Class Base64


  • public class Base64
    extends java.lang.Object
    Encodes and decodes to and from Base64 notation.

    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.

    • Field Summary

      Fields 
      Modifier and Type Field Description
      private static byte[] DEC
      Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning.
      private static byte[] ENC
      The 64 valid Base64 values.
      private static byte EQUALS_SIGN
      The equals sign (=) as a byte.
      private static byte EQUALS_SIGN_DEC
      Indicates equals sign in encoding.
      private static byte INVALID_DEC
      Indicates an invalid byte during decoding.
      private static byte WHITE_SPACE_DEC
      Indicates white space in encoding.
    • 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)
      Low-level decoding ASCII characters from a byte array.
      static byte[] decode​(java.lang.String s)
      Decodes data from Base64 notation.
      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 void 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 off, int len)
      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

      • EQUALS_SIGN

        private static final byte EQUALS_SIGN
        The equals sign (=) as a byte.
        See Also:
        Constant Field Values
      • EQUALS_SIGN_DEC

        private static final byte EQUALS_SIGN_DEC
        Indicates equals sign in encoding.
        See Also:
        Constant Field Values
      • WHITE_SPACE_DEC

        private static final byte WHITE_SPACE_DEC
        Indicates white space in encoding.
        See Also:
        Constant Field Values
      • INVALID_DEC

        private static final byte INVALID_DEC
        Indicates an invalid byte during decoding.
        See Also:
        Constant Field Values
      • ENC

        private static final byte[] ENC
        The 64 valid Base64 values.
      • DEC

        private static final byte[] DEC
        Translates a Base64 value to either its 6-bit reconstruction value or a negative number indicating some other meaning. The table is only 7 bits wide, as the 8th bit is discarded during decoding.
    • Constructor Detail

      • Base64

        private Base64()
        Defeats instantiation.
    • Method Detail

      • encode3to4

        private static void 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
      • encodeBytes

        public static java.lang.String encodeBytes​(byte[] source)
        Encodes a byte array into Base64 notation.
        Parameters:
        source - The data to convert
        Returns:
        encoded base64 representation of source.
      • 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
        Returns:
        encoded base64 representation of source.
      • 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
      • decode

        public static byte[] decode​(byte[] source,
                                    int off,
                                    int len)
        Low-level decoding ASCII characters from a 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
        Throws:
        java.lang.IllegalArgumentException - the input is not a valid Base64 sequence.
      • decode

        public static byte[] decode​(java.lang.String s)
        Decodes data from Base64 notation.
        Parameters:
        s - the string to decode
        Returns:
        the decoded data