Using Java Bean in JSP to show database record

[Mike Jenkins]

I have links in my Tomcat container that if someone clicks on a specific link it should go to a Record page (Show.jsp) with all the values associated with a record from a database.
For example if someone clicks on a specific link like this:
<a href="Show.jsp?lastname='Jones'">LinkExample</a>
it would take you to a jsp with database info for someone named Jones and show you his info:
Lastname = Jones
Firstname = Mike
City = San Diego

I would like to do this using a Java helper class and bean so I dont have any database connection or Java code in my JSP.

I created Java class file that has Database connection that works with a Java bean. I just dont know how to get the Show.jsp to work with the Java Bean and Java helper class file.

Here is what I have for Show.jsp and this is the part I have been working on the longest but cant get it to work because it doesnt seem to work with the database:

<jsp:useBean id="user" class="num.UserDB"/>
//do I call [B]getUser(lastname)[/B] here and if so how?
<jsp:setProperty name="user" property="*"/>
Last Name: <jsp:getProperty name="user" property="lastname"/><BR>
First Name: <jsp:getProperty name="user" property="firstname"/><BR>
City: <jsp:getProperty name="user" property="city"/><BR>

My Java Helper class that compiles and connects to database:

package num;
import java.io.*;
import java.sql.*;
import java.util.*;
import num.User;
 
 
public class UserDB
{
 
public User getUser(String lastname)
{
User user = new User();
   try
{
Class.forName...//database connection stuff here
        ...........
    ResultSet results = stmt.executeQuery("SELECT * from user where lastname = '" + lastname + "'");
   
if(results.next() == true)
{
results.next();
}
user.setLastname(results.getString("lastname"));
user.setFirstname(results.getString("firstname"));
        user.setFirstname(results.getString("city"));
}
catch(Exception e)
{
System.out.println("Exception...");
}
   return user;
}
 
}

My Java Bean that compiles here:

package num;
 
public class User
{
  private String firstname;
  private String lastname;
private String city;
  
  public User()
  {
     //no arg constructor
  }
  
  public User(String firstname, String lastname, String city)
  {
  this.lastname = lastname;
          this.firstname = firstname;
          this.city = city;
  }
  
  public String getLastname()
  {
     return lastname;
  }
  
  public void setLastname(String lastname)
  {
     this.lastname = lastname;
  }
 
  //more bean methods for all fields here
  
 }
  

[ April 22, 2007: Message edited by: Mike Jenkins ]

[Bear Bibeault]

Before doing anything else, please let us know what container and version of JSP that you are using. The code you posted is doing things using old-fashioned mechanisms and patterns.

[Mike Jenkins]

Originally posted by Bear Bibeault:
Before doing anything else, please let us know what container and version of JSP that you are using. The code you posted is doing things using old-fashioned mechanisms and patterns.

Thanks,

I am using Tomcat 4.1.27 with JDK 1.4 and I dont have JSTL due to restrictions in my environment for downloading software.

[Bear Bibeault]

OK, that explains much.

After my obligatory urging for you to convince the powers-that-be to update to a non-prehistoric version of Tomcat, I'll ask my next question.

Any reason you are sticking to Model 1 vs a Model 2 pattern?

[Mike Jenkins]

I didnt think I needed Model 2 for this process.

Can you give me guidance on the way I am doing it or guidance on adding a Servlet to my attempt for more modern Model 2 way?

Either way I appreciate any suggestions to make this work.

Thanks!

[Bear Bibeault]

I think that model 2 is appropriate for any web app that does any backend processing.

Firstly, you might want to read this article.

What i'd do is to have the original link invoke a servlet. The servlet would delegate the fetching of the user data to a UI-agnostic class in the model (what I think you termed the helper class). The model would return the user information, in the form of a bean-formatted Data Transfer Object (what you are thinking of as the bean) to the servlet. The servlet would tack the bean as a scoped variable onto the request and forward to the JSP.

All of the above is as appropriate for the JSP 1.2 environment as for a more modern setup.

On the JSP is where the main difference lies. In a JSP 2.0 setup, you'd use JSTL and EL. Under JSP 1.2 without JSTL, you'll need to use scriplets and sciptlet expressions.

The <jsp:useBean> action would be used to "hook up" the JSP to the bean that the servlet placed in request scope. The setProperty action you have on your original page is wrong -- it's used to populate a bean from request parameters. Remove it.

You could use the getProperty actions to access the bean, but you could also just use scriptlet expressions.

[Mike Jenkins]

Thanks for your help especially on a Sunday night!

I will now take your guidance and apply it and if any problems I hope I can ask for assistance on here again.

[Bear Bibeault]

But of course!