JSP behavior - static initializer and jspInit

Question

In a recent discussion, the concept of using a static intializer in a JSP came up. The situtation was that someone had a series of Strings used in a single JSP and they wanted to #1, define these strings in the JSP itself (vs in web.xml or a resource file, which while preferable, was not really an item of discussion) and #2 wanted indexed access to the Strings (such as via a Map).
My thought was to declare the Map variable as static final in the JSP and then initialize it in a static initializer block with Map.put operations. Both the declaration of the Map and the static initializer block would be declared in a <%! %> declaration tag block. (The thought behind the static initialization - vs overriding jspInit - being that if multiple instances of the JSP were to be created, we wouldn't want to keep put'ing values into the Map for each new instance of the JSP.)
I built the following test scenario:
<<untitled3.jsp source>>
<%@ page import="java.util.*" %>
<%!
static final Map m = new HashMap();
static int staticCount = 0;
static int jspInitCount = 0;
static {
System.out.println("static initializer called");
staticCount++;
m.put("staticCount"+staticCount, "static# " + staticCount);
     public void jspInit() {
          super.jspInit();
jspInitCount++;
m.put("jspInitCount"+jspInitCount, "jspInit# " + jspInitCount);
System.out.println("overriden jspInit called:" + this);
%>
Map values:<br>
<%
Collection values = m.values();
Iterator i = values.iterator();
while (i.hasNext()) {
out.println(i.next().toString() + "<br>");
%>
Test
<<end of untitled3.jsp source>>
with the following web.xml entries:
<servlet>
<servlet-name>JSPServlet1</servlet-name>
<jsp-file>untitled3.jsp</jsp-file>
</servlet>
<servlet>
<servlet-name>JSPServlet2</servlet-name>
<jsp-file>untitled3.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>JSPServlet1</servlet-name>
<url-pattern>/jsp1</url-pattern>
</servlet-mapping>
<servlet-mapping>
<servlet-name>JSPServlet1</servlet-name>
<url-pattern>/jsp2</url-pattern>
</servlet-mapping>
I open a browser and request untitled3.jsp, I get the following output in the browser:
Map values:
static# 1
jspInit# 1
Test
with the following output to my JDeveloper (9.0.3.1) log window:
static initializer called
overriden jspInit called:_untitled3@61
I then request /jsp1 and get the following output in the browser:
Map values:
static# 1
jspInit# 2
jspInit# 1
Test
with the following output to my log window:
overriden jspInit called:_untitled3@63
Subsequent calls to /jsp1, /jsp2 or untitled3.jsp result in that same last output in the browser and no further output in the log window (ie, no further calls to the static initializer or jspInit method)
So, it appears that jspInit is being called once for the unmapped JSP request and one more time, the first time one of the web.xml-mapped JSP instances is requested. (I'd have thought that it would be called once for the /jsp1 request and once for the /jsp2 request...), but the static initializer is being called only once as expected.
Is this the correct behavior for the jspInit method? (ie, being called once for the unmapped request and once for the first mapped request?)
Also, if OC4J is used in a clustered/balanced configuration, is it possible that I'd end up with additional instances of my JSP in one or more JVMs?
Thanks!
Jim Stoll

Answer 1

You could scope such info to the application scope - some info is provided here: http://java.sun.com/products/jsp/tags/11/syntaxref11.fm14.html
"application - You can use the Bean from any JSP page in the same application as the JSP page that created the Bean. The Bean exists across an entire JSP application, and any page in the application can use the Bean."