Routing(路由)

        在Fanout模式中，一条消息，会被所有的消费者都消费。但是，在某些场景下，我们希望不同的消息被不同的队列消费。这时就要用到Direct类型的Exchange。

        在Direct模型下，消息的发送方在向Exchange发送消息时，需要指定消息的Routingkey，并且队列与交换机的绑定时也需要指定一个Routingkey。Exchange不再把消息交给每一个绑定的队列，而是根据消息的Routingkey进行判断，只有队列的Routingkey与消息的Routingkey完全一致，队列才会接收到消息。  

1.开发生产者

public class Provider {
    public static void main(String[] args) throws IOException {
        Connection connection = RabbitMqUtil.getConnection();
        Channel channel = connection.createChannel();
        String exchange = "routingexchange";
        //将通道声明指定交换机 参数1：指明交换机名称  参数2：交换机的类型 fanout广播类型
        channel.exchangeDeclare(exchange,"direct");
        //发送消息
        String routingKey = "error";
        channel.basicPublish(exchange,routingKey,null,("这是routingexchange发布的"+routingKey+"消息").getBytes());
        //释放资源
        RabbitMqUtil.closeConnectionAndChannel(channel,connection);
    }
}

2.开发消费者(error)

public class Consumer1 {
    public static void main(String[] args) throws IOException {
        //获取连接对象
        Connection connection = RabbitMqUtil.getConnection();
        //获取连接通道
        Channel channel = connection.createChannel();
        String exchange = "routingexchange";
        //通道绑定交换机
        channel.exchangeDeclare(exchange,"direct");
        //临时队列
        String queueName = channel.queueDeclare().getQueue();
        //基于RoutingKey绑定交换机和队列
        channel.queueBind(queueName,exchange,"error");
        channel.basicConsume(queueName,true,new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                System.out.println("consumer1得到："+new String(body));
            }
        });
        //注意这里不能关闭通道和连接，因为要一直监听
    }
}

3.开发消费者(Info、error、warning)

public class Consumer2 {
    public static void main(String[] args) throws IOException {
        //获取连接对象
        Connection connection = RabbitMqUtil.getConnection();
        //获取连接通道
        Channel channel = connection.createChannel();
        String exchange = "routingexchange";
        //通道绑定交换机
        channel.exchangeDeclare(exchange,"direct");
        //临时队列
        String queueName = channel.queueDeclare().getQueue();
        //基于RoutingKey绑定交换机和队列
        channel.queueBind(queueName,exchange,"info");
        channel.queueBind(queueName,exchange,"error");
        channel.queueBind(queueName,exchange,"warning");
        channel.basicConsume(queueName,true,new DefaultConsumer(channel){
            @Override
            public void handleDelivery(String consumerTag, Envelope envelope, AMQP.BasicProperties properties, byte[] body) throws IOException {
                System.out.println("consumer2得到："+new String(body));
            }
        });
        //注意这里不能关闭通道和连接，因为要一直监听
    }
}

4.结果分析

        消费者1只能接收消息路由为error的消息，而消费者2可以接收消息路由为info、error、warning的消息。