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I am trying to inject an EJB stateless bean in to a servlet, but the servlet throws a NullPointerExcetion. I am using JBOSS to deploy the EJB and servlet.
I am relatively new to the Java world, so I am posting the steps I followed.
Interface
package MavenEJB.Bidding`
import javax.ejb.Local;
@Local
public interface PlaceBid {
public String AddBid();
}
Bean
package MavenEJB.Bidding;
import javax.ejb.Stateless;
@Stateless(name="PlaceBid")
public class PlaceBidBean implements PlaceBid {
public PlaceBidBean(){}
/**
* Include logic to add the bid
*/
public String AddBid(){
return "Placed bid using EJB";
}
}
I created a jar file of the bean using maven and I copied the jar file to "deploy" directory of JBOSS. I am able to see the bean deployed in the JMX console.
Global JNDI Namespace in JMX console
+- PlaceBid (class: org.jnp.interfaces.NamingContext)
| +- local (proxy: $Proxy63 implements interface MavenEJB.Bidding.PlaceBid,interface org.jboss.ejb3.JBossProxy)
My servlet code
public class PlaceBidServlet extends HttpServlet {
@EJB
private PlaceBid placeBid;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<HTML>");
out.println("<HEAD><TITLE>Hello</TITLE></HEAD>");
out.println("<BODY>");
out.println("Output from EJB" +placeBid.AddBid());
//out.println("Output from EJB" );
out.println("</BODY></HTML>");
}
....
}
When I point to the URL of my servlet, I get NullPointerException. When I comment the bean and print something else, it prints fine. So I am sure the problem is with the EJB Dependency Injection in the servlet. I tried many solutions suggested else where, nothing really worked, someone please help me.
559
After a lot of hours I found the problem, I am posting it so someone else can benefit. The problem is, I was using JBOSS 4.2.3 and as this post http://community.jboss.org/message/410211 suggests jboss 4.2.x does not support EJB injection in servlets.
I used Jboss 5.1, also if both the servlet and EJB are not in a single ear package, one must use mappedName to the EJB Injection. I had the servlets in a WAR and the EJB in a separate Jar. Check this post for more details http://community.jboss.org/message/8196#8196
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