我已经在ActiveMQ conf / activemq.xml中配置了许多启动时可用的目标。我可以看到在ActiveMQ Web控制台上创建了队列和主题。现在我想使用相同的队列和主题通过我的Java程序使用JMS进行消息交换。以下是我正在使用的代码。但是，我无法在ActiveMQ Web控制台的主题中看到任何已排队的消息。
package com.test;
import javax.jms.Connection;
import javax.jms.ConnectionFactory;
import javax.jms.Destination;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageProducer;
import javax.jms.Session;
import javax.jms.TextMessage;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import org.apache.log4j.BasicConfigurator;
public class Main {
public static void main(String[] args) {
BasicConfigurator.configure();
Destination destination =null;
String destinationName = "MyTopic";
final int numMsgs;
Context jndiContext = null;
// producer details
ConnectionFactory connectionFactory = null;
Connection connection = null;
Session session = null;
MessageProducer producer = null;
//consumer details
ConnectionFactory consumerConnectionFactory = null;
Connection consumerConnection = null;
Session consumerSession = null;
MessageConsumer messageConsumer=null;
/*
* Create a JNDI API InitialContext object
*/
try {
jndiContext = new InitialContext();
} catch (NamingException e) {
System.out.println("Could not create JNDI API context: " + e.toString());
System.exit(1);
}
/*
* Look up connection factory and destination.
*/
try {
connectionFactory = (ConnectionFactory) jndiContext.lookup("ConnectionFactory");
destination = (Destination) jndiContext.lookup(destinationName);
} catch (NamingException e) {
System.out.println("JNDI API lookup failed: " + e);
System.exit(1);
}
/*
* Create connection. Create session from connection; false means
* session is not transacted. Create sender and text message. Send
* messages, varying text slightly. Send end-of-messages message.
* Finally, close connection.
*/
try {
connection = connectionFactory.createConnection();
connection.start();
session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE);
producer = session.createProducer(destination);
TextMessage message = session.createTextMessage();
for (int i = 0; i < 2; i++) {
message.setText("This is message " + (i + 1));
System.out.println("Sending message: " + message.getText());
producer.send(message);
}
/*
* Send a non-text control message indicating end of messages.
*/
producer.send(session.createMessage());
/***
* to recieve message
* */
try {
consumerConnectionFactory = (ConnectionFactory) jndiContext.lookup("ConnectionFactory");
consumerConnection = consumerConnectionFactory.createConnection();
consumerConnection.start();
consumerSession = consumerConnection.createSession(false, Session.AUTO_ACKNOWLEDGE);
messageConsumer = consumerSession.createConsumer(destination);
} catch (NamingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
String greeting = "NO_GREETING";
// read a message from the topic destination
Message recievedMessage = messageConsumer.receive();
System.out.println("******************" + recievedMessage);
// check if a message was received
if (recievedMessage != null) {
// cast the message to the correct type
TextMessage textMessage = (TextMessage) recievedMessage;
// retrieve the message content
String text = textMessage.getText();
System.out.println(": received message with text='{}'" + text);
// create greeting
greeting = "Hello " + text + "!";
} else {
System.out.println(": no message received");
}
System.out.println("greeting={}" + greeting);
} catch (JMSException e) {
System.out.println("Exception occurred: " + e);
} finally {
if (connection != null && consumerConnection !=null) {
try {
connection.close();
consumerConnection.close();
} catch (JMSException e) {
}
}
}
}
}
我的JNDI道具文件
java.naming.factory.initial = org.apache.activemq.jndi.ActiveMQInitialContextFactory
# use the following property to configure the default connector
java.naming.provider.url = tcp://localhost:61616/
# use the following property to specify the JNDI name the connection factory
# should appear as.
#connectionFactoryNames = connectionFactory, queueConnectionFactory, topicConnectionFactry
# register some queues in JNDI using the form
# queue.[jndiName] = [physicalName]
queue.MyQueue = example.MyQueue
# register some topics in JNDI using the form
# topic.[jndiName] = [physicalName]
topic.MyTopic = SOME.TOPIC
ActiveMQ / conf / activemq.xml文件中的ActiveMQ配置文件
<!--
Licensed to the Apache Software Foundation (ASF) under one or more
contributor license agreements. See the NOTICE file distributed with
this work for additional information regarding copyright ownership.
