In this post I’m going to show you how to configure a JMS message selector using Spring JMS.
You’ll also see how to add information to a message so that you can select it.
So here we go.
If you want to learn more about Spring JMS – head on over to the Spring JMS tutorials page.
1. What is a JMS Message Selector?
If your messaging application needs to filter the messages it receives, you can use a JMS message selector. It allows a message consumer to specify the messages it is interested in.
A selector is a String that contains an expression. The syntax of the expression is based on a subset of the SQL92 conditional expression syntax.
Let’s create an example to show how all of this works. We start from a previous Spring JMS configuration example.
We then modify the Receiver so that it receives high and low priority messages with different listeners. In the Sender we add a JMS property on which we can filter.
2. General Project Overview
We will use the following tools/frameworks:
- Spring JMS 5.1
- Spring Boot 2.1
- ActiveMQ 5.15
- Maven 3.6
Our project has the following directory structure:
3. Add a JMS Message Selector to a Listener
On the @JmsListener there is an optional message selector property you can define.
We create two listeners in the Receiver: one for high priority messages and one for low priority messages. Selection is done based on a priority JMS property that we will set in the Sender.
Note that a message consumer receives only messages whose headers and properties match the selector.
A message selector cannot select messages on the basis of the content of the message body.
package com.codenotfound.jms;
import java.util.concurrent.CountDownLatch;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.jms.annotation.JmsListener;
import org.springframework.stereotype.Component;
@Component
public class Receiver {
private static final Logger LOGGER =
LoggerFactory.getLogger(Receiver.class);
private CountDownLatch latch = new CountDownLatch(2);
public CountDownLatch getLatch() {
return latch;
}
@JmsListener(destination = "${queue.boot}",
selector = "priority = 'high'")
public void receiveHigh(String message) {
LOGGER.info("received high priority message='{}'", message);
latch.countDown();
}
@JmsListener(destination = "${queue.boot}",
selector = "priority = 'low'")
public void receiveLow(String message) {
LOGGER.info("received low priority message='{}'", message);
latch.countDown();
}
}The JmsTemplate by default converts a String into a TextMessage using the SimpleMessageConverter. For more information on this you can check the Spring JMS MessageConverter example.
We can use a MessagePostProcessor to add a JMS property to a message after it has been processed by the converter.
Modify the Sender to check an isHighPriority parameter. If the value equals true, a priority property with the value high is set. Otherwise the property is set to low.
package com.codenotfound.jms;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.stereotype.Component;
@Component
public class Sender {
private static final Logger LOGGER =
LoggerFactory.getLogger(Sender.class);
@Autowired
private JmsTemplate jmsTemplate;
public void send(String destination, String message,
boolean isHighPriority) {
LOGGER.info("sending message='{}' with highPriority='{}'",
message, isHighPriority);
if (isHighPriority) {
jmsTemplate.convertAndSend(destination, message,
messagePostProcessor -> {
messagePostProcessor.setStringProperty("priority",
"high");
return messagePostProcessor;
});
} else {
jmsTemplate.convertAndSend(destination, message,
messagePostProcessor -> {
messagePostProcessor.setStringProperty("priority",
"low");
return messagePostProcessor;
});
}
}
}4. Test the Message Filter
We modify the existing test case so that three messages are sent.
Two of them are set with a high priority and will lower the CountDownLatch in the Receiver.
package com.codenotfound.jms;
import static org.assertj.core.api.Assertions.assertThat;
import java.util.concurrent.TimeUnit;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.annotation.DirtiesContext;
import org.springframework.test.context.junit4.SpringRunner;
@RunWith(SpringRunner.class)
@SpringBootTest
@DirtiesContext
public class SpringJmsApplicationTest {
@Autowired
private Sender sender;
@Autowired
private Receiver receiver;
@Test
public void testReceive() throws Exception {
sender.send("selector.q", "High priority 1!", true);
sender.send("selector.q", "Low priority 1!", false);
sender.send("selector.q", "High priority 2!", true);
receiver.getLatch().await(10000, TimeUnit.MILLISECONDS);
assertThat(receiver.getLatch().getCount()).isEqualTo(0);
}
}Open a command prompt in the root directory and start the test case.
mvn testIn the output logs, we can see that the messages are received in the respective JMS Listeners.
