A question about standard action jsp:useBean

[Joe Allen]

Given:

package foo;
public abstract class Person {
   private String name;

   public void setName(String name) {
      this.name = name;
   }

   public String getName() {
      return name;
   }
}

package foo;
public class Employee extends Person {
   private int empID;

   public void setEmpID(int empID) {
      this.empID = empID;
   }

   public int getEmpID() {
      return empID;
   }
}

Given servlet code like this:

foo.Employee e =   new foo.Employee();
e.setName("Evan");
request.setAttribute("employee",e);

This servlet forwards the request to the following JSP code:

<jsp:useBean id="employee" type="foo.Employee" scope="request">
   <jsp:setProperty name="employee" property="name" value="Fred" />
</jsp:useBean>
Name is: <jsp:getProperty name="employee" property="name" />

My question: would it work, and what is the result?

[Bear Bibeault]

What happened when you tried it?

[Joe Allen]

I have not tried it yet. I have not set up my environments yet. In fact, I changed the original question in HFSJ page 420, trying to confirm that my change would work, as I think it would. Thanks for prompt reply.

[Bear Bibeault]

Is there something that would make you think that it would not work as expected?

[Bear Bibeault]

P.S. I know that you are studying for the exam, but be aware that JSP actions such as getProperty and setProperty are obsolete, replaced by the JSTL and EL as of JSP2 in 2002, so they're not used in modern JSP code anymore (or at least shouldn't be).

[Joe Allen]

Hi Bear,
Thanks very much for the advise. Yes, I am studying for the exam, and I am just right at EL chapter of HFSJ and see how simple EL is.
As for the question above, the original question (HFSJ p420) is :

<jsp:useBean id="person" type="foo.Employee" scope="request">
<jsp:setProperty name="person" property="name" value="Fred" />
</jsp:useBean>
Name is: <jsp:getProperty name="person" property="name" />

What happens if the servlet code looks like:

foo.Person p = new foo.Employee();
p.setName("Evan");
request.setAttribute("person",p);

The book answer is:

FAILS at request time! The "person" attribute is stored at request scope, so the <jsp:useBean> tag won't work since it specifies only a type. The Container KNOWS that if you have only a type specified, there MUST be an existing bean attribute of that name and scope.

I changed "person" to "employee", which is an existing bean attribute. Even if only type(employee) is specified without class, but the Container would find the "employee" class at the request. So I'd think it'd work. Not 100% sure though.