RabbitMQ高级特性-死信队列

时间 2019-12-21

标签 rabbitmq 高级特性死信队列栏目 RabbitMQ 繁體版

原文原文链接

[TOC]java

死信

什么是死信

消息没有任何消费者去消费就变为死信ide

消息变为死信有如下几种状况

消息被拒绝(basic.reject/basic.nack),而且requeue=false
消息TTL过时
队列达到最大长度

死信队列 Dead Letter Exchange(DLX)

DLX

利用DLX，当消息在一个队列中变成死信以后，它能被从新publish到另一个exchange,这个exchange就是DLX。ui

DLX也是一个正常的Exchange,和通常的Exchange没有区别，它能在任何队列上被指定，实际就是设置某个队列的属性。当队列中有死信时，RabbitMQ会自动将死信消息发送到设置的DLX，进而被路由到另一个队列，能够监听这个队列，作后续处理。spa

死信队列设置

申明死信队列的Exchange和queue，而后进行绑定
申明正常队列Exchange和queue绑定，只不过要在队列上加参数 arguments.put(x-dead-letter-exchange", "you dlx");

代码实现

producer

package com.wyg.rabbitmq.javaclient.dlx;

import java.io.IOException;
import java.util.concurrent.TimeoutException;

import com.rabbitmq.client.AMQP;
import com.rabbitmq.client.Channel;
import com.rabbitmq.client.Connection;
import com.rabbitmq.client.ConnectionFactory;

/**
 * 消费者手工ack和nack
 * 
 * @author wyg0405@gmail.com
 * @date 2019-11-22 13:25
 * @since JDK1.8
 * @version V1.0
 */

public class Producer {
    private static final String HOST = "localhost";
    private static final int PORT = 5672;
    private static final String USERNAME = "guset";
    private static final String PASSWORD = "guset";

    public static void main(String[] args) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(HOST);
        factory.setVirtualHost("/");
        factory.setPort(PORT);
        factory.setUsername(USERNAME);
        factory.setPassword(PASSWORD);
        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();
        String exchangeName = "test_dlx_exchange";
        String routingKey = "dlx.abc";
        // 申明exchange
        channel.exchangeDeclare(exchangeName, "topic");

        String msg = "正常消息1,routingKey:" + routingKey;
        AMQP.BasicProperties props = new AMQP.BasicProperties.Builder().deliveryMode(2).expiration("2000").build();
        channel.basicPublish(exchangeName, routingKey, false, null, msg.getBytes("UTF-8"));
        // 该消息无消费者消费
        String msg2 = "过时死信消息2，routingKey:" + routingKey;
        channel.basicPublish(exchangeName, routingKey, false, props, msg2.getBytes("UTF-8"));
        String msg3 = "过时死信消息3，routingKey:" + routingKey;
        channel.basicPublish(exchangeName, routingKey, false, props, msg3.getBytes("UTF-8"));
        String msg4 = "过时死信消息4，routingKey:" + routingKey;
        channel.basicPublish(exchangeName, routingKey, false, props, msg4.getBytes("UTF-8"));
        channel.close();
        connection.close();
    }

}

producer能够采用消息过时产生死信code

正常consumer

package com.wyg.rabbitmq.javaclient.dlx;

import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;

import com.rabbitmq.client.*;

/**
 * 消费者手工ack和nack
 * 
 * @author wyg0405@gmail.com
 * @date 2019-11-22 14:07
 * @since JDK1.8
 * @version V1.0
 */

public class Consumer {

    private static final String HOST = "localhost";
    private static final int PORT = 5672;
    private static final String USERNAME = "guset";
    private static final String PASSWORD = "guset";

    public static void main(String[] args) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(HOST);
        factory.setVirtualHost("/");
        factory.setPort(PORT);
        factory.setUsername(USERNAME);
        factory.setPassword(PASSWORD);
        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        // 定义死信队的Exchange
        String dlxExchange = "dlx.exchange";
        channel.exchangeDeclare(dlxExchange, "topic");
        // 死信队列名
        String dlxQueue = "dlx.queue";
        channel.queueDeclare(dlxQueue, true, false, false, null);
        // # 表示全部的key均可以路由到s死信队列
        String dlxRoutingKey = "#";
        // 绑定死信队列和exchange
        channel.queueBind(dlxQueue, dlxExchange, dlxRoutingKey, null);

