination - the array to hold the conversion

destOffset - the index where output will be put

Returns:

the destination array

Since:

1.3

encodeObject

public static String encodeObject(Serializable serializableObject)

Serializes an object and returns the Base64-encoded version of that serialized object. If the object cannot be serialized or there is another error, the method will return null. The object is not GZip-compressed before being encoded.

Parameters:

serializableObject - The object to encode

Returns:

The Base64-encoded object

Since:

1.4

encodeObject

public static String encodeObject(Serializable serializableObject,
                                  int options)

Serializes an object and returns the Base64-encoded version of that serialized object. If the object cannot be serialized or there is another error, the method will return null.

Valid options:

   GZIP: gzip-compresses object before encoding it.
   DONT_BREAK_LINES: don't break lines at 76 characters
     Note: Technically, this makes your encoding non-compliant.
 

Example: encodeObject( myObj, Base64.GZIP ) or

Example: encodeObject( myObj, Base64.GZIP | Base64.DONT_BREAK_LINES )

Parameters:

serializableObject - The object to encode

options - Specified options

Returns:

The Base64-encoded object

Since:

2.0

See Also:

GZIP, DONT_BREAK_LINES

encodeBytes

public static String encodeBytes(byte[] source)

Encodes a byte array into Base64 notation. Does not GZip-compress data.

Parameters:

source - The data to convert

Since:

1.4

encodeBytes

public static String encodeBytes(byte[] source,
                                 int options)

Encodes a byte array into Base64 notation.

Valid options:

   GZIP: gzip-compresses object before encoding it.
   DONT_BREAK_LINES: don't break lines at 76 characters
     Note: Technically, this makes your encoding non-compliant.
 

Example: encodeBytes( myData, Base64.GZIP ) or

Example: encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )

Parameters:

source - The data to convert

options - Specified options

Since:

2.0

See Also:

GZIP, DONT_BREAK_LINES

encodeBytes

public static String encodeBytes(byte[] source,
                                 int off,
                                 int len)

Encodes a byte array into Base64 notation. Does not GZip-compress data.

Parameters:

source - The data to convert

off - Offset in array where conversion should begin

len - Length of data to convert

Since:

1.4

encodeBytes

public static String encodeBytes(byte[] source,
                                 int off,
                                 int len,
                                 int options)

Encodes a byte array into Base64 notation.

Valid options:

   GZIP: gzip-compresses object before encoding it.
   DONT_BREAK_LINES: don't break lines at 76 characters
     Note: Technically, this makes your encoding non-compliant.
 

Example: encodeBytes( myData, Base64.GZIP ) or

Example: encodeBytes( myData, Base64.GZIP | Base64.DONT_BREAK_LINES )

Parameters:

source - The data to convert

off - Offset in array where conversion should begin

len - Length of data to convert

options - Specified options alphabet type is pulled from this (standard, url-safe, ordered)

Since:

2.0

See Also:

GZIP, DONT_BREAK_LINES

decode4to3

private static int decode4to3(byte[] source,
                              int srcOffset,
                              byte[] destination,
                              int destOffset,
                              int options)

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.

Parameters:

source - the array to convert

srcOffset - the index where conversion begins

destination - the array to hold the conversion

destOffset - the index where output will be put

options - alphabet type is pulled from this (standard, url-safe, ordered)

Returns:

the number of decoded bytes converted

Since:

1.3

decode

public static byte[] decode(byte[] source,
                            int off,
                            int len,
                            int options)

Very low-level access to decoding ASCII characters in the form of a byte array. Does not support automatically gunzipping or any other "fancy" features.

Parameters:

source - The Base64 encoded data

off - The offset of where to begin decoding

len - The length of characters to decode

Returns:

decoded data

Since:

1.3

decode

public static byte[] decode(String s)

Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.

Parameters:

s - the string to decode

Returns:

the decoded data

Since:

1.4

decode

public static byte[] decode(String s,
                            int options)

Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.

Parameters:

s - the string to decode

options - encode options such as URL_SAFE

Returns:

the decoded data

Since:

1.4

decodeToObject

public static Object decodeToObject(String encodedObject)

Attempts to decode Base64 data and deserialize a Java Object within. Returns null if there was an error.

Parameters:

encodedObject - The Base64 data to decode

Returns:

The decoded and deserialized object

Since:

1.5

encodeToFile

public static boolean encodeToFile(byte[] dataToEncode,
                                   String filename)

Convenience method for encoding data to a file.

Parameters:

dataToEncode - byte array of data to encode in base64 form

filename - Filename for saving encoded data

Returns:

true if successful, false otherwise

Since:

2.1

decodeToFile

public static boolean decodeToFile(String dataToDecode,
                                   String filename)

Convenience method for decoding data to a file.

Parameters:

dataToDecode - Base64-encoded data as a string

filename - Filename for saving decoded data

Returns:

true if successful, false otherwise

Since:

2.1

decodeFromFile

public static byte[] decodeFromFile(String filename)

Convenience method for reading a base64-encoded file and decoding it.

Parameters:

filename - Filename for reading encoded data

Returns:

decoded byte array or null if unsuccessful

Since:

2.1

encodeFromFile

public static String encodeFromFile(String filename)

Convenience method for reading a binary file and base64-encoding it.

Parameters:

filename - Filename for reading binary data

Returns:

base64-encoded string or null if unsuccessful

Since:

2.1

encodeFileToFile

public static void encodeFileToFile(String infile,
                                    String outfile)

Reads infile and encodes it to outfile.

Parameters:

infile - Input file

outfile - Output file

Since:

2.2

decodeFileToFile

public static void decodeFileToFile(String infile,
                                    String outfile)

Reads infile and decodes it to outfile.

Parameters:

infile - Input file

outfile - Output file

Since:

2.2