It's completely backwards, and it should be obvious it looks like no other JSP tag you've ever used.
<s:a href="http://localhost:8080/MyStruts2/bloggingns/ShowBlogAdminPage">
Admin Page
</s:a>
Unrelated, but if this is an internal link, e.g., within the same site, it makes zero sense to use (a) the full URL, it's an action, and (b) the <s:a>
tag at all. Prefer:
<a href="<s:url action='ShowBlogAdminPage' />">Admin Page</a>