VÍ DỤ VỀ MESSAGE-DRIVEN BEANS ĐƠN GIẢN

VÍ DỤ VỀ MESSAGE-DRIVEN BEANS ĐƠN GIẢN

Create by: Võ văn Hải

Email: vovanhaiQN.google.com

Home page: https://vovanhai.wordpress.com

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Thiết kế 1 ví dụ ứng dụng:

1.    Tạo thư mục MDB_Simple_EX

2.    Tạo thư mục server.

3.    Tạo file MessageBean.java trong thư mục server có nội dung sau

import javax.ejb.*; import javax.naming.*; import javax.jms.*; /** * The MessageBean class is a message-driven bean.  It implements * the javax.ejb.MessageDrivenBean and javax.jms.MessageListener * interfaces. It is defined as public (but not final or * abstract).  It defines a constructor and the methods * setMessageDrivenContext, ejbCreate, onMessage, and * ejbRemove. */ public class MessageBean implements MessageDrivenBean, MessageListener { private transient MessageDrivenContext mdc = null; private Context context; /** * Constructor, which is public and takes no arguments. */ public MessageBean() { System.out.println(“In MessageBean.MessageBean()”); } /** * setMessageDrivenContext method, declared as public (but * not final or static), with a return type of void, and * with one argument of type javax.ejb.MessageDrivenContext. * * @param mdc    the context to set */ public void setMessageDrivenContext(MessageDrivenContext mdc) { System.out.println(“In ” + “MessageBean.setMessageDrivenContext()”); this.mdc = mdc; } /** * ejbCreate method, declared as public (but not final or * static), with a return type of void, and with no * arguments. */ public void ejbCreate() { System.out.println(“In MessageBean.ejbCreate()”); } /** * onMessage method, declared as public (but not final or * static), with a return type of void, and with one argument * of type javax.jms.Message. * * Casts the incoming Message to a TextMessage and displays * the text. * * @param inMessage    the incoming message */ public void onMessage(Message inMessage) { TextMessage msg = null; try { if (inMessage instanceof TextMessage) { msg = (TextMessage) inMessage; System.out.println(“MESSAGE BEAN: Message ” + “received: ” + msg.getText()); } else { System.out.println(“Message of wrong type: ” + inMessage.getClass().getName()); } } catch (JMSException e) { System.err.println(“MessageBean.onMessage: ” + “JMSException: ” + e.toString()); mdc.setRollbackOnly(); } catch (Throwable te) { System.err.println(“MessageBean.onMessage: ” + “Exception: ” + te.toString()); } } /** * ejbRemove method, declared as public (but not final or * static), with a return type of void, and with no * arguments. */ public void ejbRemove() { System.out.println(“In MessageBean.remove()”); } }

4.    Tạo thư mục META-INF

5.    Tạo tập tin ejb-jar.xml trong thư mục META-INF có nội dung sau

<!DOCTYPE ejb-jar PUBLIC “-//Sun Microsystems, Inc.//DTD Enterprise JavaBeans 2.0//EN” “http://java.sun.com/dtd/ejb-jar_2_0.dtd”&gt; <ejb-jar> <enterprise-beans> <message-driven> <ejb-name>TestMDB</ejb-name> <ejb-class>MessageBean</ejb-class> <transaction-type>Container</transaction-type> <message-driven-destination> <destination-type>javax.jms.Queue</destination-type> <subscription-durability>NonDurable</subscription-durability> </message-driven-destination> </message-driven> </enterprise-beans> </ejb-jar>

6.    Tạo tập tin jboss.xml trong thư mục META-INF có nội dung sau

<?xml version=”1.0″ encoding=”UTF-8″?> <jboss> <enterprise-beans> <message-driven> <ejb-name>TestMDB</ejb-name> <destination-jndi-name>queue/TestMDB</destination-jndi-name> </message-driven> </enterprise-beans> </jboss>

7.    Tạo file compile.bat có nội dung sau

javac -d . *.java pause

Chạy file này để biên dịch.

8.    Tạo tập tin createJAR.bat có nội dung sau

jar cvf TestMDB.jar *.class META-INF/*.xml pause

Chạy file này ta sẽ có tập tin TestMDB.jar.

