private String fileExt ( String url ) { if ( url . indexOf ( "?" ) > - 1 ) { url = url . substring ( 0 , url . indexOf ( "?" ) ) ; } if ( url . lastIndexOf ( "." ) == - 1 ) { return null ; } else { String ext = url . substring ( url . lastIndexOf ( "." ) ) ; if ( ext . indexOf ( "%" ) > - 1 ) { ext = ext . substring ( 0 , ext . indexOf ( "%" ) ) ; } if ( ext . indexOf ( "/" ) > - 1 ) { ext = ext . substring ( 0 , ext . indexOf ( "/" ) ) ; } return ext . toLowerCase ( ) ; } }
Returns the file extension of a file .