Class Base64


  • public class Base64
    extends java.lang.Object

    This code is a stripped down version of Robert Harder's Public Domain Base64 implementation. GZIP support, InputStream and OutputStream stuff and some unneeded encode/decode methods have been removed.

    -- Original comments follow --

    Encodes and decodes to and from Base64 notation.

    Change Log:

    • 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:
    2.1
    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static byte[] _NATIVE_ALPHABET  
      private static byte[] ALPHABET
      The 64 valid Base64 values.
      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  
      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

      Constructors 
      Modifier Constructor Description
      private Base64()
      Defeats instantiation.
    • Method Summary

      All Methods Static Methods Concrete Methods 
      Modifier and Type Method Description
      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 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.
      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.
      • 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
      • 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.
    • Constructor Detail

      • Base64

        private Base64()
        Defeats instantiation.
    • Method Detail

      • 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 accommodate 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
      • 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
        Returns:
        Base64 notation of input data
        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
        Returns:
        Base64 notation
        Since:
        2.0
        See Also:
        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
        Returns:
        Base64 notation
        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
        Returns:
        Base64 notation
        Since:
        2.0
        See Also:
        DONT_BREAK_LINES
      • 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 accommodate 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