Accessing Action class in JSP using Struts2

Question

Does anyone know how to easily access the Action class in a JSP when using Struts2? While I know it is often possible to use Struts tags and OGNL, I actually find them both to be confusing (clearly due to ignorance) and quite frankly find it easier to maintain Java in the JSP (not to mention it's easier to explain to new programmers as everyone knows Java).

I have searched for a solutions for years, and the best solution I have found is to call a static method from a class, that looks like:

public static BaseAction getCurrentAction(HttpServletRequest request) {
    OgnlValueStack ognlStack = (OgnlValueStack)request.getAttribute(org.apache.struts2.ServletActionContext.STRUTS_VALUESTACK_KEY);
    return (BaseAction)ognlStack.getRoot().get(0);
}

...which would be in a BaseAction class extended by you own Action class, so that in your JSP you can say:

<%
  MyAction action = (MyAction)BaseAction.getCurrentAction(request);
  String myValue = action.getMyValue();
%>

However this all seems overly complicated and it assumes a precise order in the OgnlValueStack - there must be a better way, non?

Many thanks for any advice!

Or ${myValue}. I find it nearly inconceivable that a tag, and even OGNL, is so difficult to understand that you'd resort to scriptlets. Are there specific things that cause you issues? If so, maybe it would make more sense to address that, than to try to figure out ways to write very suspicious code to do things trivially provided out-of-the-box. — Dave Newton
Thanks everyone! Clearly this is argumentative stuff, but it just feels easier and more natural to use scriptlets. ...and I'll admit ignorance - eg. I still don't understand when to use #, $ and % and the differences. Thing is, I get java as it's used everywhere else and I tend to be a fan of minimizing the number of technologies used in any given project in order to keep thing more simple. — Alex
A rough starter. Use # if the data you need is not in the action (IE the session), OGNL expressions aught to be wrapped with %{} but where an expression makes sense it isn't needed. ${} is an EL expression. Documentation is your friend: struts.apache.org/2.2.1.1/docs/tag-reference.html (There are plenty of examples you can even cut and paste your way though the simple stuff) — Quaternion
Many thanks Quanternion! I'm very familiar with that documentation and have gleaned knowledge for many of the examples - unless I'm figuratively blind (which may be possible) what is missing in that documentation is the rough starter knowledge you outline above. Thanks again! — Alex

Quaternion Quaternion · Accepted Answer · 2011-09-21T20:44:44

If you don't want to use struts2 tags an equally valid approach is to use JSTL tags. These tags are supported by struts2 and I'm guessing most major java web frameworks.

It is strongly recommended that you avoid servlets/scriplets in typical business programming using any Java Web Framework.

You probably already know this but to get a property from the action just say:

<s:property value="myProperty"/>

Or equally valid using the JSTL (some here would even say more valid as the view no longer depends on struts2)

<c:out value="${myProperty}" />

There are few programmers (and I would stand to say no seasoned struts2 programmers) who would find this harder to understand than

<%
  MyAction action = (MyAction)BaseAction.getCurrentAction(request);
  String myValue = action.getMyValue();
%>

There are only a handful of tags required to generate a page, you need to get properties, iterate to produce tables/lists and that's about it. The time learning those few tags will save a great deal of time.

Accessing Action class in JSP using Struts2

3 Answers