说明
基于ActiveMQ学习（二），学习ActiveMQ的另一种消息模式Topic订阅模式，同时将普通的文本消息改为对象消息。
代码
订阅模式
文件目录
- 编写被收发的对象 UserModel
package com.sima.topics;
import java.io.Serializable;
/**
* Created by Maple on 2017-05-28.
*/
public class UserModel implements Serializable {
private String name;
private int age;
public UserModel() {
}
public UserModel(String name, int age) {
this.name = name;
this.age = age;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
@Override
public String toString() {
return "UserModel{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}
}
注：被收发的对象类需要实现Serializable
- 编写消息生产者
package com.sima.topics;
import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import org.apache.activemq.command.ActiveMQObjectMessage;
import javax.jms.*;
/**
* Created by Maple on 2017-05-28.
*/
public class JMSProducer {
private static final String USERNAME = ActiveMQConnection.DEFAULT_USER; // 默认的连接用户名
private static final String PASSWORD = ActiveMQConnection.DEFAULT_PASSWORD; // 默认的连接密码
private static final String BROKEURL = ActiveMQConnection.DEFAULT_BROKER_URL; // 默认的连接地址
// private static final String BROKEURL= "tcp://localhost:8161"; // 默认的连接地址
private static final int SENDNUM = 3; // 发送的消息数量
public static void main(String[] args){
// ConnectionFactory connectionFactory; // 连接工厂
ActiveMQConnectionFactory connectionFactory; // 连接工厂
Connection connection = null; // 连接
Session session; // 会话 接受或者发送消息的线程
Destination destination; // 消息的目的地
MessageProducer messageProducer; // 消息生产者
connectionFactory = new ActiveMQConnectionFactory(JMSProducer.USERNAME,
JMSProducer.PASSWORD, JMSProducer.BROKEURL);
connectionFactory.setTrustAllPackages(true);
try {
connection = connectionFactory.createConnection(); // 通过连接工厂获取连接
connection.start(); // 启动连接
session = connection.createSession(Boolean.TRUE, Session.AUTO_ACKNOWLEDGE); // 创建Session
// destination = session.createQueue("TestQueueFirst"); // 创建消息队列
destination = session.createTopic("TestTopicFirst"); // 创建消息队列
messageProducer = session.createProducer(destination); // 创建消息生产者
//设置不持久化
// messageProducer.setDeliveryMode(DeliveryMode.NON_PERSISTENT);
sendMessage(session, messageProducer); // 发送消息
session.commit();
} catch (JMSException e) {
e.printStackTrace();
}finally {
if(connection!=null){
try {
connection.close();
} catch (JMSException e) {
e.printStackTrace();
}
}
}
}
private static void sendMessage(Session session, MessageProducer messageProducer) {
for(int i=0;i< JMSProducer.SENDNUM;i++){
TextMessage message= null;
try {
// message = session.createTextMessage("ActiveMQ 发送的消息-"+i);
// System.out.println("发送消息：" + "ActiveMQ 发送的消息-" + i);
// messageProducer.send(message);
UserModel userModel = new UserModel("maple", 28);
ObjectMessage objectMessage = session.createObjectMessage(userModel);
objectMessage.setObject(userModel);
// ActiveMQObjectMessage
System.out.println("发送消息：" + "ActiveMQ 发送的消息-" + userModel.toString());
messageProducer.send(objectMessage);
} catch (JMSException e) {
e.printStackTrace();
}
}
}
}
- 消息消费者
package com.sima.topics;
import com.sima.queues.MyListener;
import org.apache.activemq.ActiveMQConnection;
import org.apache.activemq.ActiveMQConnectionFactory;
import javax.jms.*;
/**
* Created by Maple on 2017-05-28.
*/
public class JMSConsumerByListener1 {
private static final String USERNAME = ActiveMQConnection.DEFAULT_USER; // 默认的连接用户名
private static final String PASSWORD = ActiveMQConnection.DEFAULT_PASSWORD; // 默认的连接密码
private static final String BROKEURL = ActiveMQConnection.DEFAULT_BROKER_URL; // 默认的连接地址
// private static final String BROKEURL= "tcp://localhost:8161"; // 默认的连接地址
public static void main(String[] args){
// ConnectionFactory connectionFactory; // 连接工厂
ActiveMQConnectionFactory connectionFactory; // 连接工厂
Connection connection = null; // 连接
Session session; // 会话 接受或者发送消息的线程
Destination destination; // 消息的目的地
MessageConsumer messageConsumer; // 消息的消费者
// 实例化连接工厂
connectionFactory=new ActiveMQConnectionFactory(JMSConsumerByListener1.USERNAME, JMSConsumerByListener1.PASSWORD, JMSConsumerByListener1.BROKEURL);
connectionFactory.setTrustAllPackages(true);
try {
connection=connectionFactory.createConnection(); // 通过连接工厂获取连接
connection.start(); // 启动连接
session=connection.createSession(Boolean.FALSE, Session.AUTO_ACKNOWLEDGE); // 创建Session
// destination=session.createQueue("TestQueueFirst"); // 创建连接的消息队列
destination=session.createTopic("TestTopicFirst"); // 创建连接的消息队列
messageConsumer=session.createConsumer(destination); // 创建消息消费者
// messageConsumer.setMessageListener(new MyListener());// 注册消息监听
messageConsumer.setMessageListener(new MyObjectListener());// 注册消息监听
} catch (JMSException e) {
e.printStackTrace();
}
}
}
- 监听类
package com.sima.topics;
import javax.jms.*;
/**
* Created by Maple on 2017-05-28.
*/
public class MyObjectListener implements MessageListener {
public void onMessage(Message message) {
try {
UserModel u = (UserModel) ((ObjectMessage) message).getObject();
System.out.println("通过MyListener收到的ObjectMessage消息："+ u.toString());
} catch (JMSException e) {
e.printStackTrace();
}
}
}
- 先运行消费者类进行消息订阅，查看 http://localhost:8161/admin/subscribers.jsp
订阅者
注册成消费者
- 运行消息生产者，此时消费者会收到通知并进行消费
消息订阅消费
- 当有多个订阅者的情况下，每个订阅者都将收到相同数量的消息
白名单
ActiveMQ自5.12.2版本之后，强制用户指定一份可信任的packages白名单，以对付ObjectMessage存在的安全漏洞。具体内容可参考：http://activemq.apache.org/objectmessage.html。
会遇到如下问题：
javax.jms.JMSException: Failed to build body from content. Serializable class not available to broker. Reason: java.lang.ClassNotFoundException: Forbidden class com.sima.topics.UserModel!
This class is not trusted to be serialized as ObjectMessage payload.
Please take a look at http://activemq.apache.org/objectmessage.html for more information on how to configure trusted classes.
官方提供的白名单配置方法如下：
白名单配置
