Question

我有一个Java服务，该服务从Oracle Advanced Queue获取消息。我可以创建连接并收听并获取消息。我可以看到您可以停止并开始侦听消息，因此我已经为此实现了控件。但是，我希望能够报告侦听器的当前状态。我可以看到它是否存在，但是如何知道它是停止还是启动？

我有一个类似的容器类（Listener是我自己的类（同时实现MessageListener和ExceptionListener），实际上对消息有作用）

public class QueueContainer {
  private static final String QUEUE_NAME = "foo";

  private final Connection dbConnection;
  private final QueueConnection queueConnection;
  private final QueueSession queueSession;
  private final Queue queue;
  private final MessageConsumer consumer;
  private final Listener listener;

public QueueContainer(final Connection dbConnection ) {
    try {
      this.dbConnection = dbConnection;
      queueConnection = AQjmsQueueConnectionFactory.createQueueConnection(dbConnection);
      queueSession = queueConnection.createQueueSession(false, Session.CLIENT_ACKNOWLEDGE);
      queue = ((AQjmsSession) queueSession).getQueue(context.getEnvironment(), QUEUE_NAME);
      consumer = queueSession.createConsumer(queue);
      listener = new Listener(QUEUE_NAME);
      consumer.setMessageListener(listener);
      queueConnection.setExceptionListener(listener);
    } catch (JMSException | SQLException e) {
      throw new RunTimeException("Queue Exception", e);
    }
  }
  public void startListening() {
    try {
      queueConnection.start();

    } catch (JMSException e) {
      throw new RunTimeException("Failed to start listening to queue", e);
    }
  }

  public void stopListening() {
    try {
      queueConnection.stop();
    } catch (JMSException e) {
      throw new RunTimeException("Failed to stop listening to queue", e);
    }
  }

  public void close() {
    if (queueConnection != null) {
      try {
        queueConnection.close();
      } catch (JMSException e) {
        throw new RunTimeException("Failed to stop listening to queue", e);
      }
    }
  }

  public boolean isRunning() {
    try {
      // This doesn't work - I can't distinguish between started and stopped
      return queueConnection.getClientID() != null;
    } catch (JMSException e) {
      LOGGER.warn("Failed to get queue client ID", e);
      return false;
    }
  }

我看不到要插入isRunning的内容以区分已停止的侦听器和开始的侦听器

Answer 1

没有JMS API调用来确定是否启动javax.jms.Connection。

要清楚，队列本身不是已启动或已停止的实体。连接已启动或停止。

您可能可以从Oracle Advanced Queue实现对象获取此信息，但是我对该实现不熟悉，所以我不能说。显然，任何使用实现对象而不是标准API的解决方案都是不可移植的。

Answer 2

JMS API假定您了解自己的所作所为。那么，为什么不添加一个布尔标志并跟踪呢？

    private volatile boolean isListening = false;
    ...

    public void startListening() {
    try {
      queueConnection.start();
      isListening = true;
    } catch (JMSException e) {
      throw new RunTimeException("Failed to start listening to queue", e);
    }
  }

  public void stopListening() {
    try {
      queueConnection.stop();
      isListening = false;
    } catch (JMSException e) {
      throw new RunTimeException("Failed to stop listening to queue", e);
    }
  }

  public void close() {
    if (queueConnection != null) {
      try {
        queueConnection.close();
        isListening = false;
      } catch (JMSException e) {
        throw new RunTimeException("Failed to stop listening to queue", e);
      }
    }
  }

  public boolean isRunning() {
      return isListening;
  }

如何判断JMS队列是启动还是停止？

2 个答案: