如何使用Apache Camel浏览队列中的消息？

Question

我需要使用驼峰路由浏览来自活动mq的消息，而不使用这些消息。

JMS队列中的消息将被读取（仅浏览而不使用）并移动到数据库中，同时确保原始队列保持完整。

public class CamelStarter {

   private static CamelContext camelContext;

            public static void main(String[] args) throws Exception {
                            camelContext = new DefaultCamelContext();
                            ConnectionFactory connectionFactory = new ActiveMQConnectionFactory(ActiveMQConnectionFactory.DEFAULT_BROKER_URL);

                            camelContext.addComponent("jms",  JmsComponent.jmsComponent(connectionFactory));

                            camelContext.addRoutes(new RouteBuilder() {

                                            @Override
                                            public void configure() throws Exception {
                                                from("jms:queue:testQueue").to("browse:orderReceived") .to("jms:queue:testQueue1");
                                            }

                                            }
                            );

                            camelContext.start();

                            Thread.sleep(1000);

                             inspectReceivedOrders();

                            camelContext.stop();

            }

公共静态无效检查ReceivedOrders（）{

BrowsableEndpoint browse = camelContext.getEndpoint("browse:orderReceived", BrowsableEndpoint.class);
List<Exchange> exchanges = browse.getExchanges();
System.out.println("Browsing queue: "+ browse.getEndpointUri() + " size: " + exchanges.size());
for (Exchange exchange : exchanges) {
  String payload = exchange.getIn().getBody(String.class);
  String msgId = exchange.getIn().getHeader("JMSMessageID", String.class);
  System.out.println(msgId + "=" +payload);

}

Answer 1

据我所知，不可能在骆驼阅读（不消费！）JMS消息：-（我（在JEE应用程序中）找到的唯一解决方法是使用计时器定义启动EJB，持有QueueBrowser，并将消息处理委托给驼峰路由：

@Singleton
@Startup
public class MyQueueBrowser  {

    private TimerService timerService;

    @Resource(mappedName="java:/jms/queue/com.company.myqueue")
    private Queue sourceQueue;

    @Inject
    @JMSConnectionFactory("java:/ConnectionFactory")
    private JMSContext jmsContext;  

    @Inject
    @Uri("direct:readMessage")
    private ProducerTemplate camelEndpoint;


    @PostConstruct
    private void init() {       
        TimerConfig timerConfig = new TimerConfig(null, false);
        ScheduleExpression se = new ScheduleExpression().hour("*").minute("*/"+frequencyInMin);
        timerService.createCalendarTimer(se, timerConfig);
    }


    @Timeout
    public void scheduledExecution(Timer timer) throws Exception {      
        QueueBrowser browser = null;
        try {                       
            browser = jmsContext.createBrowser(sourceQueue);                                           
            Enumeration<Message> msgs = browser.getEnumeration();
            while ( msgs.hasMoreElements() ) { 
                Message jmsMsg = msgs.nextElement(); 
                // + here: read body and/or properties of jmsMsg                                            
                camelEndpoint.sendBodyAndHeader(body, myHeaderName, myHeaderValue);
            }                                                                               
        } catch (JMSRuntimeException jmsException) {
            ...
        } finally {        
            browser.close();
        }
    }


}

Answer 2

Apache camel browse组件正是为此而设计的。在这里查看文档。

因为您没有提供任何其他信息，所以不能再多说了。

假设你有这样的路线

from("activemq:somequeue).to("bean:someBean")  

或者

from("activemq:somequeue).process(exchange -> {})  

你所要做的就是像这样在两者之间放置一个浏览endpoint

from("activemq:somequeue).to("browse:someHandler").to("bean:someBean")   

然后写一个这样的类

@Component
public class BrowseQueue {

  @Autowired
  CamelContext camelContext;

  public void inspect() {
    BrowsableEndpoint browse = camelContext.getEndpoint("browse:someHandler", BrowsableEndpoint.class);
    List<Exchange> exchanges = browse.getExchanges();


    for (Exchange exchange : exchanges) {
      ...... 
    }
  }

}