send message using singlton

SendMessageService.java

package com.e.test.service.first.controller;

import javax.annotation.PostConstruct;
import javax.annotation.PreDestroy;
import javax.annotation.Resource;
import javax.ejb.Lock;
import javax.ejb.LockType;
import javax.ejb.Singleton;
import javax.ejb.Startup;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.JMSException;
import javax.jms.MessageProducer;
import javax.jms.Queue;
import javax.jms.Session;
import javax.jms.TextMessage;

import com.e.test.service.first.api.SendMessage;

@Singleton
@Startup
public class SendMessageService implements SendMessage {
	@Resource(mappedName = "java:/ConnectionFactory")
	private ConnectionFactory connectionFactory;

	@Resource(mappedName = "java:/queue/test")
	private Queue queue;
	private Connection connection;
	private Session session;
	private MessageProducer messageProducer;
	
	@PostConstruct
	public void onStartup() throws JMSException{
		connection = this.connectionFactory.createConnection();
		session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
		messageProducer = session.createProducer(this.queue);
	}
	
	@PreDestroy
	public void onShutdown() throws JMSException{
		messageProducer.close();
		session.close();
		connection.close();		
	}
	
	@Override
	@Lock(LockType.READ)
	public void sendMessage(String text) {
		
		try {
			
			TextMessage message = session.createTextMessage();
			message.setText(text);
			messageProducer.send(message);

			System.out.println("----> W: "+text);
		} catch (Exception e){
			e.printStackTrace();
		}

	}

}