Java Tips By Gaurav: November 2013

Chat Application Using Spring

System Requirements:-

Eclipse Editor or any other.

JDK 1.5 or higher(I am using jdk 1.7.0_03)

Spring jars version 2.5.5.

Other related jars.

Note: - Apache Active MQ Setup is required for the execution of this example. For doing the Active MQ Setup please follow the below link:-

http://www.javatechtipssharedbygaurav.com/2013/10/how-to-work-with-apache-activemq.html

Required Jars:-

activemq-all-5.4.3.jar
xbean-spring-3.7.jar
activemq-pool-5.4.3.jar
commons-pool-1.5.4.jar
spring-tx.jar
spring-beans.jar
spring-context.jar
spring-context-support.jar
spring-core.jar
spring-jms.jar

Note: - I am referring spring framework 2.5.5/dist/modules directory jars.

Steps for creating Eclipse java project for implementing spring JMS:-

Create a java project named ChatApplicationUsingSpring.

Create a package names com.gauarv.springjms.chatapplicationin the src directory.

Create a JMSChatUsingSpring class inside the package named com.gauarv.springjms.chatapplication.

Place the below available code in the JMSChatUsingSpring java file.

JMSChatUsingSpring.java

package com.gauarv.springjms.chatapplication;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import javax.jms.JMSException;

import javax.jms.Message;

import javax.jms.MessageListener;

import javax.jms.Session;

import javax.jms.TextMessage;

import javax.jms.Topic;

import javax.jms.TopicConnection;

import javax.jms.TopicConnectionFactory;

import javax.jms.TopicPublisher;

import javax.jms.TopicSession;

import javax.jms.TopicSubscriber;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import org.springframework.jms.core.JmsTemplate;

public class JMSChatUsingSpring implements MessageListener {

private JmsTemplate messengerJMSTemplate;

private Topic messengerTopic;

private static String userName;

/**

* @return the messengerJMSTemplate

public JmsTemplate getMessengerJMSTemplate() {

return messengerJMSTemplate;

}

/**

* @param messengerJMSTemplate

* the messengerJMSTemplate to set

public void setMessengerJMSTemplate(JmsTemplate messengerJMSTemplate) {

this.messengerJMSTemplate = messengerJMSTemplate;

}

/**

* @param messengerTopic

* the messengerTopic to set

public void setMessengerTopic(Topic messengerTopic) {

this.messengerTopic = messengerTopic;

}

@Override

public void onMessage(Message message) {

/* checking the message of TextMessage type */

if (message instanceof TextMessage) {

try {

String strMessage = ((TextMessage) message).getText();

if (!strMessage.startsWith("[" + userName))

System.out.println(strMessage);

} catch (JMSException jmsException) {

String errMsg = "An Error occurred while extracting message from the destination";

jmsException.printStackTrace();

}

} else {

String errMsg = "Message is not of expected type, as the expected is the TextMessage";

System.err.println(errMsg);

throw new RuntimeException(errMsg);

}

public void subscribe(TopicConnection topicConnection, Topic chatTopic,

JMSChatUsingSpring springJMSChat) throws JMSException {

TopicSession topicSession = topicConnection.createTopicSession(false,

Session.AUTO_ACKNOWLEDGE);

TopicSubscriber ts = topicSession.createSubscriber(chatTopic);

ts.setMessageListener(springJMSChat);

}

public static void main(String arguments[]) throws JMSException, IOException {

if (arguments.length != 1) {

System.out.println("User name is required to join the chat application");

} else {

//If user will enter anything then that will be presumed as his name.

userName = arguments[0];

ApplicationContext applicationContext = new ClassPathXmlApplicationContext(

"spring-chatapplication.xml");

JMSChatUsingSpring springJMSChatApplication = (JMSChatUsingSpring) applicationContext

.getBean("jmsMessenger");

TopicConnectionFactory topicConnectionFactory = (TopicConnectionFactory) springJMSChatApplication.messengerJMSTemplate

.getConnectionFactory();

