EJB Beispiel

Die folgende Verzeichnisstruktur unter irgendeinem logischem Elternteilverzeichnis, wie c:\ejb _example verursachen. Diese Verzeichnisstruktur ist nur zu den Entwicklung Zwecken; die Entwicklungakten werden in eine Glasakte in einem Moment Reißverschluss zugemacht und entfaltet zu den jboss.

The Bean Class

create the bean class as src\server\com\examples\HelloBean.java. This class is a stateless session bean and contains our business logic. In this case it prints out the exciting and always useful "Hello! World".

package com.examples;

import javax.ejb.*;

public class HelloBean implements SessionBean
{
public void ejbCreate() {}
public void ejbActivate() {}
public void ejbPassivate() {}
public void ejbRemove() {}
public void setSessionContext(SessionContext sc){}

public String sayHello ()
{
System.out.println ("Someone called sayHello()");
return “Hello! World”;
}
}

The Remote Interface

Create the remote interface as src\shared\com\examples\Hello.java. This is the interface that remote clients talk to instead of talking directly to the bean class, HelloBean. Notice that its only method is sayHello(), which is the business method in HelloBean.

package com.examples;

import javax.ejb.*;
import java.rmi.*;

public interface Hello extends EJBObject
{
public String sayHello() throws RemoteException;
}

The Home Interface

Create the home interface as src\shared\com\examples\HelloHome.java. This interface will be used to create an instance of the Hello interface when we want to execute the sayHello() business logic.

package com.examples;

import javax.ejb.*;
import java.rmi.*;

public interface Hello extends EJBObject
{
public String sayHello() throws RemoteException;
}

The Client

create the client as src\client\com\examples\HelloClient.java. This is the "remote" client that will use our session bean. First, it uses the InitialContext to get a handle to HelloHome. It then uses the HelloHome interface to create hello. hello is a remote interface representing our bean class. After hello is used to execute the business logic (sayHello), the bean is released via the remove method.

package com.examples;

import javax.ejb.*;
import java.rmi.*;
import javax.rmi.*;
import javax.naming.*;

public class HelloClient
{
public static void main (String[] args) throws Exception
{
Context c = new InitialContext();
Object o = c.lookup ("Hello");

HelloHome home =
(HelloHome)PortableRemoteObject.narrow (o,HelloHome.class);
Hello hello = home.create();
System.out.println (hello.sayHello());
hello.remove();
}
}

ejb-jar.xml

Create the ejb-jar.xml file in target\server\META-INF. This deployment descriptor contains information that the jboss EJB container needs in order to deploy and run our EJB.

<!DOCTYPE ejb-jar PUBLIC "-//Sun Microsystems, Inc.//DTD Enterprise
JavaBeans 2.0//EN" "http://java.sun.com/dtd/ejb-jar_2_0.dtd">
<ejb-jar>
<enterprise-beans>
<session>
<ejb-name>Hello</ejb-name>
<home>com.examples.HelloHome</home>
<remote>com.examples.Hello</remote>
<ejb-class>com.examples.HelloBean</ejb-class>
<session-type>Stateless</session-type>
<transaction-type>Container</transaction-type>
</session>
</enterprise-beans>
</ejb-jar>

jndi.properties

Create the jndi.properties file in target\client. This file defines properties that are required in order to use JNDI to find EJBs on the network.

java.naming.factory.initial=org.jnp.interfaces.NamingContextFactory
java.naming.provider.url=jnp://localhost:1099

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