question: public static byte [ ] decode ( String data ) { ByteArrayOutputStream bOut = new ByteArrayOutputStream ( ) ; try { encoder . decode ( data , bOut ) ; } catch ( Exception e ) { throw new DecoderException ( "exception decoding URL safe base64 string: " + e . getMessage ( ) , e ) ; } return bOut . toByteArray ( ) ; }
target:  decode the URL safe base 64 encoded String data - whitespace will be ignored.