The joys of Try Catch (in a jsp)

This post is brought about after having Ninja come over and look at my code and making me realize that while what I was doing was good, I had not used a try catch and as such would never find exactly why my code was generating over 1500 lines of errors in my server log (ouch). Here is the way of Scriptlet (aka ninjascript) Try Catch-ery.

<% try { %>;
   <%-- code goes here --%>;
<% } catch (Exception e) {
   e.printStackTrace();
   Thread.sleep(20000); 
} %>;

You can further mod this to make it possibly more helpful by adding/replacing the last line so you end up with something like:

<% try { %>
   <%-- Code goes here --%>
<% } catch (Exception e) {
   System.out.println("Exception caught in NameOf.jsp");
   System.out.println(e.toString());
   e.printStackTrace();
} %>

Now for those people who are purists and understand that scriptlets really are not up to par, and that they are ugly and screw things up and are not elegant in the least, there is another way to Try Catch on your JSP. Simply use a JSTL Try Catch. Here I’ll set up an example:

   
      
   


   The exception is : ${catchException}


   There is an exception: ${catchException.message}

We set up a variable (catchException) and then what we want to do inside that c:catch. So we are trying to instantiate this bean and we want to make sure it doesn’t throw an error (which as part of the joys of websphere if that bean throws an error your page will fail and you’ll either get a portion of your page with nothing else, or you’ll get a series of dreaded CMNxxxx errors). Right after the c:catch block we set up a c:if with to test value of ${catchException, if it’s not empty, then an error was thrown and we should kick out what the error is so that we can fix it (without digging through 1500 lines of error-logged code).