你好,世界
以下是一个非常简单的 JMS 应用程序,具有多个并发消费者和生产者。有关如何正确设置类路径的详细信息,请参见初始配置指南。
运行此示例后您可能需要做的事情
- 设置代理,而不是直接使用 org.activemq.broker.impl.Main 类。
- 使用 JNDI 查找 javax.jms.ConnectionFactory,而不是直接创建 ActiveMQConnectionFactory。
- 实现 javax.jms.MessageListener 接口,而不是调用 consumer.receive()。
- 使用事务性会话
- 使用主题而不是队列
此示例的目的是向您展示以简单明了的方式使用 JMS 所需的基本代码。消费者和生产者可以非常轻松地在完全不同的机器或不同的进程中。
App.java
import org.apache.activemq.ActiveMQConnectionFactory;
import javax.jms.Connection;
import javax.jms.DeliveryMode;
import javax.jms.Destination;
import javax.jms.ExceptionListener;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
/**
* Hello world!
*/
public class App {
public static void main(String\[\] args) throws Exception {
thread(new HelloWorldProducer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
Thread.sleep(1000);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
Thread.sleep(1000);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldProducer(), false);
Thread.sleep(1000);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldConsumer(), false);
thread(new HelloWorldProducer(), false);
}
public static void thread(Runnable runnable, boolean daemon) {
Thread brokerThread = new Thread(runnable);
brokerThread.setDaemon(daemon);
brokerThread.start();
}
public static class HelloWorldProducer implements Runnable {
public void run() {
try {
// Create a ConnectionFactory
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://127.0.0.1");
// Create a Connection
Connection connection = connectionFactory.createConnection();
connection.start();
// Create a Session
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
// Create the destination (Topic or Queue)
Destination destination = session.createQueue("TEST.FOO");
// Create a MessageProducer from the Session to the Topic or Queue
MessageProducer producer = session.createProducer(destination);
producer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
// Create a messages
String text = "Hello world! From: " + Thread.currentThread().getName() + " : " + this.hashCode();
TextMessage message = session.createTextMessage(text);
// Tell the producer to send the message
System.out.println("Sent message: "+ message.hashCode() + " : " + Thread.currentThread().getName());
producer.send(message);
// Clean up
session.close();
connection.close();
}
catch (Exception e) {
System.out.println("Caught: " + e);
e.printStackTrace();
}
}
}
public static class HelloWorldConsumer implements Runnable, ExceptionListener {
public void run() {
try {
// Create a ConnectionFactory
ActiveMQConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://127.0.0.1");
// Create a Connection
Connection connection = connectionFactory.createConnection();
connection.start();
connection.setExceptionListener(this);
// Create a Session
Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
// Create the destination (Topic or Queue)
Destination destination = session.createQueue("TEST.FOO");
// Create a MessageConsumer from the Session to the Topic or Queue
MessageConsumer consumer = session.createConsumer(destination);
// Wait for a message
Message message = consumer.receive(1000);
if (message instanceof TextMessage) {
TextMessage textMessage = (TextMessage) message;
String text = textMessage.getText();
System.out.println("Received: " + text);
} else {
System.out.println("Received: " + message);
}
consumer.close();
session.close();
connection.close();
} catch (Exception e) {
System.out.println("Caught: " + e);
e.printStackTrace();
}
}
public synchronized void onException(JMSException ex) {
System.out.println("JMS Exception occured. Shutting down client.");
}
}
}