If you require a webapp to always run in https mode using a SSL key, then you need to add the following to your WEB-INF/web.xml configuration.

 <security-constraint>
    <web-resource-collection>
        <web-resource-name>jsp</web-resource-name>
        <url-pattern>*.htm</url-pattern>
        <url-pattern>*.html</url-pattern>
    </web-resource-collection>
    <user-data-constraint>
        <transport-guarantee>CONFIDENTIAL</transport-guarantee>
    </user-data-constraint>
</security-constraint>