無法從jms的隊列中接收消息

Question

我是jms的初學者，我只是想讓一個運行簡單的Web應用程序運行，該應用程序可以生成和使用消息。 所以在我的歡迎頁面上，我有一個帶有文本框和提交按鈕的表單。 在提交時，文本框中的文本將包裝在一條消息中，並通過MessageProducer發送到服務器上的隊列。 據我了解，此消息應保留在隊列中，直到我從某個消費者連接到該隊列的MessageConsumer調用receive方法。 不幸的是，在第二個jsp頁面上，我單擊“獲取消息”按鈕，收到的消息變為null。 我很確定他們被正確發送了（至少沒有錯誤的說法）有沒有辦法我可以檢查一下？ 關於出什么問題有什么想法嗎？ 提前致謝。 生產者/消費者代碼。

public class Producer {           
    private static final String CONNECTION_FACTORY = "connectionFactory";     
    private static final String CONNECTION_QUEUE = "jms/myqueue";    
    private static final String CONNECTION_TOPIC = "jms/mytopic";     

    public Producer(String message) {         
        ConnectionFactory connectionFactory = null;       
        Connection connection = null;         
        //Get the JNDI Context        
        try {        
            Context jndiContext = new InitialContext();      

            //Create the Connection Factory  and Connection     
            connectionFactory = (ConnectionFactory) jndiContext.lookup(Producer.CONNECTION_FACTORY);       
            connection = connectionFactory.createConnection();  

            //Create the session           
            Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);                   

            publishToQueue(jndiContext, session, message);    
            session.commit();
        } catch (NamingException e) {            
        } catch (JMSException e) {    

        }finally{       
           //close connection     
        }   
    }        

    private void publishToQueue(Context jndiContext, Session session, String message) throws NamingException, JMSException{      
        //Create Queue     
        Queue queue = (Queue) jndiContext.lookup(Producer.CONNECTION_QUEUE); 

        //Create Message Producer       
        MessageProducer producer = session.createProducer(queue);     

        //Send TextMessage        
        producer.setDeliveryMode(DeliveryMode.PERSISTENT);
        TextMessage textMessage = session.createTextMessage();    
        textMessage.setText(message);
        producer.send(textMessage);  
        producer.close();

} 
 } 


public class Consumer {           
    private static final String CONNECTION_FACTORY = "connectionFactory";     
    private static final String CONNECTION_QUEUE = "jms/myqueue";    
    private static final String CONNECTION_TOPIC = "jms/mytopic";     

    private Message message;

    public Consumer() {        
        ConnectionFactory connectionFactory = null;       
        Connection connection = null;         
        //Get the JNDI Context        
        try {        
            Context jndiContext = new InitialContext();     

        //Create the Connection Factory       
        connectionFactory = (ConnectionFactory) jndiContext.lookup(Consumer.CONNECTION_FACTORY);       
        connection = connectionFactory.createConnection();  

        //Create the session           
        Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);                   

        //Call methods to retrieve  message      
        message = getFromQueue(jndiContext, session);    
        session.commit();
        if(message!=null){
            System.out.println("Message Received");
        }
    } catch (NamingException e) {            
        // TODO Auto-generated catch block       
        e.printStackTrace();        
    } catch (JMSException e) {    
        // TODO Auto-generated catch block    
        e.printStackTrace();       

    }finally{       
        try {           
            if(connection != null){    
                connection.close();    
            }            
        } catch (JMSException e) {   
            e.printStackTrace();         
        }       
    }   
}        



private Message getFromQueue(Context jndiContext, Session session) throws NamingException, JMSException{      
    //Create new Queue
    Queue queue = (Queue)jndiContext.lookup(Consumer.CONNECTION_QUEUE);  
    //Create Message Consumer       
    MessageConsumer consumer = session.createConsumer(queue); 
    return consumer.receive(10000);    
}

public Message getMessage(){
    return message;
}
} 

Answer 1

抱歉，在另一個問題中找到了答案。MessageConsumer 不使用消息 ..我所需要做的就是在getFromQueue方法之前調用connection.start（）

 public Consumer() {        
    ConnectionFactory connectionFactory = null;       
    Connection connection = null;         
    //Get the JNDI Context        
    try {        
        Context jndiContext = new InitialContext();     

    //Create the Connection Factory       
    connectionFactory = (ConnectionFactory) jndiContext.lookup(Consumer.CONNECTION_FACTORY);       
    connection = connectionFactory.createConnection();  

    //Create the session           
    Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);                   

    //Call methods to retrieve  message   
     --> connection.start(); <--
    message = getFromQueue(jndiContext, session);    
    session.commit();
    if(message!=null){
        System.out.println("Message Received");
    }