The ASF licenses this file to You under the Apache License, Version 2.0
(the "License"); you may not use this file except in compliance with
the License. You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<!-- START SNIPPET: example -->
<beans
xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://activemq.apache.org/schema/core http://activemq.apache.org/schema/core/activemq-core.xsd">
<!-- Allows us to use system properties as variables in this configuration file -->
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<value>file:${activemq.conf}/credentials.properties</value>
</property>
</bean>
<!-- Allows accessing the server log -->
<bean id="logQuery" class="io.fabric8.insight.log.log4j.Log4jLogQuery"
lazy-init="false" scope="singleton"
init-method="start" destroy-method="stop">
</bean>
<!--
The <broker> element is used to configure the ActiveMQ broker.
-->
<broker xmlns="http://activemq.apache.org/schema/core" brokerName="localhost" dataDirectory="${activemq.data}">
<destinations>
<queue physicalName="FOO.BAR" />
<topic physicalName="SOME.TOPIC" />
</destinations>
<destinationPolicy>
<policyMap>
<policyEntries>
<policyEntry topic=">" >
<!-- The constantPendingMessageLimitStrategy is used to prevent
slow topic consumers to block producers and affect other consumers
by limiting the number of messages that are retained
For more information, see:
http://activemq.apache.org/slow-consumer-handling.html
-->
<pendingMessageLimitStrategy>
<constantPendingMessageLimitStrategy limit="1000"/>
</pendingMessageLimitStrategy>
</policyEntry>
</policyEntries>
</policyMap>
</destinationPolicy>
<!--
The managementContext is used to configure how ActiveMQ is exposed in
JMX. By default, ActiveMQ uses the MBean server that is started by
the JVM. For more information, see:
http://activemq.apache.org/jmx.html
-->
<managementContext>
<managementContext createConnector="false"/>
</managementContext>
<!--
Configure message persistence for the broker. The default persistence
mechanism is the KahaDB store (identified by the kahaDB tag).
For more information, see:
http://activemq.apache.org/persistence.html
-->
<persistenceAdapter>
<kahaDB directory="${activemq.data}/kahadb"/>
</persistenceAdapter>
<!--
The systemUsage controls the maximum amount of space the broker will
use before disabling caching and/or slowing down producers. For more information, see:
http://activemq.apache.org/producer-flow-control.html
-->
<systemUsage>
<systemUsage>
<memoryUsage>
<memoryUsage percentOfJvmHeap="70" />
</memoryUsage>
<storeUsage>
<storeUsage limit="100 gb"/>
</storeUsage>
<tempUsage>
<tempUsage limit="50 gb"/>
</tempUsage>
</systemUsage>
</systemUsage>
<!--
The transport connectors expose ActiveMQ over a given protocol to
clients and other brokers. For more information, see:
http://activemq.apache.org/configuring-transports.html
-->
<transportConnectors>
<!-- DOS protection, limit concurrent connections to 1000 and frame size to 100MB -->
<transportConnector name="openwire" uri="tcp://0.0.0.0:61616?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="amqp" uri="amqp://0.0.0.0:5672?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="stomp" uri="stomp://0.0.0.0:61613?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="mqtt" uri="mqtt://0.0.0.0:1883?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
<transportConnector name="ws" uri="ws://0.0.0.0:61614?maximumConnections=1000&wireFormat.maxFrameSize=104857600"/>
</transportConnectors>
<!-- destroy the spring context on shutdown to stop jetty -->
<shutdownHooks>
<bean xmlns="http://www.springframework.org/schema/beans" class="org.apache.activemq.hooks.SpringContextHook" />
</shutdownHooks>
</broker>
<!--
Enable web consoles, REST and Ajax APIs and demos
The web consoles requires by default login, you can disable this in the jetty.xml file
Take a look at ${ACTIVEMQ_HOME}/conf/jetty.xml for more details
-->
<import resource="jetty.xml"/>
</beans>
<!-- END SNIPPET: example -->
在我的输出中，我可以看到下面的文字。
Sending message: This is message 1
Sending message: This is message 2
但是我认为该消息没有放在主题上，因为没有消息显示在ActiveMQ Web控制台上排队。
任何人都可以帮我确定它是否是在java启动时访问ActiveMQ destionation的正确方法。我很清楚如何使用JMS和ActiveMQ通过Java创建队列和主题。但在这个项目中，我想在我的程序中访问现有的队列和主题。
答案 0 :(得分：1)
主题需要有效订阅才能传递消息，否则消息将被删除，这就是发布/订阅的本质。如果您想发送消息并稍后阅读，则应使用队列，或作为最后的手段使用持久主题订阅。如果你懒得谷歌，有很多关于此的教程。