JavaEE5学习札记03-JMS介绍与使用-5

JavaEE5学习笔记03-JMS介绍与使用---5

? JMS的事务控制

JMS控制消息发送的事务有2种途径，一个是利用Connection接口建立事务性会话，另一个就是利用JTA标准接口控制事务了。

Session事务性会话

??? public void sendMessage() {

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?????? try {

?????????? String Connection_Factory = "ConnectionFactory";

?

?????????? Context context = getInitialContext();

?

?????????? ConnectionFactory connectionFactory = (ConnectionFactory) context

????????????????? .lookup(Connection_Factory);

?

?????????? Destination dest = (Destination) context.lookup("jbossJMSTopic");

?

?????????? Connection connection = connectionFactory.createConnection();

?

?????????? Session session = connection.createSession(true,

????????????????? Session.CLIENT_ACKNOWLEDGE);

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?????????? MessageProducer sender = session.createProducer(dest);

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?????????? sender.setDeliveryMode(DeliveryMode.PERSISTENT);

?????????? // sender.setTimeToLive(2000);

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?????????? sender.setPriority(9);

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?????????? TextMessage textMessage = session.createTextMessage();

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?????????? textMessage.setStringProperty("ConType", "txt");

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?????????? textMessage.setText("hello 速速");

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?????????? sender.send(textMessage);

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?????????? System.out.println("停顿5秒钟");

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?????????? // 等待50秒

?????????? Thread.sleep(5000);

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?????????? System.out.println("停顿5秒钟完毕");

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?????????? textMessage.setText("welcome to JMS");

?

?????????? sender.send(textMessage);

??????????

?????????? //此处抛出运行时异常

?????????? int a = 1/0;

??????????

?????????? session.commit();

?????????? session.close();

?????????? connection.close();

?????? } catch (Exception e) {

?????????? e.printStackTrace();

?????? }

?

??? }

此代码会抛出异常

java.lang.ArithmeticException: / by zero

所以消费者是无法接收到此消息的，因为事务还没有提交呢，就抛出了异常，还有一点就是在建立session的时候如果是建立的事务性会话，必须手工代码让会话提交事务session.commit();消息才能送达到目的地！

JTA管理JMS消息事务

如果需要让JMS、数据库、EJB操作等参与到事务当中，则应该考虑JTA事务。因为Session事务性会话总会打开一个新的事务，在Session中未commit之前，全部都在一个Session事务中，而数据库操作、EJB操作等等不能参与、共享此会话性事务中。所以此时应该用JTA来包装此事务。

来看JTA控制的消息生产者的一个Servlet代码

public void doPost(HttpServletRequest request, HttpServletResponse response)

?????????? throws ServletException, IOException {

?

?????? UserTransaction userTransaction = null;

?????? java.sql.Connection connectionSQL = null;

?????? DataSource dataSource = null;

?

?????? Statement statement = null;

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?????? Context context;

?????? try {

?????????? context = new InitialContext();

??????????

?????????? dataSource = (DataSource) context.lookup("java:/jbossdemo");

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?????????? String Connection_Factory = "ConnectionFactory";

?

?????????? ConnectionFactory connectionFactory = (ConnectionFactory) context

????????????????? .lookup(Connection_Factory);

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?????????? Destination dest = (Destination) context.lookup("jbossJMSTopic");

?

?????????? // 获得JTA相关用户接口

?????????? userTransaction = (UserTransaction) context

????????????????? .lookup("UserTransaction");

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?????????? // 开始事务

?????????? userTransaction.begin();

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?????????? javax.jms.Connection connection = connectionFactory.createConnection();

?

?????????? Session session = connection.createSession(false,

????????????????? Session.AUTO_ACKNOWLEDGE);

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?????????? MessageProducer sender = session.createProducer(dest);

?

?????????? sender.setDeliveryMode(DeliveryMode.PERSISTENT);

?????????? // sender.setTimeToLive(2000);

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?????????? sender.setPriority(9);

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?????????? TextMessage textMessage = session.createTextMessage();

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?????????? textMessage.setStringProperty("ConType", "txt");

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?????????? textMessage.setText("hello 第一个消息");

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?????????? sender.send(textMessage);

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?????????? System.out.println("停顿5秒钟");

?

?????????? // 等待50秒

?????????? Thread.sleep(5000);

?

?????????? System.out.println("停顿5秒钟完毕");

?

?????????? textMessage.setText("welcome to JMS");

?

?????????? sender.send(textMessage);

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?????????? // 执行插入数据业务

?????????? connectionSQL = dataSource.getConnection();

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?????????? statement = connectionSQL.createStatement();

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?????????? String insert1 = "insert into person values(13,'欧阳上智')";

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?????????? String insert2 = "insert into person values(14,'欧阳尚智')";

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?????????? statement.executeUpdate(insert1);

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?????????? statement.executeUpdate(insert2);

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?????????? int a = 1 / 0;

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?????????? // 提交JTA事务

?????????? userTransaction.commit();

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?????????? session.close();

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?????????? connection.close();

?????? } catch (Exception e) {

?????????? // TODO Auto-generated catch block

?????????? e.printStackTrace();

?????????? try {

????????????? userTransaction.rollback();

?????????? } catch (IllegalStateException e1) {

?????? ?????? // TODO Auto-generated catch block

????????????? e1.printStackTrace();

?????????? } catch (SecurityException e1) {

????????????? // TODO Auto-generated catch block

????????????? e1.printStackTrace();

?????????? } catch (SystemException e1) {

????????????? // TODO Auto-generated catch block

????????????? e1.printStackTrace();

?????????? }

?????? }finally{

?????????? try {

????????????? statement.close();

????????????? connectionSQL.close();

?????????? } catch (SQLException e) {

????????????? // TODO Auto-generated catch block

????????????? e.printStackTrace();

?????????? }

??????????

?????? }

这里要说明的就是此处的上下文因为是在一个J2EE环境下调用的，所以改