how to get an object an invoke a method in jstl EL in a JSP

Question

I'm trying to convert the following scriptlet code to EL. I tried the following (below), but can't get it working. getValue() is a method off of ConfigFactory that returns a string:

In a listener, I set the configFactory as event.getServletContext().setAttribute("ConfigFactory", new ConfigFactory());

In my scriptlet code there is: (and it works fine)

<% 
  ConfigFactory cf = (ConfigFactory) application.getAttribute("ConfigFactory");
%>
Value from scriptlet= <%=cf.getValue()%> <br/>

EL gives me trouble:

<c:set var="cf" value="${initParam['ConfigFactory']}"/>
<c:out value="${cf.getValue}"/>  <!-- try # 1 -->
<c:out value="${cf.value}"/>     <!-- try # 2 -->

Answer 1

Not tested: ${applicationScope.ConfigFactory.value}

Answer 2

This line

<c:set var="cf" value="${initParam['ConfigFactory']}"/>

does basically the same as

pageContext.setAttribute("cf", application.getInitParameter("ConfigFactory"));

You don't want this. Get rid of that line. In EL, you have implicitly direct access to all request, session and application attributes by just its name. The following

${ConfigFactory}

does basically the same as

out.print(pageContext.findAttribute("ConfigFactory"));

The PageContext#findAttribute() tests respectively PageContext#getAttribute(), HttpServletRequest#getAttribute(), HttpSession#getAttribute() and finally ServletContext#getAttribute() until the first non-null value is been found. This is more what you want.

You can finally access the getValue() method on it the usual EL way:

${ConfigFactory.value}

Not related to the problem, but you'd normally give instance identifiers a name starting with lowercase. You also don't do ConfigFactory ConfigFactory = new ConfigFactory();, right? :)