public static String getMimeTypeForFile ( URL url ) { if ( url == null ) { //The input url is null so we can't retrieve a mimetype, therefore we return null. return null ; } String external = url . toExternalForm ( ) ; if ( external . indexOf ( ' ' ) == - 1 ) { return BINARY ; } else { String ext = external . substring ( external . lastIndexOf ( ' ' ) + 1 ) ; String mime = KnownMimeTypes . getMimeTypeByExtension ( ext ) ; if ( mime == null ) { return BINARY ; } else { return mime ; } } }
Makes an educated guess of the mime type of the resource pointed by this url . It tries to extract an extension part and confronts this extension to the list of known extensions .