9.    Triển khai ứng dụng bằng cách copy vào thư mục %JBOSS_HOME%\server\default\deploy, ta được kết quả như sau nếu thành công

… 19:51:41,620 INFO  [EjbModule] Deploying TestMDB 19:51:41,729 WARN  [JMSContainerInvoker] Could not find the queue destination-jn di-name=queue/TestMDB 19:51:41,729 WARN  [JMSContainerInvoker] destination not found: queue/TestMDB reason: javax.naming.NameNotFoundException: TestMDB not bound 19:51:41,729 WARN  [JMSContainerInvoker] creating a new temporary destination: q ueue/TestMDB 19:51:41,745 INFO  [TestMDB] Bound to JNDI name: queue/TestMDB 19:51:41,776 INFO  [EJBDeployer] Deployed: file:/C:/javaSoft/jboss-4.2.2.GA/serv er/default/deploy/TestMDB.jar …

10.  Tạo thư mục client

11.  Tạo file SimpleClient.java trong thư mục client với nội dung sau

import javax.jms.*; import javax.naming.*; /** * The SimpleClient class sends several messages to a queue. */ public class SimpleClient { /** * Main method. */ public static void main(String[] args) { System.setProperty(“java.naming.factory.initial”,”org.jnp.interfaces.NamingContextFactory”); System.setProperty(“java.naming.provider.url”,”localhost:1099″); Context                 jndiContext = null; QueueConnectionFactory  queueConnectionFactory = null; QueueConnection         queueConnection = null; QueueSession            queueSession = null; Queue                   queue = null; QueueSender             queueSender = null; TextMessage             message = null; final int               NUM_MSGS = 10; /* * Create a JNDI API InitialContext object. */ try { jndiContext = new InitialContext(); } catch (NamingException e) { System.out.println(“Could not create JNDI API ” + “context: ” + e.toString()); System.exit(1); } /* * Look up connection factory and queue.  If either does * not exist, exit. */ try { queueConnectionFactory = (QueueConnectionFactory) jndiContext.lookup(“ConnectionFactory”); queue = (Queue) jndiContext.lookup(“queue/TestMDB”); } catch (NamingException e) { System.out.println(“JNDI API lookup failed: ” + e.toString()); System.exit(1); } /* * Create connection. * Create session from connection; false means session is * not transacted. * Create sender and text message. * Send messages, varying text slightly. * Finally, close connection. */ try { queueConnection = queueConnectionFactory.createQueueConnection(); queueSession = queueConnection.createQueueSession(false, Session.AUTO_ACKNOWLEDGE); queueSender = queueSession.createSender(queue); message = queueSession.createTextMessage(); for (int i = 0; i < NUM_MSGS; i++) { message.setText(“This is message ” + (i + 1)); System.out.println(“Sending message: ” + message.getText()); queueSender.send(message); } } catch (JMSException e) { System.out.println(“Exception occurred: ” + e.toString()); } finally { if (queueConnection != null) { try { queueConnection.close(); } catch (JMSException e) {} } System.exit(0); } } }

12.  Tạo file compile.bat với nội dung sau

javac -d . *.java pause

Chạy file này để biên dịch

13.  Tạo file run.bat với nội dung sau

java Client pause

14.  Thực thi file run.bat, kết quả dạng như sau:

D:\Bai giang Aptech\Aptech – Semester 4\JMS\exmples\Message-Driven Beans\mdb_JMS \client>java SimpleClient Sending message: This is message 1 Sending message: This is message 2 Sending message: This is message 3 D:\Bai giang Aptech\Aptech – Semester 4\JMS\exmples\Message-Driven Beans\mdb_JMS \client>pause Press any key to continue . . .

Lúc đó trên cửa sổ JBOSS ta nhận được kết quả sau

19:56:56,693 INFO  [STDOUT] In MessageBean.MessageBean() 19:56:56,693 INFO  [STDOUT] In MessageBean.setMessageDrivenContext() 19:56:56,693 INFO  [STDOUT] In MessageBean.ejbCreate() 19:56:56,693 INFO  [STDOUT] MESSAGE BEAN: Message received: This is message 1 19:56:56,724 INFO  [STDOUT] MESSAGE BEAN: Message received: This is message 2 19:56:56,724 INFO  [STDOUT] MESSAGE BEAN: Message received: This is message 3

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