mqtt模式--Work 模式--轮询分发

当有多个消费者时，如何均衡消息者消费消息的多少，主要有两种模式：

轮询模式分发：按顺序轮询分发，每个消费者获得相同数量的消息
公平分发：根据消费者消费能力公平分发，处理快的处理的多，处理慢的处理的少，按劳分配

轮询分发
在这种模式下，rabbitmq 采用轮询的方式将任务分配给多个消费者，但可能出现一种情况，当分配给某一个消费者的任务很复杂时，而有些消费者接收的任务较轻量，会出现有的消费者很忙，而有的消费者处于空闲的状态，而 rabbitmq 不会感知到这种情况的发生，rabbitmq 不考虑消费者未确认消息的数量，只是盲目的分配任务。

package com.tszr.work;

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

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.TimeoutException;

public class Productor {
    public static void main(String[] args){
        // 1、创建连接工程
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("127.0.0.1");
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setVirtualHost("/");

        Connection connection = null;
        Channel channel = null;
        try {
            // 2、获取连接、通道
            connection = factory.newConnection();
            channel = connection.createChannel();

            // 3、向 Queue1 发布20个消息
            for (int i = 0; i < 20; i++) {
                String msg = "晴天: " + i;
                channel.basicPublish("", "queue1", null, msg.getBytes(StandardCharsets.UTF_8));
            }
            System.out.println("消息发送成功!");
        } catch (IOException | TimeoutException e) {
            e.printStackTrace();
            System.out.println("消息发送异常");
        } finally {
            // 关闭通道
            if (channel != null && channel.isOpen()) {
                try {
                    channel.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            // 关闭连接
            if (connection != null && connection.isOpen()) {
                try {
                    connection.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

package com.tszr.work;

import com.rabbitmq.client.*;

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

public class Worker2 {
    public static void main(String[] args) {
        // 1、创建连接工厂
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("127.0.0.1");
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setVirtualHost("/");

        Connection connection = null;
        Channel channel = null;
        try {
            // 获取连接、通道
            connection = factory.newConnection();
            channel = connection.createChannel();
            Channel finalChannel = channel;
            finalChannel.basicConsume("queue1", true, new DeliverCallback() {
                @Override
                public void handle(String consumerTag, Delivery delivery) throws IOException {
                    System.out.println("Worker2" + ":收到消息是：" + new String(delivery.getBody(), "UTF-8"));
                    try {
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }, new CancelCallback() {
                @Override
                public void handle(String consumerTag) throws IOException {
                }
            });
            System.out.println("Worker2 开始接收消息");
            System.in.read();
        } catch (IOException |
                TimeoutException e) {
            e.printStackTrace();
        } finally {
            // 关闭通道
            if (channel != null && channel.isOpen()) {
                try {
                    channel.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            // 关闭连接
            if (connection != null && connection.isOpen()) {
                try {
                    connection.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}

package com.tszr.work;

import com.rabbitmq.client.*;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.TimeoutException;

public class Worker1 {
    public static void main(String[] args) {
        // 1、创建连接工厂
        ConnectionFactory factory = new ConnectionFactory();
        factory.setHost("127.0.0.1");
        factory.setUsername("guest");
        factory.setPassword("guest");
        factory.setVirtualHost("/");

        Connection connection = null;
        Channel channel = null;
        try {
            // 获取连接、通道
            connection = factory.newConnection();
            channel = connection.createChannel();
            Channel finalChannel = channel;
            finalChannel.basicConsume("queue1", true, new DeliverCallback() {
                @Override
                public void handle(String consumerTag, Delivery delivery) throws IOException {
                    System.out.println("Worker1" + ":收到消息是：" + new String(delivery.getBody(), "UTF-8"));
                    try {
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }, new CancelCallback() {
                @Override
                public void handle(String consumerTag) throws IOException {
                }
            });
            System.out.println("Worker1 开始接收消息");
            System.in.read();
        } catch (IOException |
                TimeoutException e) {
            e.printStackTrace();
        } finally {
            // 关闭通道
            if (channel != null && channel.isOpen()) {
                try {
                    channel.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            // 关闭连接
            if (connection != null && connection.isOpen()) {
                try {
                    connection.close();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }
}