Authorization check for links on a page

Question

We are trying to control whether links on a JSP page are displayed or hidden based on an authorization check.
We've already got the checks working on individual pages but not for the links within a page, because the security framework does not list links as their own Resource.
Is there a way to call the Authorization security provider ourselves, for each link on our JSPs? This call would be outside of the initial security check for the main JSP.

Answer 1

It's not going to be easy without DOM. Parsing HTML is a real pain, since there's all kinds of optional tags and quotation marks (pre-XHTML, that is). That makes any kind of ad-hoc parsing using regular expressions difficult, and less accurate than pulling the entire file into a DOM representation.
Why don't you want to use DOM? Are you just making up silly requirements?
EDIT:
I guess you could use an event-based HTML parser (HTML::Parser in Perl works this way. Is there a Java equivalent?) Set up an event for IMG and A start tags, and extract the href/src attributes there. Finding out if they are valid or not will require either:
1) Simply validate that the URL is well-formed by creating a URL object from it. This won't tell you if the link is active or not
2) Validate the URL by connecting to it with an URLConnection. However, the URL will be marked invalid if the server is down or the URL is otherwise unavailable.
Brian
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