ActiveMQ忽略优先级设置

Question

使用此代码：

import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.broker.BrokerService;
import org.apache.activemq.broker.region.policy.PolicyEntry;
import org.apache.activemq.broker.region.policy.PolicyMap;
import org.apache.activemq.command.ActiveMQDestination;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
public class CompositeQueuePriority {
public static void main(String[] args) throws Exception {
String brokerUrl = "tcp://localhost:61616";
BrokerService broker = new BrokerService();
broker.addConnector(brokerUrl);
broker.setPersistent(false);
broker.setDestinationPolicy(policyMap());
broker.start();
Destination a = ActiveMQDestination.createDestination("queue", ActiveMQDestination.QUEUE_TYPE);
Session session = createSession();
MessageProducer lowProducer = session.createProducer(a);
lowProducer.setPriority(1);
MessageProducer highProducer = session.createProducer(a);
highProducer.setPriority(9);
MessageConsumer consumer = session.createConsumer(a);
for (int i = 0; i < 10; i++) {
lowProducer.send(session.createTextMessage("Low"));
highProducer.send(session.createTextMessage("High"));
String first = ((TextMessage) consumer.receive()).getText();
String second = ((TextMessage) consumer.receive()).getText();
System.out.println(first + ", " + second);
}
broker.stop();
}
private static Session createSession() throws JMSException {
ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("vm://localhost");
Connection connection = connectionFactory.createConnection();
connection.start();
return connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
}
private static PolicyMap policyMap() {
PolicyMap policyMap = new PolicyMap();
policyMap.setDefaultEntry(prioPolicyEntry());
return policyMap;
}
private static PolicyEntry prioPolicyEntry() {
PolicyEntry policyEntry = new PolicyEntry();
policyEntry.setPrioritizedMessages(true);
return policyEntry;
}
}

输出为：

Low, High
Low, High
Low, High
Low, High
Low, High
Low, High
Low, High
Low, High
Low, High
Low, High

根据文档，从5.4开始支持优先级，我使用的是5.15。我做错什么了吗？

Answer 1

我认为您的问题是，当您发送消息时，消费者已经创建，这意味着一旦代理收到消息，就会立即将消息发送给消费者，因此这些消息将没有机会按优先级使用。

先发送所有消息，然后创建您的消费者。