Re: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Fri, 25 May 2001 06:33:29 -0700

Title: Re: problems installing tomcat on linux
Darn it all!
 
The jsp should look like this.  I forgot to take my own class name out of a few lines.
 
<%try{
       System.out.println((request.getAttribute("thebean") == null));
       System.out.println((request.getAttribute("thebean") instanceof com.blah.blah.AnyCustomBean));
       System.out.println((request.getAttribute("thebean").getClass().getName()));
       System.out.println((com.blah.blah.AnyCustomBean)request.getAttribute("thebean"));
  }catch (ClassCastException e){
       System.out.println("CLASS CAST EXCEPTION!");
  }
%>
----- Original Message -----
Sent: Friday, May 25, 2001 9:53 AM
Subject: Re: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Mahesh,
 
One more thing, in the servlet the line...
 
    thebean = (com.blah.blah.AnyCustomBean) Beans.instantiate(this.getClass().getClassLoader(), "com.blah.blah.AnyCustomBean");
 
...needs to have a try/catch block around it for a ClassNotFoundException.
 
Leon
----- Original Message -----
Sent: Friday, May 25, 2001 9:48 AM
Subject: Re: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Here is a very scaled down version of the dispatch servlet. Switch the name of the bean ('com.blah.blah.AnyCustomBean') in the jsp and servlet to any custom bean you wish to try out.
 
Create a .jsp page for the servlet to forward the request to that looks something like this:
 
<%@ page session="false" errorPage="error.jsp" %>
<%@ page import = "com.blah.blah.AnyCustomBean" %>
 
<%try{
       System.out.println((request.getAttribute("thebean") == null));
       System.out.println((request.getAttribute("thebean") instanceof zedak.docworx.jspsupport.beans.BrandBean));
       System.out.println((request.getAttribute("thebean").getClass().getName()));
       System.out.println((zedak.docworx.jspsupport.beans.BrandBean)request.getAttribute("thebean"));
  }catch (ClassCastException e){
       System.out.println("CLASS CAST EXCEPTION!");
  }
%>
 
<jsp:useBean id="thebean" scope="request" class="com.blah.blah.AnyCustomBean" />
 
Change the name of the jsp file in the servlet to match the .jsp file name you created above.
 
Thanks!
 
Leon
----- Original Message -----
Sent: Friday, May 25, 2001 9:20 AM
Subject: RE: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Can you send the example code ?
 
 
-----Original Message-----
From: Leon Palermo [mailto:[EMAIL PROTECTED]]
Sent: Friday, May 25, 2001 2:21 PM
To: [EMAIL PROTECTED]
Subject: Re: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Yes, but I need to cast it to use the Bean specific functionality and...
 
    (com.blah.blah.MyBean)request.getAttribute("thename");
 
...causes the ClassCastException to occur.
 
----- Original Message -----
Sent: Friday, May 25, 2001 9:11 AM
Subject: RE: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Hi
 
Have you tried the simple way of :
 
com.blah.blah.MyBean abean = new com.blah.blah.MyBean();
request.setAttribute("thename", abean);
 
in JSP :

com.blah.blah.MyBean abean = request.getAttribute("thename");
 
regards
mahesh
 
 
-----Original Message-----
From: Leon Palermo [mailto:[EMAIL PROTECTED]]
Sent: Friday, May 25, 2001 2:02 PM
To: [EMAIL PROTECTED]
Subject: (EXPERTS ONLY) Bean Creation in Dispatch Servlet

Hello All,
 
Let me preface this email by saying that I only put 'EXPERTS ONLY' so you hot shot programmers would actually read this email.  If you are reading this, it worked!
 
I have an odd problem that I was hoping someone could help with.
 
I have a servlet that all jsps in the system are dispatched from.  I create a bean in this servlet and add it to the request object like so...
 
    com.blah.blah.MyBean abean = (com.blah.blah.MyBean) Beans.instantiate(this.getClass().getClassLoader(),"com.blah.blah.MyBean");
    ...
    request.setAttribute("thename", abean);
               
I have also tried this to create the bean....
 
    com.blah.blah.MyBean abean = new com.blah.blah.MyBean();
 
and also tried to place the object in the request like so....
 
    pageContext.setAttribute("thename", abean, PageContext.REQUEST_SCOPE);
 
Anywho, I then have the following in my jsp page...
 
    <jsp:useBean id="thename" scope="request" class="com.blah.blah.MyBean" />
 
I get a java.lang.ClassCastException from the jsp.  So, I decided to do a little error hunting in a jsp using the following code...
 
<%try{
    System.out.println(request.getAttribute("thename") == null);
    System.out.println(request.getAttribute("thename") instanceof com.blah.blah.MyBean);
    System.out.println(request.getAttribute("thename").getClass().getName());
    System.out.println(zedak.docworx.jspsupport.beans.BrandBean)request.getAttribute("thename"));
}catch (ClassCastException e){
    System.out.println("CLASS CAST EXCEPTION!");
}
%>
 
The results of the code is as follows:
 
    false
    false
    com.blah.blah.MyBean
    CLASS CAST EXCEPTION!
 
So, the attribute is present in the request object, it is not an instance of 'com.blah.blah.MyBean'; but the object's class name is 'com.blah.blah.MyBean'.  Does anyone have an idea what is going on?  How can the object's class name be 'com.blah.blah.MyBean' but not be able to cast to 'com.blah.blah.MyBean'?
 
Thanks in advance!
 
Leon Palermo


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