RabbitMQ高级应用之消费端限流策略basicQos详解

channel.basicQos(); 

// 生产者
public class Producer {
    private static final String QUEUE_NAME = "queue_limit_1";
    public static void main(String[] args) throws IOException, TimeoutException {
        Connection connection = ConnectionUtils.getConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);
        for (int i = 0; i < 100; i++) {
            channel.basicPublish("", QUEUE_NAME, null, ("消费端限流策略—测试数据：" + i).getBytes());
        }
        channel.close();
        connection.close();
    }
}

// 消费者1
public class Consumer {
    private static final String QUEUE_NAME = "queue_limit_1";
    public static void main(String[] args) throws IOException, TimeoutException {
        Connection connection = ConnectionUtils.getConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);
        DefaultConsumer defaultConsumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                System.out.println("消费者1接收到信息：" + new String(body));
                channel.basicAck(envelope.getDeliveryTag(), false);
            }
        };
        channel.basicConsume(QUEUE_NAME, false, defaultConsumer);
    }
}

// 消费者2
public class Consumer2 {
    private static final String QUEUE_NAME = "queue_limit_1";
    public static void main(String[] args) throws IOException, TimeoutException {
        Connection connection = ConnectionUtils.getConnection();
        Channel channel = connection.createChannel();
        channel.queueDeclare(QUEUE_NAME, false, false, false, null);
        /**  设置限流机制
         *  param1: prefetchSize，消息本身的大小 如果设置为0  那么表示对消息本身的大小不限制
         *  param2: prefetchCount，告诉rabbitmq不要一次性给消费者推送大于N个消息
         *  param3：global，是否将上面的设置应用于整个通道，false表示只应用于当前消费者
         */
        channel.basicQos(0, 5, false);
        DefaultConsumer defaultConsumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                System.out.println("消费者2接收到信息：" + new String(body));
                channel.basicAck(envelope.getDeliveryTag(), false);
                try {
                    Thread.sleep(200);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };
        channel.basicConsume(QUEUE_NAME, false, defaultConsumer);
    }
}

/**
     * @param prefetchSize maximum amount of content (measured in
     * octets) that the server will deliver, 0 if unlimited
     * @param prefetchCount maximum number of messages that the server
     * will deliver, 0 if unlimited
     * @param global true if the settings should be applied to the
     * entire channel rather than each consumer
     */
    void basicQos(int prefetchSize, int prefetchCount, boolean global) throws IOException;