RabbitMQ之轮询模式

	在这个案例中我们会启动两个工作线程，一个消息发送线程，两个工作线程。然后在发送线程中不断发送消息，验证两个工作线程是以何种方式拿到消息的。

public class ExerciseT {
    private static final String QUEUE_NAME = "hello";

    public static void main(String[] args) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(You host address);
        factory.setUsername(username);
        factory.setPassword(password);
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);

        //Receive messages from console
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String message = scanner.next();
            channel.basicPublish("", QUEUE_NAME, null,message.getBytes());
            System.out.println("Message has delivered：" + message);
        }
    }
}

@Slf4j
public class ExerciseW {
    private static final String QUEUE_NAME = "hello";

    public static void main(String[] args) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.121.36");
        factory.setUsername("admin");
        factory.setPassword("123");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();
        //lambda expression
        DeliverCallback deliverCallback = (consumerTag, message) -> {
            log.info("Worker1 has receive message："+new String(message.getBody()),"UTF-8");
        };
        //lambda expression
        CancelCallback cancelCallback = consumerTag -> {
            log.info("Worker1 message has  been canceled!");
        };
        channel.basicConsume(QUEUE_NAME,false,deliverCallback,cancelCallback);
    }
}

启动另外一个工作线程的方式就是直接把上面那个工作线程中的Worker1改成worker2就行了。
在idea中设置允许并行运行即可，如下如所示

运行效果如下图所示：
消息发送线程：发送44，55，66，77
接收消息线程效果图1：

接收消息线程效果图2：

结论：消息发送线程，发送消息时工作线程会轮询得到消息发送线程发送的消息，这是一种公平的策略，但是这种方式效率较低，在实际工作中一般采用不公平的策略 。