Custom JSP taglib. This lets you check ISBN value. For example:

<%@ taglib uri="taglib.tld" prefix="i" %>

<i:validISBN isbn="5-94278-605-4">
   valid ISBN code
</i:validISBN>

Tags are:

validISBN

Body tag executes own body if parameter presents a valid ISBN. Parameters are:

1) isbn Describes a string with ISBN

notValidISBN

Body tag executes own body if parameter does not present a valid ISBN. Parameters are:

1) isbn Describes a string with ISBN

for downloading:

Library: isbntag.jar    Description: taglib.tld

© Coldbeans      Comments?

See also Coldtags suite - the largest collection of custom JSP tags.