com.revolsys.util

Class Base64

java.lang.Object

com.revolsys.util.Base64

public class Base64
extends Object

Encodes and decodes to and from Base64 notation.

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

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 (though that breaks strict Base64 compatibility), and encoding using the URL-safe and Ordered dialects.

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.DONT_BREAK_LINES );

to compress the data before encoding it and then making the output have no newline characters.

Change Log:

• v2.2.2 - Fixed encodeFileToFile and decodeFileToFile to use the Base64.InputStream class to encode and decode on the fly which uses less memory than encoding/decoding an entire file into memory before writing.
• 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:

2.2.2

Author:

Robert Harder, rob@iharder.net

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
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

Fields

Modifier and Type	Field and Description
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.
static int	GZIP Specify that data should be gzip-compressed.
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.
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.

Method Summary

Methods

Modifier and Type	Method and Description
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.
static byte[]	decodeBytesNoWrap(byte[] source)
static byte[]	decodeBytesNoWrap(String text)
static boolean	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.
static String	decodeToString(String string)
static String	encode(String string)
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 String	encodeBytesNoWrap(byte[] source)
static boolean	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.
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.

Methods inherited from class java.lang.Object

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

Field Detail

DECODE

public static final int DECODE

Specify decoding.

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

ENCODE

public static final int ENCODE

Specify encoding.

See Also:

Constant Field Values

GZIP

public static final int GZIP

Specify that data should be gzip-compressed.

See Also:

Constant Field Values

NO_OPTIONS

public static final int NO_OPTIONS

No options specified. Value is zero.

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

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

Method Detail

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

decodeBytesNoWrap

public static byte[] decodeBytesNoWrap(byte[] source)

decodeBytesNoWrap

public static byte[] decodeBytesNoWrap(String text)

decodeFileToFile

public static boolean decodeFileToFile(String infile,
                       String outfile)

Reads infile and decodes it to outfile.

Parameters:

infile - Input file

outfile - Output file

Returns:

true if the operation is successful

Since:

2.2

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

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

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

decodeToString

public static String decodeToString(String string)

encode

public static String encode(String string)

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
     <i>Note: Technically, this makes your encoding non-compliant.</i>
 

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
     <i>Note: Technically, this makes your encoding non-compliant.</i>
 

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

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

Since:

2.0

See Also:

GZIP, DONT_BREAK_LINES

encodeBytesNoWrap

public static String encodeBytesNoWrap(byte[] source)

encodeFileToFile

public static boolean encodeFileToFile(String infile,
                       String outfile)

Reads infile and encodes it to outfile.

Parameters:

infile - Input file

outfile - Output file

Returns:

true if the operation is successful

Since:

2.2

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

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
     <i>Note: Technically, this makes your encoding non-compliant.</i>
 

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

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

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.