[英]unable to receive messages from queue in jms
我是jms的初学者,我只是想让一个运行简单的Web应用程序运行,该应用程序可以生成和使用消息。 所以在我的欢迎页面上,我有一个带有文本框和提交按钮的表单。 在提交时,文本框中的文本将包装在一条消息中,并通过MessageProducer发送到服务器上的队列。 据我了解,此消息应保留在队列中,直到我从某个消费者连接到该队列的MessageConsumer调用receive方法。 不幸的是,在第二个jsp页面上,我单击“获取消息”按钮,收到的消息变为null。 我很确定他们被正确发送了(至少没有错误的说法)有没有办法我可以检查一下? 关于出什么问题有什么想法吗? 提前致谢。 生产者/消费者代码。
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;
}
}
抱歉,在另一个问题中找到了答案。MessageConsumer 不使用消息 ..我所需要做的就是在getFromQueue方法之前调用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");
}
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