JMS队列接收消息？

Question

JMS队列接收消息？

7

在JMS API文档中，它说：

public Message receive() throws JMSException
Receives the next message produced for this message consumer. This call blocks indefinitely until a message is produced or until this message consumer is closed.

If this receive is done within a transaction, the consumer retains the message until the transaction commits.

我是一个有用的助手，可以翻译文本。

这里有三个问题： 1. 在代码中，我们需要使用while循环来接收消息吗？例如：

while(true){
    Message msg = queue.receive();
    ....
}

what is the transaction setting ? how to commit a transaction ? like this:

boolean transacted = false;
session = connection.createQueueSession(transacted, Session.AUTO_ACKNOWLEDGE);

receiveNoWait() has transaction support ? how to use it ?

谢谢

- user595234

1个回答

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- gregwhitaker · Accepted Answer

如果您要使用receive，则需要一些循环来保持在接收到第一个消息后继续接收消息。请记住，您还可以设置messagelistener并通过回调方法异步获取接收的消息，而无需阻塞。
默认情况下，事务通常设置为AUTO_ACKNOWLEDGE，这意味着从队列中获取消息后就会消失，无法回滚。如果要设置事务，则需要将会话设置为事务性，并将方法设置为SESSION_TRANSACTED。当您在会话上调用commit（）时，消息将在队列上确认。
如果正确设置了确认模式并在会话上使用commit（）和rollback（），则receiveNoWait（）可以具有事务支持。

如果我是您，我会创建一个MessageListener，而不必担心旋转线程来轮询接收方法。请注意，一旦创建会话，隐式事务即开始。

public class JmsAdapter implements MessageListener, ExceptionListener
{
    private ConnectionFactory connFactory = null;
    private Connection conn = null;
    private Session session = null;

    public void receiveMessages() 
    {
        try
        {
            this.session = this.conn.createSession(true, Session.SESSION_TRANSACTED);

            this.conn.setExceptionListener(this);

            Destination destination = this.session.createQueue("SOME_QUEUE_NAME");

            this.consumer = this.session.createConsumer(destination);

            this.consumer.setMessageListener(this);

            this.conn.start();
        } 
        catch (JMSException e) 
        {
            //Handle JMS Exceptions Here
        }
    }

    @Override
    public void onMessage(Message message) 
    {
        try
        {
            //Do Message Processing Here

            //Message sucessfully processed...  Go ahead and commit the transaction.
            this.session.commit();
        }
        catch(SomeApplicationException e)
        {
            //Message processing failed.
            //Do whatever you need to do here for the exception.

            //NOTE: You may need to check the redelivery count of this message first
            //and just commit it after it fails a predefined number of times (Make sure you
            //store it somewhere if you don't want to lose it).  This way you're process isn't
            //handling the same failed message over and over again.
            this.session.rollback()
        }
    }
}