Java EE 6 - Part 2 - Writing Stateful Session Beans

Below is an example program using Java EE 6 APIs for Stateful Session beans.

This example shows the client using JNDI lookup directly to access the session bean remote proxy instance. The other way is to use @EJB or using CDI's @Inject

Project: EJB31-Common

import helloworld.vo.GreetingRequest;

import javax.ejb.Remote;

/**

 * Remote interface for stateful session bean.

 *

 * @author rwatsh

 */

@Remote

public interface StatefulHelloWorldBeanRemote {

    GreetingRequest sayHello();

    GreetingRequest[] sayGoodBye();

    

}

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package helloworld.vo;

import java.io.Serializable;

import java.text.SimpleDateFormat;

import java.util.Calendar;

/**

 * Serializable type which holds the session state.

 *

 * @author rwatsh

 */

public class GreetingRequest implements Serializable {

    private Calendar requestTime;

    private String greeting;

    public GreetingRequest(String greet) {

        requestTime = Calendar.getInstance();

        greeting = greet;

    }

    public String toString() {

        SimpleDateFormat df = new SimpleDateFormat();

        String ds = df.format(requestTime.getTime());

        return "helloworld.vo.GreetingRequest [requestTime=" + ds + ", greeting=" + greeting + "]";

    }

}

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Project: EJB31-ejb

package helloworld.beans;

import helloworld.vo.GreetingRequest;

import java.util.ArrayList;

import java.util.List;

import javax.ejb.EJB;

import javax.ejb.Remove;

import javax.ejb.Stateful;

/**

 * This is the stateful session bean implementation. 

 * Requires EJB31-Common.jar in its build path.

 *

 * @author rwatsh

 */

@Stateful

public class StatefulHelloWorldBean implements StatefulHelloWorldBeanRemote {

    private List greetingRequests;

    public StatefulHelloWorldBean() {

        greetingRequests = new ArrayList();

    }

    @Override

    public GreetingRequest sayHello() {

        String greeting = "Hello EJB World";

        GreetingRequest request = new GreetingRequest(greeting);

        greetingRequests.add(request);

        return request;

    }

    @Override

    @Remove

    public GreetingRequest[] sayGoodBye() {

        return greetingRequests.toArray(new GreetingRequest[]{});

    }

}

Project: StandAloneApp

package standaloneapp;

import helloworld.beans.StatefulHelloWorldBeanRemote;

import helloworld.vo.GreetingRequest;

import javax.naming.Context;

import javax.naming.InitialContext;

import javax.naming.NamingException;

/**

 * A standalone Java application client to execute the EJB.

 * Note: it requires the appserver-rt.jar and the EJB31-Common.jar in its build path.

 *

 * @author rwatsh

 */

public class StatefulHelloWorldBeanTest {

    private static StatefulHelloWorldBeanRemote helloWorldBean;

    public static void main(String[] args) {

        System.err.println("standaloneapp.Main.main: Stand-alone App started");

        String jndiPath = "java:global/EJB31/EJB31-ejb/StatefulHelloWorldBean";

        try {

            Context ctx = new InitialContext();

            System.out.println("standaloneapp.Main.main: looking up bean at: "

                    + jndiPath);

            helloWorldBean = (StatefulHelloWorldBeanRemote) ctx.lookup(jndiPath);

            System.out.println("standaloneapp.Main.main: found HelloWorldBean: "

                    + helloWorldBean);

            System.out.println("standaloneapp.Main.main: calling sayHello");

            GreetingRequest greeting = helloWorldBean.sayHello();

            System.out.println("standaloneapp.Main.main: HelloWorldBean said: "

                    + greeting);

            GreetingRequest [] greetings = helloWorldBean.sayGoodBye();

        } catch (NamingException ex) {

            System.err.println(

                    "standaloneapp.Main.main: Could not find HelloWorldBeanRemote");

            System.err.println("standaloneapp.Main.main: JNDI path used for lookup: " + jndiPath);

            ex.printStackTrace();

        }

    }

}