Simple Bean Examples

[bossfn]

hi guys,

I'm just starting to get into all the j2ee stuff. Recently I've gone over a couple examples with EJBs. I'm wondering if any of you have any more simple EJBs that I could check out. (probably the first ones you wrote!)

I learn by example very well, and most of the EJB samples I've found are little much to start with. Anything you can hook me up with would be great! Send it however you like.

[kandati]

the one that i am posting is an example of Message driven bean. needs JMS......
i used weblogic8.1
let me post the web.xml, weblogic-ejb-jar.xml,EmailMDB.java and EmailClient.java
hope that helps

web.xml.....
<!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>
<message-driven>
<ejb-name>EmailMDB</ejb-name>
<ejb-class>EmailMDB</ejb-class>
<transaction-type>Container</transaction-type>
<acknowledge-mode>Auto-acknowledge</acknowledge-mode>
<message-driven-destination>
<destination-type>javax.jms.Queue</destination-type>
<subscription-durability>Durable</subscription-durability>
</message-driven-destination>
</message-driven>
</enterprise-beans>
</ejb-jar>

weblogic-ejb-jar.xml

<?xml version="1.0"?>

<!DOCTYPE weblogic-ejb-jar PUBLIC "-//BEA Systems, Inc.//DTD WebLogic 7.0.0 EJB//EN" "http://www.bea.com/servers/wls700/dtd/weblogic-ejb-jar.dtd" >

<weblogic-ejb-jar>
<weblogic-enterprise-bean>
<ejb-name>EmailMDB</ejb-name>
<message-driven-descriptor>
<pool>
<max-beans-in-free-pool>200</max-beans-in-free-pool>
<initial-beans-in-free-pool>5</initial-beans-in-free-pool>
</pool>
<destination-jndi-name>myqueue</destination-jndi-name>
</message-driven-descriptor>
<jndi-name>jms/EmailMDB</jndi-name>
</weblogic-enterprise-bean>
</weblogic-ejb-jar>



EmailMDB.java


import java.util.*;
import javax.ejb.*;
import javax.jms.*;


public class EmailMDB implements MessageDrivenBean, MessageListener {

private MessageDrivenContext context;

// --------------------------------------------------------------
// EJB Methods from MessageDrivenBean interface
// --------------------------------------------------------------
public void ejbCreate() {
System.out.println("EmailMDB: ejbCreate called");
}

public void ejbRemove() {
System.out.println("EmailMDB: ejbRemove called");
}

public void setMessageDrivenContext(MessageDrivenContext context) {
System.out.println("setMessageDrivenContext called");
this.context = context;
}


public void onMessage(Message message) {
System.out.println("EmailMDB: onMessage called");
TextMessage mapmessage = (TextMessage) message;
try {

// Go through the map message and create a map for sendmail(Map)
System.out.println("Sending email: EmailHelper.sendmail(mail)" + mapmessage.getText());

} catch(Exception e) {
e.printStackTrace();
}
}
}



EmailClient.java

import java.rmi.*;
import java.util.*;

import javax.jms.*;
import javax.naming.*;

/**
* EmailClient is responsible for sending an email mapmessage to the queue
*/
public class EmailClient {
private static String QUEUE_NAME = "myqueue";
private static String CONNECTION_FACTORY = "javax.jms.QueueConnectionFactory";
private static String PROVIDER_URL = "t3://localhost:7001";

private QueueSender sender;
private QueueSession session;

/**
* Constructor: Setup JMS for publishing
*/
public EmailClient() {
try {
Context ctx = getInitialContext();

// Lookup a JMS connection factory
QueueConnectionFactory conFactory =
(QueueConnectionFactory) ctx.lookup(CONNECTION_FACTORY);
// Create a JMS connection
QueueConnection connection = conFactory.createQueueConnection();

// Create a JMS session object
session = connection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE);

// Lookup a JMS queue
Queue chatQueue = (Queue) ctx.lookup(QUEUE_NAME);

// Create a JMS sender
sender = session.createSender(chatQueue);
} catch(Exception e) {
e.printStackTrace();
}
}


/**
* Method: sendmail(Map mail)
*/
public void sendmail() throws Exception {
TextMessage message = session.createTextMessage();

message.setText("this is working");
// send the mapmessage to the Queue
sender.send(message);
}


/**
* Method: getInitialContext()
*
* Login to JNDI
*
* @return Context The initial context
*/
private Context getInitialContext() throws NamingException {
Properties env = new Properties();
env.put("java.naming.factory.initial", "weblogic.jndi.WLInitialContextFactory");
env.put("java.naming.provider.url", PROVIDER_URL);

return new InitialContext(env);
}


/**
* Static Method: java com.customware.client.EmailClient to_addr [from_addr] [subject] [body]
*/
public static void main(String args[]) throws Exception {

System.out.println("\nBeginning EmailClient\n");
EmailClient client = new EmailClient();

System.out.println("Sending mail message");
client.sendmail();
}
}



all the best