public static boolean isAbsoluteUrl ( String url ) { if ( url == null ) { return false ; } final Pattern ABSOLUTE_URL = Pattern . compile ( "\\A[a-z0-9.+-]+://.*" , Pattern . CASE_INSENSITIVE ) ; return ABSOLUTE_URL . matcher ( url ) . matches ( ) ; }
Decides if a URL is absolute based on whether it contains a valid scheme name as defined in RFC 1738 .