TopicConnection topicConnection = topicConnectionFactory.createTopicConnection();

springJMSChatApplication.publish(topicConnection, springJMSChatApplication.messengerTopic, userName);

springJMSChatApplication.subscribe(topicConnection, springJMSChatApplication.messengerTopic,

springJMSChatApplication);

}

public void publish(TopicConnection topicConnection, Topic chatTopic, String userId)

throws JMSException, IOException {

TopicSession topicSession = topicConnection.createTopicSession(false,

Session.AUTO_ACKNOWLEDGE);

TopicPublisher topicPublisher = topicSession.createPublisher(chatTopic);

topicConnection.start();

BufferedReader brReader = new BufferedReader(new InputStreamReader(

System.in));

while (true) {

String strMessageToSend = brReader.readLine();

if (strMessageToSend.equalsIgnoreCase("exit")) {

topicConnection.close();

System.exit(0);

}

else {

TextMessage txtMessage = topicSession.createTextMessage();

txtMessage.setText("\n [" + userId + " : " + strMessageToSend + "]");

topicPublisher.publish(txtMessage);

}

Create an XML file and named it as spring-chatapplication.xml in the classpath.

Place the below code in this file

spring-chatapplication.xml

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:jms="http://www.springframework.org/schema/jms" xmlns:amq="http://activemq.apache.org/schema/core"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans.xsd

http://www.springframework.org/schema/context

http://www.springframework.org/schema/context/spring-context.xsd

http://www.springframework.org/schema/jms

http://www.springframework.org/schema/jms/spring-jms.xsd

http://activemq.apache.org/schema/core

http://activemq.apache.org/schema/core/activemq-core.xsd">

<amq:connectionFactory id="mqConnectionFactory"

brokerURL="tcp://localhost:61616" />

<amq:topic id="msgtopic" physicalName="messengertopic" />

<!-- JMSTemplate is a Spring template following the template design pattern

which allows us to communicate with a message broker via JMS. JMSTemplate

takes care of boiler plate code such as exception handling and resource management

even take care of connection pooling. This allows us to concentrate on solving

the 'business' problems, Here, we are suppling the JMS template with the

connection factory(brokerURL) mentioned above -->

</bean>

</bean>

<!-- DefaultMessageListenerContainer is the Spring component equivalent

to the EJB MDB(Message Driven beans). It pools and consumes messages from a JMS

queue. The configuration below is as follows

1. connectionFactory - this is used to connect to the Message Broker which

is Apache Active MQ as per this example.

2. destination - this is the queue which the MessageListener

container is listening on while incoming messages.

3. messageListener - this is the

implementation class which will actually handle the incoming messages. DefaultMessageListener

takes messages from the queue and passes them to the message listener for

processing.

4. concurrentConsumers - this is the number of threads that the DefaultMessageListenerContainer

will handle incoming messages. The default is 1 but in our application

we will have 2 separate threads procsessing incoming messages. Here DefaultMessageListenerContainer

is the example of MDP(Message Driven Pojo). -->

<bean id="poiMessageListenerContainer"

class="org.springframework.jms.listener.DefaultMessageListenerContainer">

</bean>

</beans>

Export the project by selecting and right clicking on the project and then select the option as Export.

In the above window, enlarge the java hierarchy and then select the Runnable JAR file option and then click on Next.

Follow the same steps as the above window, In the Launch configuration we have to pass the main class which will get executed. Then in the Export destination we need to pass the name of the jar and the location, here I am passing the location as the project context and name of the jar as JMSChat.jar. Then in the library handling, select the checkbox as Extract required libraries into the generated JAR.

Open the command prompt by typing “cmd” in the Run.

Start the Apache ActiveMQ server.

Set the java classpath in the system or user variables and then type the command “java -jar JMSChat.jar gaurav” in order to execute the jar. Here this jar is expecting a parameter as name so I am passing gaurav as that parameter.

Again open another cmd and type the same command to execute that jar but pass the different name. Whatever we will type in the another window will reflect into the first window and similarly we can execute this jar in many windows and find that it is working as a chat application.

Results:-

Web Services Hibernate

Java Tips By Gaurav

Monday 25 November 2013

A Spring messaging application

Chat Application Using Spring

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