Base64 (XML Tree Object Model (XTOM))

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xtom.parser.util
Class Base64

java.lang.Object
  xtom.parser.util.Base64

public class Base64
extends java.lang.Object

Encodes and decodes to and from Base64 notation.

Change Log:

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:: 2.0
Author:: Robert Harder, rob@iharder.net

Nested Class Summary
`static class`	`Base64.InputStream` A `Base64#InputStream` will read data from another `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 `OutputStream`, given in the constructor, and encode/decode to/from Base64 notation on the fly.

Field Summary
`private static byte[]`	`_NATIVE_ALPHABET`
`private static byte[]`	`ALPHABET` The 64 valid Base64 values.
`private static byte`	`BAD_ENCODING`
`private static byte[]`	`DECODABET` Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.
`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.
`private static java.lang.String`	`PREFERRED_ENCODING` Preferred encoding.
`private static byte`	`WHITE_SPACE_ENC`

Constructor Summary
`private`	`Base64()` Defeats instantiation.

Method Summary
`static byte[]`	`decode(byte[] source, int off, int len)` Very low-level access to decoding ASCII characters in the form of a byte array.
`static byte[]`	`decode(java.lang.String s)` Decodes data from Base64 notation, automatically detecting gzip-compressed data and decompressing it.
`private static byte[]`	`decode4to3(byte[] fourBytes)` Decodes the first four bytes of array `fourBytes` and returns an array up to three bytes long with the decoded values.
`private static int`	`decode4to3(byte[] source, int srcOffset, byte[] destination, int destOffset)` Decodes four bytes from array `source` and writes the resulting bytes (up to three of them) to `destination`.
`static java.lang.Object`	`decodeToObject(java.lang.String encodedObject)` Attempts to decode Base64 data and deserialize a Java Object within.
`private static byte[]`	`encode3to4(byte[] threeBytes)` Encodes the first three bytes of array `threeBytes` and returns a four-byte array in Base64 notation.
`private static byte[]`	`encode3to4(byte[] b4, byte[] threeBytes, int numSigBytes)` Encodes up to the first three bytes of array `threeBytes` and returns a four-byte array in Base64 notation.
`private static byte[]`	`encode3to4(byte[] threeBytes, int numSigBytes)` 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)` Encodes up to three bytes of the array `source` and writes the resulting four Base64 bytes to `destination`.
`static java.lang.String`	`encodeBytes(byte[] source)` Encodes a byte array into Base64 notation.
`static java.lang.String`	`encodeBytes(byte[] source, int options)` Encodes a byte array into Base64 notation.
`static java.lang.String`	`encodeBytes(byte[] source, int off, int len)` Encodes a byte array into Base64 notation.
`static java.lang.String`	`encodeBytes(byte[] source, int off, int len, int options)` Encodes a byte array into Base64 notation.
`static java.lang.String`	`encodeObject(java.io.Serializable serializableObject)` Serializes an object and returns the Base64-encoded version of that serialized object.
`static java.lang.String`	`encodeObject(java.io.Serializable serializableObject, int options)` Serializes an object and returns the Base64-encoded version of that serialized object.

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

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 java.lang.String PREFERRED_ENCODING

Preferred encoding.

See Also:: Constant Field Values

ALPHABET

private static final byte[] ALPHABET

The 64 valid Base64 values.

_NATIVE_ALPHABET

private static final byte[] _NATIVE_ALPHABET

DECODABET

private static final byte[] DECODABET

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

BAD_ENCODING

private static final byte BAD_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

Constructor Detail

Base64

private Base64()

Defeats instantiation.

Method Detail

encode3to4

private static byte[] encode3to4(byte[] threeBytes)

Encodes the first three bytes of array threeBytes and returns a four-byte array in Base64 notation.

Parameters:: threeBytes - the array to convert
Returns:: four byte array in Base64 notation.
Since:: 1.3

encode3to4

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

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.

Parameters:: threeBytes - the array to convert; numSigBytes - the number of significant bytes in your array
Returns:: four byte array in Base64 notation.
Since:: 1.3

encode3to4

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

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)

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.

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 java.lang.String encodeObject(java.io.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 java.lang.String encodeObject(java.io.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
Returns:: The Base64-encoded object
Since:: 2.0
See Also:: GZIP, DONT_BREAK_LINES

encodeBytes

public static java.lang.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 java.lang.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 java.lang.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 java.lang.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
Since:: 2.0
See Also:: GZIP, DONT_BREAK_LINES

decode4to3

private static byte[] decode4to3(byte[] fourBytes)

Decodes the first four bytes of array fourBytes and returns an array up to three bytes long with the decoded values.

Parameters:: fourBytes - the array with Base64 content
Returns:: array with decoded values
Since:: 1.3

decode4to3

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

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.

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
Returns:: the number of decoded bytes converted
Since:: 1.3

decode

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

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(java.lang.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

decodeToObject

public static java.lang.Object decodeToObject(java.lang.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

Overview

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xtom.parser.util Class Base64

NO_OPTIONS

ENCODE

DECODE

GZIP

DONT_BREAK_LINES

MAX_LINE_LENGTH

EQUALS_SIGN

NEW_LINE

PREFERRED_ENCODING

ALPHABET

_NATIVE_ALPHABET

DECODABET

BAD_ENCODING

WHITE_SPACE_ENC

EQUALS_SIGN_ENC

Base64

encode3to4

encode3to4

encode3to4

encode3to4

encodeObject

encodeObject

encodeBytes

encodeBytes

encodeBytes

encodeBytes

decode4to3

decode4to3

decode

decode

decodeToObject

xtom.parser.util
Class Base64