EJB dependency injection into Servelt - WAS7_问答_开发者

EJB dependency injection into Servelt - WAS7

开发者 https://www.devze.com 2023-04-01 16:17 出处：网络

I am trying to inject an EJB with the @EJB annotation : when I inject an EJB into another EJB it works fine.

I am trying to inject an EJB with the @EJB annotation :

when I inject an EJB into another EJB it works fine.
when I inject the same EJB into a servlet I got a null pointer exception (my EJB is null).

myapp.ear contains the following :

myapp.war (where the servlet is located)
myapp.jar (where the EJBs are)

EJB Interface :

package com.mycompany.myapp.ejb.hello;

@Local
public interface HelloEjb {
    public final static String NAME = "HelloEjb";   
    public String sayHello();
}

EJB Impl :

package com.mycompany.myapp.ejb.hello;

@Stateless(name = HelloEjb.NAME)
public class HelloEjbImpl implements HelloEjb {

    @Override
    public String sayHello() {
        return "Hello";
    }
}

My Servlet :

public class HelloServlet extends HttpServlet {

    @EJB
    private HelloEjb helloEjb;

    @Override
    protected 开发者_开发问答void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.setContentType("text/html");
        PrintWriter out = resp.getWriter();
        out.println("<html>");
        out.println("This is my stateless session-EJB: " + helloEjb.sayHello());
        out.println("</html>");
        out.close();
    }
}

The web.xml in the WAR has nothing spetacular, only the servlet defintion, no ejb tags :

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="MyApp" version="2.5"
    xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">

    <!-- General -->
    <display-name>My App</display-name>

    <!-- Standard Action Servlet Configuration -->
    <servlet>
        <servlet-name>helloServlet</servlet-name>
        <servlet-class>com.mycompany.myapp.web.servlet.HelloServlet</servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <!-- Standard Action Servlet Mapping -->
    <servlet-mapping>
        <servlet-name>helloServlet</servlet-name>
        <url-pattern>*.do</url-pattern>
    </servlet-mapping>

    <!-- The Usual Welcome File List -->
    <welcome-file-list>
        <welcome-file>/index.jsp</welcome-file>
    </welcome-file-list>

</web-app>

If in the servlet I use lookup, it works I am able to get the EJB :

helloEjb = ctx.lookup("ejblocal:com.mycompany.myapp.ejb.hello.HelloEjb");

I am using Websphere 7 & EJB 3.0

Any help would be much appreciated.

My first shot is, if you specifiy a 'name' for your stateless EJB you should inject it with 'mappedName' attribute eg. '@EJB(mappedName="foo.FooRemote")'

Which Fixpack are you on? Prior to FixPack 11, the dependency injection mechanism of WAS7 was shot to hell. Try upgrading to 15 (don't use the latest, 17, nasty bug working with commons-logging)