3.rabbitmq Work Queues

前言

本文介绍java客户端如何实现工作队列，入下图所示，生产者P生产消息，消息传送到队列，C1,C2轮流消费消息。

image.png

代码

• build.gradle

plugins {
    id 'java'
}

group 'com.nick'
version '1.0-SNAPSHOT'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.12'
    compile group: 'com.rabbitmq', name: 'amqp-client', version: '5.2.0'
    compile group: 'org.slf4j', name: 'slf4j-api', version: '1.7.25'
    compile group: 'org.slf4j', name: 'slf4j-simple', version: '1.7.25'
    compile group: 'org.projectlombok', name: 'lombok', version: '1.18.0'
}

• send.java

package com.nick.workQueues;

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

import java.util.concurrent.TimeoutException;

public class Send {
    private static final String TASK_QUEUE_NAME = "task_queue";

    public static void main(String[] argv)
            throws java.io.IOException, TimeoutException {

        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.5.136");
        Connection connection = factory.newConnection();
        Channel channel = connection.createChannel();

        channel.queueDeclare(TASK_QUEUE_NAME, true, false, false, null);

        String message = "hello work queues";

        channel.basicPublish( "", TASK_QUEUE_NAME,
                MessageProperties.PERSISTENT_TEXT_PLAIN,
                message.getBytes());
        System.out.println(" [x] Sent '" + message + "'");

        channel.close();
        connection.close();
    }
}

• Rev1.java

package com.nick.workQueues;

import com.rabbitmq.client.*;

import java.io.IOException;

public class Rev1 {
    private static final String TASK_QUEUE_NAME = "task_queue";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.5.136");
        final Connection connection = factory.newConnection();
        final Channel channel = connection.createChannel();

        channel.queueDeclare(TASK_QUEUE_NAME, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        final Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message = new String(body, "UTF-8");

                System.out.println(" 1.Received:[x]  '" + message + "'");
                try {
                    doWork(message);
                } finally {
                    System.out.println(" [x] Done");
                    channel.basicAck(envelope.getDeliveryTag(), false);
                }
            }
        };
        boolean autoAck = false;
        channel.basicConsume(TASK_QUEUE_NAME, autoAck, consumer);
    }

    private static void doWork(String task) {
        for (char ch : task.toCharArray()) {
            if (ch == '.') {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException _ignored) {
                    Thread.currentThread().interrupt();
                }
            }
        }
    }
}

• Rev2

package com.nick.workQueues;

import com.rabbitmq.client.*;

import java.io.IOException;

public class Rev2 {
    private static final String TASK_QUEUE_NAME = "task_queue";

    public static void main(String[] argv) throws Exception {
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("192.168.5.136");
        final Connection connection = factory.newConnection();
        final Channel channel = connection.createChannel();

        channel.queueDeclare(TASK_QUEUE_NAME, true, false, false, null);
        System.out.println(" [*] Waiting for messages. To exit press CTRL+C");

        channel.basicQos(1);

        final Consumer consumer = new DefaultConsumer(channel) {
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                String message = new String(body, "UTF-8");

                System.out.println(" 2.Received:[x]  '" + message + "'");
                try {
                    doWork(message);
                } finally {
                    System.out.println(" [x] Done");
                    channel.basicAck(envelope.getDeliveryTag(), false);
                }
            }
        };
        boolean autoAck = false;
        channel.basicConsume(TASK_QUEUE_NAME, autoAck, consumer);
    }

    private static void doWork(String task) {
        for (char ch : task.toCharArray()) {
            if (ch == '.') {
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException _ignored) {
                    Thread.currentThread().interrupt();
                }
            }
        }
    }
}

测试

• 执行Rev1.java
• 执行Rev2.java
• 多次执行执行Send.java，可以看到控制台对应的输出，可以看到接收窗口2个接收进程轮流接收数据；

image.png

image.png

详细代码见

https://github.com/qiujiahong/rabbitmq_study