There are two ways to use activemq, as shown in the following figure
Add the jar package of ActiveMQ all to the project.
A producer corresponds to a consumer, and the message produced by the producer disappears after being consumed by the consumer.
Producer code
public void queueProducer() throws Exception{ //1. To create a connection factory object, you need to specify the ip and port of the service ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://192.168.25.161:61616"); //2. Create a Connection object using the factory object Connection connection = connectionFactory.createConnection(); //3. To open a Connection, call the start method of the Connection object connection.start(); //4. Create a Session object //The first parameter: whether to start transaction or not. Generally, transaction is not opened. If transaction is opened, the second parameter is meaningless //The second parameter: response mode, auto response or manual response, general auto response Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); //5. Use Session object to create a Destination object in two forms, queue and topic. Now use queue Queue queue = session.createQueue("test-queue"); //6. Create a Producer object using the Session object MessageProducer producer = session.createProducer(queue); //7. Create a Message object to use TextMessage maliciously //The first way //TextMessage textMessage = new ActiveMQTextMessage(); //textMessage.setText("hello activemq"); //The second way TextMessage textMessage = session.createTextMessage("hello activemq"); //8. Send message producer.send(textMessage); //9. Close resources producer.close(); session.close(); connection.close(); }
Consumer code
public void queueConsumer() throws Exception { //Create a ConnectionFactory object to connect to the MQ server ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://192.168.25.161:61616"); //Create a connection object Connection connection = connectionFactory.createConnection(); //Open connection connection.start(); //Create a Session object using the Connection object Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); //Create a Destination object, a queue object Queue queue = session.createQueue("test-queue"); //Using Session object to create a consumer object MessageConsumer consumer = session.createConsumer(queue); //receive messages consumer.setMessageListener(new MessageListener() { @Override public void onMessage(Message message) { //Print results TextMessage textMessage = (TextMessage) message; String text; try { text = textMessage.getText(); System.out.println(text); } catch (JMSException e) { e.printStackTrace(); } } }); //Waiting to receive message System.in.read(); //close resource consumer.close(); session.close(); connection.close(); }topic - Publish / subscribe mode
After a producer generates a message and sends it, it can be received by multiple consumers. If no consumer receives it, the message disappears.
Producer code
public void topicProducer() throws Exception{ //1. To create a connection factory object, you need to specify the ip and port of the service ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://192.168.25.161:61616"); //2. Create a Connection object using the factory object Connection connection = connectionFactory.createConnection(); //3. To open a Connection, call the start method of the Connection object connection.start(); //4. Create a Session object //The first parameter: whether to start transaction or not. Generally, transaction is not opened. If transaction is opened, the second parameter is meaningless //The second parameter: response mode, auto response or manual response, general auto response Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); //5. Use Session object to create a Destination object in two forms, queue and topic. Now use topic Topic topic = session.createTopic("test-topic"); //6. Create a Producer object using the Session object MessageProducer producer = session.createProducer(topic); //7. Create a Message object to use TextMessage maliciously //The first way //TextMessage textMessage = new ActiveMQTextMessage(); //textMessage.setText("topic message"); //The second way TextMessage textMessage = session.createTextMessage("topic message"); //8. Send message producer.send(textMessage); //9. Close resources producer.close(); session.close(); connection.close(); }
In fact, the main difference lies in session.createQueue/Topic. The same is true for consumers.
Consumer code
public void topicConsumer() throws Exception { //Create a ConnectionFactory object to connect to the MQ server ConnectionFactory connectionFactory = new ActiveMQConnectionFactory("tcp://192.168.25.161:61616"); //Create a connection object Connection connection = connectionFactory.createConnection(); //Open connection connection.start(); //Create a Session object using the Connection object Session session = connection.createSession(false, Session.AUTO_ACKNOWLEDGE); //Create a Destination object, topic object Topic topic = session.createTopic("test-topic"); //Using Session object to create a consumer object MessageConsumer consumer = session.createConsumer(topic); //receive messages consumer.setMessageListener(new MessageListener() { @Override public void onMessage(Message message) { //Print results TextMessage textMessage = (TextMessage) message; String text; try { text = textMessage.getText(); System.out.println(text); } catch (JMSException e) { e.printStackTrace(); } } }); //Waiting to receive message System.in.read(); //close resource consumer.close(); session.close(); connection.close(); }summary
Message publishing in the form of topic can also be persistent, that is to say, after topic sends a message, if no consumer receives it, the message will be persistent. I will not elaborate here.