mdbfailureexample.java

jboss messaging examples, 基于jboss messaging的jms应用例子

/**
 * JBoss, Home of Professional Open Source
 *
 * Distributable under LGPL license.
 * See terms of license at gnu.org.
 */
package org.jboss.example.jms.mdbfailure;

import java.util.HashSet;
import java.util.Set;

import javax.ejb.EJBException;
import javax.ejb.MessageDrivenBean;
import javax.ejb.MessageDrivenContext;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageListener;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.InitialContext;

/**
 * @author <a href="mailto:[e-mail]">Ovidiu Feodorov</a>
 * @version <tt>$Revision: 849 $</tt>

 * $Id: MDBFailureExample.java 849 2006-03-31 17:17:09Z ltexier $
 */
public class MDBFailureExample implements MessageDrivenBean, MessageListener
{

   private MessageDrivenContext ctx;

   private ConnectionFactory cf = null;

   private static Set messageIDs = new HashSet();

   public void onMessage(Message m)
   {
      Session session = null;
      Connection conn = null;

      try
      {

         TextMessage tm = (TextMessage)m;

         String text = tm.getText();

         System.out.println("message " + text + " received");

         System.out.println("message " + (tm.getJMSRedelivered() ? "" : "NOT ")+ "marked as \"redelivered\"");


         // if it is the first time any of the MDB instances from the pool sees the message, the
         // message will cause the MDB instance to "crash"

         synchronized(messageIDs)
         {
            if (!messageIDs.contains(tm.getJMSMessageID()))
            {
               messageIDs.add(m.getJMSMessageID());

               System.out.println("The message has \"broken\" our MDB ...");

               // "crashing" the MDB. The exception won't be caught by our catch clause and it will
               // bubble up

               throw new RuntimeException("Unfortunate events happen ...");

            }
            else
            {
               System.out.println("The message is already \"known\", so let it be processed");
            }
         }

         String result = process(text);
         System.out.println("message processed, result: " + result);

         conn = getConnection();
         session = conn.createSession(false, Session.AUTO_ACKNOWLEDGE);

         Destination replyTo = m.getJMSReplyTo();
         MessageProducer producer = session.createProducer(replyTo);
         TextMessage reply = session.createTextMessage(result);

         producer.send(reply);
         producer.close();

      }
      catch(JMSException e)
      {
         ctx.setRollbackOnly();
         e.printStackTrace();
         System.out.println("The Message Driven Bean failed!");
      }
      finally
      {
         if (conn != null)
         {
            try
            {
                closeConnection(conn);
            }
            catch(Exception e)
            {
                System.out.println("Could not close the connection!" +e);
            }
         }
      }
   }

   private String process(String text)
   {
      // flip the string

      String result = "";

      for(int i = 0; i < text.length(); i++)
      {
         result = text.charAt(i) + result;
      }
      return result;
   }

   public Connection getConnection() throws JMSException
   {

        Connection connection = null;

        try
        {
            connection = cf.createConnection();
            connection.start();

        }
        catch(JMSException e)
        {
           if(connection != null)
           {
               closeConnection(connection);
           }
           System.out.println("Failed to get connection... exception is " + e);
           throw e;
        }

        return connection;
    }

    public void closeConnection(Connection con) throws JMSException
    {

       try
       {
           con.close();

       }
       catch(JMSException jmse)
       {
           System.out.println("Could not close connection " + con +" exception was " +jmse);
           throw jmse;
       }
    }

    public void ejbCreate()
    {
       try
       {
          InitialContext ic = new InitialContext();

          cf = (ConnectionFactory)ic.lookup("java:/JmsXA");

          ic.close();
       }
       catch(Exception e)
       {
          e.printStackTrace();
          throw new EJBException("Failure to get connection factory: " + e.getMessage());
       }
    }

    public void ejbRemove() throws EJBException
    {
       try
       {
          if(cf != null)
          {
              cf = null;
          }
       }
       catch(Exception e)
       {
          throw new EJBException("ejbRemove", e);
       }
    }

    public void setMessageDrivenContext(MessageDrivenContext ctx)
    {
       this.ctx = ctx;
    }


}