1
我想运行下面的程序。我使用glassfish server 3.1.2来启用这个MDB运行。然后我无法运行它。运行一个简单的MDB应用程序时出错
package com.mdb;
import javax.jms.ConnectionFactory;
import javax.jms.Queue;
import javax.jms.Connection;
import javax.jms.Session;
import javax.jms.QueueBrowser;
import javax.jms.Message;
import javax.jms.JMSException;
import javax.annotation.Resource;
import java.util.Enumeration;
import javax.ejb.Stateless;
/**
* The MessageBrowser class inspects a queue and displays the messages it
* holds.
*/
@Stateless
public class MessageClient {
@Resource(mappedName = "jms/ConnectionFactory")
private static ConnectionFactory connectionFactory;
@Resource(mappedName = "jms/Queue")
private static Queue queue;
/**
* Main method.
*
* @param args the queue used by the example
*/
public static void main(String[] args) {
Connection connection = null;
try {
System.out.println("1");
connection = connectionFactory.createConnection();
System.out.println("2");
Session session = connection.createSession(
false,
Session.AUTO_ACKNOWLEDGE);
QueueBrowser browser = session.createBrowser(queue);
Enumeration msgs = browser.getEnumeration();
if (!msgs.hasMoreElements()) {
System.out.println("No messages in queue");
} else {
while (msgs.hasMoreElements()) {
Message tempMsg = (Message) msgs.nextElement();
System.out.println("Message: " + tempMsg);
}
}
} catch (JMSException e) {
System.err.println("Exception occurred: " + e.toString());
} finally {
if (connection != null) {
try {
connection.close();
} catch (JMSException e) {
}
}
}
}
}
问题是我在运行它时遇到了下面的错误。
Exception in thread "main" java.lang.NullPointerException
at com.mdb.MessageClient.main(MessageClient.java:35)
这里可能是什么问题?
你的connectionFactory可能是NULL – 2013-02-18 08:41:51