Chapter 3. Getting started

This chapter guides you through the steps to set up your environment and run a simple messaging program.

3.1. Prerequisites

3.2. Running Hello World

The Hello World example creates a connection to the broker, sends a message containing a greeting to the example queue, and receives it back. On success, it prints the received message to the console.

Example: Sending and receiving "Hello World!" - HelloWorld.java

package net.example;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.jms.annotation.EnableJms;
import org.springframework.jms.annotation.JmsListener;
import org.springframework.jms.core.JmsTemplate;

@EnableJms
@SpringBootApplication
public class HelloWorld implements CommandLineRunner {
    @Autowired
    private JmsTemplate jmsTemplate;

    public static void main(String[] args) {
        SpringApplication.run(HelloWorld.class, args);
    }

    @Override
    public void run(String... strings) throws Exception {
        sendMessage("Hello World!");
    }

    public void sendMessage(String text) {
        System.out.println(String.format("Sending '%s'", text));
        this.jmsTemplate.convertAndSend("example", text);
    }

    @JmsListener(destination = "example")
    public void receiveMessage(String text) {
        System.out.println(String.format("Received '%s'", text));
    }
}

Running the example

To compile and run the example program, use the following procedure:

Procedure

  1. Create a new project directory. This is referred to as <project-dir> in the steps that follow.

  2. Copy the example listing to the following location: 

    <project-dir>/src/main/java/net/example/HelloWorld.java

  3. Use a text editor to create a new <project-dir>/pom.xml file. Add the following XML to it: 

    <project>
  <modelVersion>4.0.0</modelVersion>

  <groupId>net.example</groupId>
  <artifactId>example</artifactId>
  <version>1.0.0-SNAPSHOT</version>

  <parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.2.7.RELEASE</version>
  </parent>

  <dependencies>
    <dependency>
      <groupId>org.amqphub.spring</groupId>
      <artifactId>amqp-10-jms-spring-boot-starter</artifactId>
      <version>2.2.7.redhat-00002</version>
    </dependency>
  </dependencies>

  <build>
    <plugins>
      <plugin>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-maven-plugin</artifactId>
      </plugin>
    </plugins>
  </build>
</project>

  4. Change to the project directory and use the mvn command to compile the program. 

    $ mvn clean package

  5. Use the java command to run the program. 

    $ java -jar target/example-1.0.0-SNAPSHOT.jar

    Running the Hello World example results in the following console output: 

    $ java -jar target/example-1.0.0-SNAPSHOT.jar

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.5.RELEASE)

[...]
2018-11-05 16:21:09.849  INFO 14805 --- [main] net.example.HelloWorld: Started HelloWorld in 1.074 seconds (JVM running for 1.38)
Sending 'Hello World!'
Received 'Hello World!'

3.3. Additional examples

More example programs are available from the AMQP 1.0 JMS Spring Boot project and the Spring project.