edu.nyu.cs.pdsg.util
Class Base64

java.lang.Object
  extended byedu.nyu.cs.pdsg.util.Base64

public class Base64
extends java.lang.Object

Encodes and decodes to and from Base64 notation.

Change Log:

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/xmlizable periodically to check for updates or to contribute improvements.

Version:
1.4
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[] ALPHABET
          The 64 valid Base64 values.
private static byte BAD_ENCODING
           
static boolean COMPRESS
          Specify that data should be compressed (value is true).
private static byte[] DECODABET
          Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.
static boolean DECODE
          Specify decoding (value is false).
static boolean DONT_COMPRESS
          Specify that data should not be compressed (value is false).
static boolean ENCODE
          Specify encoding (value is true).
private static byte EQUALS_SIGN
          The equals sign (=) as a byte.
private static byte EQUALS_SIGN_ENC
           
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.
private static byte WHITE_SPACE_ENC
           
 
Constructor Summary
private Base64()
          Defeats instantiation.
 
Method Summary
static byte[] decode(byte[] source, int off, int len)
          Decodes Base64 content in byte array format and returns the decoded byte array.
static byte[] decode(java.lang.String s)
          Decodes data from Base64 notation.
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 byte[] decodeFromFile(java.lang.String encfile)
          Simple helper method that Base64-decodes a file and returns the decoded data or null if there was an error.
static boolean decodeToFile(byte[] encdata, java.lang.String file)
          Simple helper method that Base64-decodes data to a file.
static java.lang.Object decodeToObject(java.lang.String encodedObject)
          Attempts to decode Base64 data and deserialize a Java Object within.
static java.lang.String decodeToString(java.lang.String s)
          Decodes data from Base64 notation and returns it as a string.
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[] 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, boolean breakLines)
          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, boolean breakLines)
          Encodes a byte array into Base64 notation.
static java.lang.String encodeFromFile(java.lang.String rawfile)
          Simple helper method that Base64-encodes a file and returns the encoded string or null if there was an error.
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, boolean breakLines)
          Serializes an object and returns the Base64-encoded version of that serialized object.
static java.lang.String encodeString(java.lang.String s)
          Encodes a string in Base64 notation with line breaks after every 75 Base64 characters.
static java.lang.String encodeString(java.lang.String s, boolean breakLines)
          Encodes a string in Base64 notation with line breaks after every 75 Base64 characters.
static boolean encodeToFile(byte[] rawdata, java.lang.String file)
          Simple helper method that Base64-encodes data to a file.
static void main(java.lang.String[] args)
          Testing.
static byte[] readFile(java.io.File file, boolean encode)
          Reads a file and either encodes or decodes it.
static byte[] readFile(java.lang.String file, boolean encode)
          Reads a file and either encodes or decodes it.
static boolean writeFile(byte[] data, java.io.File file, boolean encode)
          Writes a byte array to a file either encoding it or decoding it as specified.
static boolean writeFile(byte[] data, int offset, int length, java.io.File file, boolean encode)
          Writes a byte array to a file either encoding it or decoding it as specified.
static boolean writeFile(byte[] data, java.lang.String file, boolean encode)
          Writes a byte array to a file either encoding it or decoding it as specified.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

ENCODE

public static final boolean ENCODE
Specify encoding (value is true).

See Also:
Constant Field Values

DECODE

public static final boolean DECODE
Specify decoding (value is false).

See Also:
Constant Field Values

COMPRESS

public static final boolean COMPRESS
Specify that data should be compressed (value is true).

See Also:
Constant Field Values

DONT_COMPRESS

public static final boolean DONT_COMPRESS
Specify that data should not be compressed (value is false).

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

ALPHABET

private static final byte[] ALPHABET
The 64 valid Base64 values.


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

main

public static void main(java.lang.String[] args)
Testing. Feel free--in fact I encourage you--to throw out this entire "main" method when you actually deploy this code.


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[] 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.

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,
                                            boolean breakLines)
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.

Parameters:
serializableObject - The object to encode
breakLines - Break lines at 80 characters or less.
Returns:
The Base64-encoded object
Since:
1.4

encodeBytes

public static java.lang.String encodeBytes(byte[] source)
Encodes a byte array into Base64 notation. Equivalen to calling encodeBytes( source, 0, source.length )

Parameters:
source - The data to convert
Since:
1.4

encodeBytes

public static java.lang.String encodeBytes(byte[] source,
                                           boolean breakLines)
Encodes a byte array into Base64 notation. Equivalen to calling encodeBytes( source, 0, source.length )

Parameters:
source - The data to convert
breakLines - Break lines at 80 characters or less.
Since:
1.4

encodeBytes

public static java.lang.String encodeBytes(byte[] source,
                                           int off,
                                           int len)
Encodes a byte array into Base64 notation.

