RabbitMQ教程-消息的两种消费模式

谁借莪１个温暖的怀抱￠ 2023-01-11 01:10 173阅读 0赞

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### 消费模式 ###

RabbitMQ消费模式有两种，一种是队列的push，另外一个是从队列pull。对应API如下。

*  pull: com.rabbitmq.client.Channel\#basicGet。消息中间件主动将消息推送给消费者
 *  push: com.rabbitmq.client.Channel\#basicConsume。消费者主动从消息中间件拉取消息

### 两种模式的区别 ###

*  push:推模式接收消息是最有效的一种消息处理方式。当我们使用该模式的时候，我们的消费端，只需要启动了之后，就会相当于使用了订阅模式，只要生产端不断推送消息，消费端就会持续接收到消息。
 *  pull:拉模式接收消息和push是完全不同的，它每次接收消息都需要去拉取一下队列的信息。由于是拉取的，实时性较差。不能及时有效的获取最新的消息，所以相对来说使用并不是很多。但是该模式对于部分业务量很小的功能来说确实一个不错的选择，能有效的降低对内存的消耗。

### push模式的实例 ###

import com.rabbitmq.client.*;
    import lombok.SneakyThrows;
    
    import java.io.IOException;
    import java.util.concurrent.TimeUnit;
    import java.util.concurrent.TimeoutException;
    
    /**
     * @author echo
     * @date 2021-01-14 15:05
     */
    public class TopicConsumerTest {
        
    
        private static final String EXCHANGE_NAME = "exchange_topic";
        private static final String QUEUE_NAME = "queue_topic1";
        private static final String IP_ADDRESS = "192.168.230.131";
        private static final int PORT = 5672;
    
        public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
        
    
            ConnectionFactory factory = new ConnectionFactory();
            // 设置RabbitMQ的链接参数
            factory.setUsername("echo");
            factory.setPassword("123456");
            factory.setPort(PORT);
            factory.setHost(IP_ADDRESS);
    
            // 和RabbitMQ建立一个链接
            Connection connection = factory.newConnection();
            final Channel channel = connection.createChannel();
            //声明交换机 Fanout模式
            channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC, true, false, null);
            //进行绑定，指定消费那个队列
            channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "", null);
            Consumer consumer = new DefaultConsumer(channel) {
        
                @SneakyThrows
                @Override
                public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) {
        
                    System.out.println("recv message: " + new String(body));
                    try {
        
                        TimeUnit.SECONDS.sleep(1);
                    } catch (InterruptedException e) {
        
                        e.printStackTrace();
                    }
                    channel.basicAck(envelope.getDeliveryTag(), false);
                }
            };
            channel.basicConsume(QUEUE_NAME, consumer);
            //等待回调函数执行完毕之后 关闭资源
            TimeUnit.SECONDS.sleep(5);
            channel.close();
            connection.close();
        }
    
    }

### pull模式实例 ###

import com.rabbitmq.client.*;
    
    import java.io.IOException;
    import java.util.concurrent.TimeUnit;
    import java.util.concurrent.TimeoutException;
    
    /**
     * @author echo
     * @date 2021-01-14 15:05
     */
    public class TopicConsumerTest {
        
    
        private static final String EXCHANGE_NAME = "exchange_topic";
        private static final String QUEUE_NAME = "queue_topic1";
        private static final String IP_ADDRESS = "192.168.230.131";
        private static final int PORT = 5672;
    
        public static void main(String[] args) throws IOException, TimeoutException, InterruptedException {
        
    
            ConnectionFactory factory = new ConnectionFactory();
            // 设置RabbitMQ的链接参数
            factory.setUsername("echo");
            factory.setPassword("123456");
            factory.setPort(PORT);
            factory.setHost(IP_ADDRESS);
    
            // 和RabbitMQ建立一个链接
            Connection connection = factory.newConnection();
            final Channel channel = connection.createChannel();
            //声明交换机 Fanout模式
            channel.exchangeDeclare(EXCHANGE_NAME, BuiltinExchangeType.TOPIC, true, false, null);
            //进行绑定，指定消费那个队列
            channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "", null);
            GetResponse getResponse = channel.basicGet(QUEUE_NAME, false);
            System.out.println(new String(getResponse.getBody()));
            //等待回调函数执行完毕之后 关闭资源
            TimeUnit.SECONDS.sleep(5);
            channel.close();
            connection.close();
        }
    
    }