. ____ _ __ _ _
/// / ___'_ __ _ _(_)_ __ __ _ / / / /
( ( )/___ | '_ | '_| | '_ // _` | / / / /
/// ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_/__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.1.5.RELEASE)
2019-05-30 17:24:00.512 INFO 13808 --- [ main] c.c.jms.SpringJmsApplicationTest : Starting SpringJmsApplicationTest on DESKTOP-2RB3C1U with PID 13808 (started by Codenotfound in C:/Users/Codenotfound/repos/spring-jms/spring-jms-message-selector)
2019-05-30 17:24:00.514 INFO 13808 --- [ main] c.c.jms.SpringJmsApplicationTest : No active profile set, falling back to default profiles: default
2019-05-30 17:24:01.946 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Using Persistence Adapter: MemoryPersistenceAdapter
2019-05-30 17:24:02.024 INFO 13808 --- [ JMX connector] o.a.a.broker.jmx.ManagementContext : JMX consoles can connect to service:jmx:rmi:///jndi/rmi://localhost:1099/jmxrmi
2019-05-30 17:24:02.095 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.15.9 (localhost, ID:DESKTOP-2RB3C1U-59760-1559229841967-0:1) is starting
2019-05-30 17:24:02.104 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.15.9 (localhost, ID:DESKTOP-2RB3C1U-59760-1559229841967-0:1) started
2019-05-30 17:24:02.104 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : For help or more information please see: http://activemq.apache.org
2019-05-30 17:24:02.134 INFO 13808 --- [ main] o.a.activemq.broker.TransportConnector : Connector vm://localhost started
2019-05-30 17:24:02.184 INFO 13808 --- [ main] c.c.jms.SpringJmsApplicationTest : Started SpringJmsApplicationTest in 2.106 seconds (JVM running for 3.165)
2019-05-30 17:24:02.515 INFO 13808 --- [ main] com.codenotfound.jms.Sender : sending message='High priority 1!' with highPriority='true'
2019-05-30 17:24:02.533 INFO 13808 --- [ main] com.codenotfound.jms.Sender : sending message='Low priority 1!' with highPriority='false'
2019-05-30 17:24:02.536 INFO 13808 --- [ main] com.codenotfound.jms.Sender : sending message='High priority 2!' with highPriority='true'
2019-05-30 17:24:02.539 INFO 13808 --- [enerContainer-1] com.codenotfound.jms.Receiver : received low priority message='Low priority 1!'
2019-05-30 17:24:02.539 INFO 13808 --- [enerContainer-1] com.codenotfound.jms.Receiver : received high priority message='High priority 1!'
2019-05-30 17:24:02.542 INFO 13808 --- [enerContainer-1] com.codenotfound.jms.Receiver : received high priority message='High priority 2!'
2019-05-30 17:24:03.558 INFO 13808 --- [ main] o.a.activemq.broker.TransportConnector : Connector vm://localhost stopped
2019-05-30 17:24:03.558 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.15.9 (localhost, ID:DESKTOP-2RB3C1U-59760-1559229841967-0:1) is shutting down
2019-05-30 17:24:03.567 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.15.9 (localhost, ID:DESKTOP-2RB3C1U-59760-1559229841967-0:1) uptime 1.885 seconds
2019-05-30 17:24:03.568 INFO 13808 --- [ main] o.apache.activemq.broker.BrokerService : Apache ActiveMQ 5.15.9 (localhost, ID:DESKTOP-2RB3C1U-59760-1559229841967-0:1) is shutdown
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 4.161 s - in com.codenotfound.jms.SpringJmsApplicationTest
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 1, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 9.207 s
[INFO] Finished at: 2019-05-30T17:24:04+02:00
[INFO] ------------------------------------------------------------------------
If you would like to run the above code sample you can get the full source code here.
Setting up a JMS message selector is straightforward when you use Spring JMS.
Make sure to leave a comment if the example was helpful.
Thanks!
原创文章，作者：ItWorker，如若转载，请注明出处：https://blog.ytso.com/tech/java/271582.html