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,
                                           boolean breakLines)
Encodes a byte array into Base64 notation.

Parameters:
source - The data to convert
off - Offset in array where conversion should begin
len - Length of data to convert
breakLines - Break lines at 80 characters or less.
Since:
1.4

encodeString

public static java.lang.String encodeString(java.lang.String s)
Encodes a string in Base64 notation with line breaks after every 75 Base64 characters. Of course you probably only need to encode a string if there are non-ASCII characters in it such as many non-English languages.

Parameters:
s - the string to encode
Returns:
the encoded string
Since:
1.3

encodeString

public static java.lang.String encodeString(java.lang.String s,
                                            boolean breakLines)
Encodes a string in Base64 notation with line breaks after every 75 Base64 characters. Of course you probably only need to encode a string if there are non-ASCII characters in it such as many non-English languages.

Parameters:
s - the string to encode
breakLines - Break lines at 80 characters or less.
Returns:
the encoded string
Since:
1.3

readFile

public static byte[] readFile(java.lang.String file,
                              boolean encode)
Reads a file and either encodes or decodes it.

Parameters:
file - The file to read
encode - Whether or not to encode file as it is read.
Returns:
The encoded/decoded file or null if there was an error.
Since:
1.4

readFile

public static byte[] readFile(java.io.File file,
                              boolean encode)
Reads a file and either encodes or decodes it.

Parameters:
file - The file to read
encode - Whether or not to encode file as it is read.
Returns:
The encoded/decoded file or null if there was an error.
Since:
1.4

writeFile

public static boolean writeFile(byte[] data,
                                java.lang.String file,
                                boolean encode)
Writes a byte array to a file either encoding it or decoding it as specified.

Parameters:
data - The array to write to a file.
file - The file to write to.
encode - Whether or not to encode the data.
Returns:
Whether or not the write was a success.
Since:
1.4

writeFile

public static boolean writeFile(byte[] data,
                                java.io.File file,
                                boolean encode)
Writes a byte array to a file either encoding it or decoding it as specified.

Parameters:
data - The array to write to a file.
file - The file to write to.
encode - Whether or not to encode the data.
Returns:
Whether or not the write was a success.
Since:
1.4

writeFile

public static boolean writeFile(byte[] data,
                                int offset,
                                int length,
                                java.io.File file,
                                boolean encode)
Writes a byte array to a file either encoding it or decoding it as specified.

Parameters:
data - The array to write to a file.
offset - The offset where the "real" data begins.
length - The amount of data to write.
file - The file to write to.
encode - Whether or not to encode the data.
Returns:
Whether or not the write was a success.
Since:
1.4

encodeFromFile

public static java.lang.String encodeFromFile(java.lang.String rawfile)
Simple helper method that Base64-encodes a file and returns the encoded string or null if there was an error.

Parameters:
rawfile - The file to read
Returns:
The encoded file or null if there was an error.
Since:
1.4

decodeFromFile

public static byte[] decodeFromFile(java.lang.String encfile)
Simple helper method that Base64-decodes a file and returns the decoded data or null if there was an error.

Parameters:
encfile - The file to read
Returns:
The decoded file or null if there was an error.
Since:
1.4

encodeToFile

public static boolean encodeToFile(byte[] rawdata,
                                   java.lang.String file)
Simple helper method that Base64-encodes data to a file.

Parameters:
rawdata - The data to write.
file - The file to read.
Returns:
Whether or not the write was a success.
Since:
1.4

decodeToFile

public static boolean decodeToFile(byte[] encdata,
                                   java.lang.String file)
Simple helper method that Base64-decodes data to a file.

Parameters:
encdata - The data to write.
file - The file to read.
Returns:
Whether or not the write was a success.
Since:
1.4

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(java.lang.String s)
Decodes data from Base64 notation.

Parameters:
s - the string to decode
Returns:
the decoded data
Since:
1.4

decodeToString

public static java.lang.String decodeToString(java.lang.String s)
Decodes data from Base64 notation and returns it as a string. Equivlaent to calling new String( decode( s ) )

Parameters:
s - the strind to decode
Returns:
The data as a string
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:
1.4

decode

public static byte[] decode(byte[] source,
                            int off,
                            int len)
Decodes Base64 content in byte array format and returns the decoded byte array.

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


Copyright (c) 2002-2003 New York University RLAB