The question doesn't make much sense in the modern era where there should be no Java code in the JSP, so no opportunities for interfaces or any other Java concepts. The question is also too vague to understand what it means in the grand scheme of things.
There is an extends attribute of the page directive. You can implement a custom JSP page super class and use that class as the super class of your JSP. That class can implement the interface that you want. But as Bear said, this doesn't make much sense, who asked you this ??