之前学习的都是一条消息发给一个消费者，下面开始记录如何把一条信息发给多个消费者

这边我们用到了交换机Exchange

交换机模式：fanout

模式特点：生产者把消息发送给Exchange之后，Exchange则会把这些消息添加到与自己绑定的所有队列之中，监听这些队列的消费者就可以收到这些消息。

注：Exchange并不能保存信息，如果没有绑定的队列，那么生产者发送数据就会丢失，只有队列才能存储生产者的消息。

生产者：声明交换机后指定交换机模式fanout

package com.example.demo.queue.exchangeToQueue.fanout;import java.io.IOException;import java.util.concurrent.TimeoutException;import com.example.demo.utils.ConnectionUtil;import com.rabbitmq.client.Channel;import com.rabbitmq.client.Connection;public class Producer {	// exchange名称	private static final String EXCHANGE_NAME = "exchange_fanout"; 		public static void main(String[] args) {		Connection connection = null;		Channel channel = null;		try {			// 获取连接			connection = ConnectionUtil.getConnection();			// 创建通道			channel = connection.createChannel();			// 声明交换机			channel.exchangeDeclare(EXCHANGE_NAME, "fanout", true);			// 生产者发送的信息			String msg = "msg from producer:";			for(int i=0;i<10;i++) {				msg = "msg from producer :" + i;				System.out.println("send msg : "+msg);				// 发送信息				channel.basicPublish(EXCHANGE_NAME, "", null, msg.getBytes());			}		} catch (Exception e) {			e.printStackTrace();		} finally {			// 关闭通道			try {				channel.close();			} catch (IOException e) {				e.printStackTrace();			} catch (TimeoutException e) {				e.printStackTrace();			}			// 关闭连接			try {				connection.close();			} catch (IOException e) {				e.printStackTrace();			}		}			}	}

消费者1：声明队列fanout_exchange_to_queue_01并绑定到交换机exchange_fanout

package com.example.demo.queue.exchangeToQueue.fanout;import java.io.IOException;import com.example.demo.utils.ConnectionUtil;import com.rabbitmq.client.AMQP.BasicProperties;import com.rabbitmq.client.Channel;import com.rabbitmq.client.Connection;import com.rabbitmq.client.DefaultConsumer;import com.rabbitmq.client.Envelope;public class Consumer01 {	// 交换机名称	private static final String EXCHANGE_NAME = "exchange_fanout"; 		// 监听队列名称	private static final String QUEUE_NAME = "fanout_exchange_to_queue_01";		public static void main(String[] args) {		try {			// 获取连接			Connection connection = ConnectionUtil.getConnection();			// 创建通道			final Channel channel = connection.createChannel();			// 声明队列			channel.queueDeclare(QUEUE_NAME, true, false, false, null);			// 绑定队列到交换机			channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "");			// 定义消费者			DefaultConsumer consumer = new DefaultConsumer(channel) {				@Override				public void handleDelivery(String consumerTag, Envelope envelope, BasicProperties properties, byte[] body) throws IOException {					String msg = new String(body,"UTF-8");					System.out.println("[1]:receive msg:"+msg);					System.out.println("[1]:deal msg successful.");				}							};			// 接收信息			channel.basicConsume(QUEUE_NAME, true, consumer);								} catch (Exception e) {			e.printStackTrace();		}	}	}

消费者2：声明队列fanout_exchange_to_queue_02并绑定到交换机exchange_fanout

package com.example.demo.queue.exchangeToQueue.fanout;import java.io.IOException;import com.example.demo.utils.ConnectionUtil;import com.rabbitmq.client.AMQP.BasicProperties;import com.rabbitmq.client.Channel;import com.rabbitmq.client.Connection;import com.rabbitmq.client.DefaultConsumer;import com.rabbitmq.client.Envelope;public class Consumer02 {	// 交换机名称	private static final String EXCHANGE_NAME = "exchange_fanout"; 		// 监听队列名称	private static final String QUEUE_NAME = "fanout_exchange_to_queue_02";		public static void main(String[] args) {		try {			// 获取连接			Connection connection = ConnectionUtil.getConnection();			// 创建通道			final Channel channel = connection.createChannel();			// 声明队列			channel.queueDeclare(QUEUE_NAME, true, false, false, null);			// 绑定队列到交换机			channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "");			// 定义消费者			DefaultConsumer consumer = new DefaultConsumer(channel) {				@Override				public void handleDelivery(String consumerTag, Envelope envelope, BasicProperties properties, byte[] body) throws IOException {					String msg = new String(body,"UTF-8");					System.out.println("[2]:receive msg:"+msg);					System.out.println("[2]:deal msg successful.");				}			};			// 接收信息			channel.basicConsume(QUEUE_NAME, true, consumer);		} catch (Exception e) {			e.printStackTrace();		}	}	}

消费者3：声明队列fanout_exchange_to_queue_03，没有绑定到交换机exchange_fanout

package com.example.demo.queue.exchangeToQueue.fanout;import java.io.IOException;import com.example.demo.utils.ConnectionUtil;import com.rabbitmq.client.AMQP.BasicProperties;import com.rabbitmq.client.Channel;import com.rabbitmq.client.Connection;import com.rabbitmq.client.DefaultConsumer;import com.rabbitmq.client.Envelope;public class Consumer03 {	// 交换机名称	private static final String EXCHANGE_NAME = "exchange_fanout"; 		// 监听队列名称	private static final String QUEUE_NAME = "fanout_exchange_to_queue_03";		public static void main(String[] args) {		try {			// 获取连接			Connection connection = ConnectionUtil.getConnection();			// 创建通道			final Channel channel = connection.createChannel();			// 声明队列			channel.queueDeclare(QUEUE_NAME, true, false, false, null);			// 绑定队列到交换机//			channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "");			// 定义消费者			DefaultConsumer consumer = new DefaultConsumer(channel) {				@Override				public void handleDelivery(String consumerTag, Envelope envelope, BasicProperties properties, byte[] body) throws IOException {					String msg = new String(body,"UTF-8");					System.out.println("[3]:receive msg:"+msg);					System.out.println("[3]:deal msg successful.");				}			};			// 接收信息			channel.basicConsume(QUEUE_NAME, true, consumer);		} catch (Exception e) {			e.printStackTrace();		}	}	}

这次，涉及到了交换机，而在消费者类中中并没有声明交换机，所以需要先执行生产者类的main方法

可以看到生产者已经成功发送消息给交换机，交换机也成功创建了，但是消息数据丢失了，原因就是上面说的，交换机无法保存从生产者那接收到的信息，只有队列可以保存消息。

接下来，我们就可以依次执行三个消费者类的main方法，之后再执行生产者类的main方法。

消费者1终端：

消费者2终端：

消费者3终端：