Add init parameter to listerner from web.xml

[Fouad Fares]

Hello,
I have a web application developped under 9i jdeveloper .
1- I'm using the web.xml file as a configuration file .
2- I have a java listener of servletcontext and sessions .
I'm not able to read parameter initialised in my web.xml
from this listener class.
Here are the web.xml :
=================================
<web-app>
<session-config>
<session-timeout>30</session-timeout>
</session-config>
<listener>
<listener-class>Banque.divers.Jcls_Init</listener-class>
<init-param>
<param-name>path</param-name>
<param-value>bnq</param-value>
</init-param>
</listener>
<mime-mapping>
Etc ...
</web-app>
=================================
Here are the Listener Class :
=================================
package Banque.Divers;
import javax.servlet.http.*;
Etc ...
public class Jcls_Init implements ServletcontextListener, HttpSessionListener
{
public Jcls_init()
{
}
ServletContext servletcontext ;
public void contextInitialialized(ServletContextEvent sce)
{
String tag = sce.getServletContext().getInitParameter("tag") ;
System.out.println(tag);
}
It returns me a null value .
=================================
Could you please advise me how can i solve this problem ?
Thank You in advance,
Fouad fares.

[Baka Neko]

public void contextInitialialized(ServletContextEvent sce)
{
String tag = sce.getServletContext().getInitParameter("Name of the Parameter you wannna have the value, in your case path");
System.out.println(tag);
}
Im also in the middle of this problem. Lol
Maybe this will help ya...for me Im still getting NULL ...maybe there is something wrong with the invoker of the web.xml in Tomcat-Folder..o_O?
Any help would be great!
Baka out

[Fouad Fares]

Hello,
Sorry i mean getInitParameter("path") and not tag .
it's typing error .
Best regards .

[Mike Curwen]

From the spec:

<!--
The init-param element contains a name/value pair as an
initialization param of the servlet
 
Used in: filter, servlet
-->
<!ELEMENT init-param (param-name, param-value, description?)>

You cannot use an init-param just anywhere. It should also be noted that this value is retrievable from the ServletConfig and FilterConfig objects, which are passed in to the init methods of servlets and filters, respectively.

You might try using a context-param element:

<!--
The context-param element contains the declaration of a web
application�s servlet context initialization parameters.
 
Used in: web-app
-->

Those parameters serve to initialize anything and everything that can obtain a ServletContext object. (servlets, filters, listeners, etc).
[ December 10, 2003: Message edited by: Mike Curwen ]

[Chad Dalton]

Basically,
replace

String tag = sce.getServletContext().getInitParameter("tag");

with

String tag = getInitParameter("path");

--chad

[Mike Curwen]

Basically, that's wrong.

The code should remain the same, it's *where* in web.xml you declare the parameter, and with what tag.
[ December 12, 2003: Message edited by: Mike Curwen ]

[Chad Dalton]

Originally posted by Mike Curwen:
Basically, that's wrong.

The code should remain the same, it's *where* in web.xml you declare the parameter, and with what tag.
[ December 12, 2003: Message edited by: Mike Curwen ]

Excuse me, he wants the parmeter to be servlet level and NOT context level from what I understand. Now if he wants the parmeter to be context level (and available to all servlets in that context) then he leaves the code alone and fixes the web.xml, but if he wants ONLY his listener class to use the parmeter then he needs to change the code to what I provided.
--chad

[Chad McGowan]

Originally posted by Chad Dalton:

Excuse me, he wants the parmeter to be servlet level and NOT context level from what I understand. Now if he wants the parmeter to be context level (and available to all servlets in that context) then he leaves the code alone and fixes the web.xml, but if he wants ONLY his listener class to use the parmeter then he needs to change the code to what I provided.
--chad

That is incorrect. Neither of these will work with his current web.xml file. The way the parameter has been defined in his code snippet is wrong, no matter what code you try to use to get the value back out. If he wants to define the parameter at a servlet level, then it should go in the init params for the servlet, otherwise he can define it as a context-param element.
Either way, he is going to have to change how it is currently defined in the web.xml

[Mike Curwen]

Excuse me, he wants the parmeter to be servlet level and NOT context level from what I understand.

It's not a question of what he wants, it's what will work or not. If you want to use web.xml to configure a Listener (not a servlet), then you *need* to use a context-param, you have no other choice. The DTD tells you that you cannot place an init-param inside a listener declaration. In fact, I'm quite surprised Tomcat doesn't have a big problem with it. I believe it should at least throw a warning.

change the code to what I provided

The code you provided does not work in a Listener, only classes that extend HttpServlet, and only those that call super.init(config); in their init() method (if they're overriding it).

web.xml:
 
 
<web-app>
 
<context-param>
<param-name>per_context_foo</param-name>
<param-value>per_context_bar</param-value>
</context-param>
 
<listener>
<listener-class>ca.barecode.wishlist.MyListener</listener-class>
<init-param>
<param-name>bad</param-name>
<param-value>impossible</param-value>
</init-param>
</listener>
 
 
<servlet>
<servlet-class>ca.barecode.wishlist.MyServlet</servlet-class>
<servlet-name>placebo</servlet-name>
<load-on-startup>1</load-on-startup>
<init-param>
<param-name>per_servlet_foo</param-name>
<param-value>per_servlet_bar</param-value>
</init-param>
</servlet>
 
</web-app>
 
 
MyListener.java:
 
package ca.barecode.wishlist;
import javax.servlet.*;
import javax.servlet.http.*;
public class MyListener implements ServletContextListener {
 
 
ServletContext cntx ;
 
public void contextInitialized(ServletContextEvent sce) {
cntx = sce.getServletContext();
 
String foo = cntx.getInitParameter("per_context_foo");
System.out.println("MyListener: per_context_foo from context " + foo);
 
//foo = getInitParameter("bad");
// compiler error!
 
String bad = cntx.getInitParameter("bad");
System.out.println("MyListener: bad " + bad);
 
 
}
 
public void contextDestroyed(ServletContextEvent sce) {}
 
}
 
 
MyServlet.java:
  
package ca.barecode.wishlist;
 
 
import javax.servlet.*;
import javax.servlet.http.*;
 
public class MyServlet extends HttpServlet {
 
public void init(ServletConfig config) throws ServletException {
super.init(config);
 
String foo = config.getInitParameter("per_servlet_foo");
System.out.println("MyServlet: per_servlet_foo: " + foo);
// OR
foo = getInitParameter("per_servlet_foo");
System.out.println("MyServlet: per_servlet_foo from superclass method: "+ foo);
 
 
String foo2 = config.getServletContext().getInitParameter("per_context_foo");
System.out.println("MyServlet: per_context_foo from context: "+ foo2);
 
 
}
}
 
 
 
output on console:
 
MyListener: per_context_foo from context per_context_bar
MyListener: bad null
MyServlet:  per_servlet_foo: per_servlet_bar
MyServlet:  per_servlet_foo from superclass method: per_servlet_bar
MyServlet:  per_context_foo from context: per_context_bar

[ December 15, 2003: Message edited by: Mike Curwen ]