        // 定义正常的消费者j监听队列
        String queueName = "test_dlx_queue";
        String exchangeName = "test_dlx_exchange";
        String routingKey = "dlx.#";
        // 申明exchange
        channel.exchangeDeclare(exchangeName, "topic");
        // 申明队列

        Map<String, Object> arguments = new HashMap<>();
        // 设置死信队列,arguments要设置到申明的队列上
        arguments.put("x-dead-letter-exchange", dlxExchange);
        channel.queueDeclare(queueName, true, false, false, arguments);
        // 队列绑定到exchange
        channel.queueBind(queueName, exchangeName, routingKey);
        channel.basicQos(1);

        DeliverCallback deliverCallback = new DeliverCallback() {
            @Override
            public void handle(String consumerTag, Delivery message) throws IOException {

                try {
                    TimeUnit.SECONDS.sleep(3);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println("---消费者-- " + new String(message.getBody(), "UTF-8"));

            }
        };
        CancelCallback cancelCallback = new CancelCallback() {
            @Override
            public void handle(String consumerTag) throws IOException {
                System.out.println("---消费者--：cancelCallback ");
            }
        };

        // 消费消息,autoAck必定要设为false，手工ack
        channel.basicConsume(queueName, false, deliverCallback, cancelCallback);
    }
}

运行结果：只消费一条正常消息，其余过时的未消费blog

DLXConusmer,监听消费死信队列中的消息

package com.wyg.rabbitmq.javaclient.dlx;

import java.io.IOException;
import java.util.concurrent.TimeoutException;

import com.rabbitmq.client.*;

/**
 * 监听私信队列
 * 
 * @author wyg0405@gmail.com
 * @date 2019-11-22 21:52
 * @since JDK1.8
 * @version V1.0
 */

public class DLXConusmer {
    private static final String HOST = "localhost";
    private static final int PORT = 5672;
    private static final String USERNAME = "guset";
    private static final String PASSWORD = "guset";

    public static void main(String[] args) throws IOException, TimeoutException {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost(HOST);
        factory.setVirtualHost("/");
        factory.setPort(PORT);
        factory.setUsername(USERNAME);
        factory.setPassword(PASSWORD);
        Connection connection = factory.newConnection();

        Channel channel = connection.createChannel();

        String queueName = "dlx.queue";
        String exchangeName = "dlx.exchange";
        String routingKey = "#";

        // 申明exchange
        channel.exchangeDeclare(exchangeName, "topic");
        // 申明队列
        channel.queueDeclare(queueName, true, false, false, null);
        // 队列绑定到exchange
        channel.queueBind(queueName, exchangeName, routingKey, null);

        DeliverCallback deliverCallback = new DeliverCallback() {
            @Override
            public void handle(String consumerTag, Delivery message) throws IOException {
                try {
                    System.out.println("---死信队列消费者---");
                    System.out.println(new String(message.getBody(), "UTF-8"));
                } finally {
                    // consumer手动 ack 给broker
                    channel.basicAck(message.getEnvelope().getDeliveryTag(), false);
                }
            }
        };
        CancelCallback cancelCallback = new CancelCallback() {
            @Override
            public void handle(String consumerTag) throws IOException {
                System.out.println("---消费者：cancelCallback");
            }
        };

        // 消费消息,autoAck必定要设置为false
        channel.basicConsume(queueName, false, deliverCallback, cancelCallback);
    }
}

运行结果：3条过时的消息进入死信队列，并被消费rabbitmq