订阅者-应用程序不使用主题收听ActiveMQ上的消息

Question

我正在尝试引导一个小型用户应用程序，使用gradle和springboot来收听发布到ActiveMQ主题的消息。我注意到，每当我尝试运行该应用程序时，它都无法注册为ActiveMQ上的订阅者，也无法收听发布到主题上的消息。进程在没有堆栈跟踪的情况下终止。但是，在github (Reference-2)上有一个类似的代码库，但使用的是maven构建结构，它似乎连接并接收了ActiveMQ (localhost)上发布的主题消息。我已经调试这个问题很长时间了--我还没能找出根本原因。以下是供参考的代码片段：

如有任何意见，将不胜感激。谢谢!

注意:在Java1.8环境下，所有的运行都是在eclipse内部完成的。

JMSTopicSubscriber.java

@Component
public class JMSTopicSubscriber
{
   @JmsListener(destination = "${jms.enrol.topic.name}")
   public void receiveMessage(Exam exam)
   {
      System.out.println("Received message: " + exam.toString());
   }
}

JMSConfig.java

@EnableJms
@Configuration
@ComponentScan(basePackages = { "experiment.jms.subscriber" })
@PropertySource("classpath:application.properties")
public class JMSConfig
{
   @Value("${spring.activemq.broker-url}")
   String m_activeMQBrokerUrl;

   @Bean
   public ConnectionFactory connectionFactory()
   {
      ActiveMQConnectionFactory cf = new ActiveMQConnectionFactory();
      cf.setBrokerURL(m_activeMQBrokerUrl);
      return cf;
   }

   @Bean
   public JmsListenerContainerFactory<?> jmsListenerContainerFactory()
   {
      DefaultJmsListenerContainerFactory factory = new DefaultJmsListenerContainerFactory(); 
      factory.setPubSubDomain(true);
      factory.setMessageConverter(messageConverter());
      factory.setConnectionFactory(connectionFactory()); 
      return factory; 
   }
   
   @Bean
   public MessageConverter messageConverter()
   {
       MappingJackson2MessageConverter converter = new MappingJackson2MessageConverter();
       converter.setTargetType(MessageType.TEXT);
       converter.setTypeIdPropertyName("_type");
       return converter;
   }
}

ExperimentTopicJmsSubscriberApplication.java

@SpringBootApplication
@ComponentScan(basePackages = { "experiment.jmsSubscriber" })
public class ExperimentTopicJmsSubscriberApplication
{
   public static void main(String[] args)
   {
      SpringApplication.run(ExperimentTopicJmsSubscriberApplication.class, args);
   }
}

build.gradle

plugins {
    id 'org.springframework.boot' version '2.4.1'
    id 'io.spring.dependency-management' version '1.0.10.RELEASE'
    id 'java'
}

group = 'experiment.jms.topic'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

repositories {
    mavenCentral()
}

dependencies {
    implementation 'org.springframework.boot:spring-boot-starter'
    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    
    // ActiveMQ Dependencies. 
    implementation 'org.springframework.boot:spring-boot-starter-activemq'
}

test {
    useJUnitPlatform()
}

application.properties

spring.activemq.broker-url = tcp://localhost:61616

#topic name
jms.enrol.topic.name = allexams

spring.jms.pub-sub-domain=true

##Configure concurrent listeners using the spring.jms.concurrency and spring.jms.max-concurrency properties.
#spring.jms.concurrency property configures the minimum number of concurrent consumers.
spring.jms.listener.concurrency=2

#spring.jms.max-concurrency configures the maximum number of concurrent consumers.
spring.jms.listener.max-concurrency=2

封装结构

​

​

数据模型

    public class Exam implements Serializable
    {
       private String m_examName; 
       private int m_examYear; 
       
       public Exam()
       {
          
       }
       
       public Exam( String examName, int examYear )
       {
          this.m_examName = examName; 
          this.m_examYear = examYear;  
       }
       
       public String getExamName()
       {
          return this.m_examName; 
       }
       
       public int getExamYear()
       {
          return this.m_examYear;
       }
       
       public String toString()
       {
          return "(Exam Name: " + this.m_examName + ", "
                + "Exam Year: " + Integer.toString(this.m_examYear) + ")"; 
       }
     }

参考资料

1. https://github.com/smitha-madhavamurthy/springboot-activemq-subscriber
2. https://grokonez.com/java-integration/activemq-work-spring-jms-activemq-topic-publisher-subcribers-pattern-using-springboot

Answer 1

我通过删除显式组件扫描注释标签解决了这个问题。现在，订阅者应用程序在activemq上收听主题。