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Topic exchange

direct类型的Exchange路由规则是完全匹配binding key与routing key，但这种严格的匹配方式在很多情况下不能满足实际业务需求。topic类型的Exchange在匹配规则上进行了扩展，它与direct类型的Exchage相似，也是将消息路由到binding key与routing key相匹配的Queue中，但匹配规则有些不同
routing_key-它必须是单词列表，以点分隔。这些词可以是任何东西，但是通常它们指定与消息相关的某些功能。一些有效的rounting key 如："stock.usd.nyse"，"nyse.vmw"，"quick.orange.rabbit"。rounting key中可以包含任意多个单词，最多255个字节。
binding key可以存在如下两种特殊的字符即：
1、*（星号）可以代替一个单词。
2、＃（哈希）可以替代零个或多个单词

在上面图片中,Routing key 设置为"quick.orange.rabbit"的消息将传递到两个队列。消息"lazy.orange.elephant"也将发送给他们两个。但，"quick.orange.fox"只会进入第一个队列，而"lazy.brown.fox"只会进入第二个队列。"lazy.pink.rabbit"将被传递到第二队只有一次，即使两个绑定匹配。"quick.brown.fox"与任何绑定都不匹配，因此将被丢弃。
如果我们发送一个或四个单词的消息，例如"orange"或"quick.orange.male.rabbit",这些消息将不匹配任何绑定,并且将会丢失。但"lazy.orange.male.rabbit"即使有四个单词，也将匹配最后一个绑定，并将其传送到第二个队列。

生产者消费者代码：

生产者

public class TopicEmitLog {
    private static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception {
        //获取连接
        Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");

        Channel channel = connection.createChannel();

        //创建队列
        //channel.queueDeclare("direct_loge",true,false,false,null);
        //声明交换机，
        channel.exchangeDeclare(EXCHANGE_NAME, "topic");

        String message="hello";
        //发送消息

        //发送消息
        channel.basicPublish(EXCHANGE_NAME, "topics.log", null, message.getBytes("utf-8"));

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

    }

}

消费者1可以收到消息

public class TopicRecv {

    public static final String QUEUE_NAME = "topic_queues";

    public static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception{
        //获取连接
        Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");

        //声明通道
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        //声明队列队列
        channel.queueDeclare(QUEUE_NAME,false,false,false,null);
        //4.绑定队列到交换器,指定路由key为topics
        channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topics.#");

        //
        //channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topic.*");

        DeliverCallback deliverCallback = new DeliverCallback(){
            @Override
            public void handle(String consumerTag, Delivery delivery) throws IOException {
                String message = new String(delivery.getBody(), "UTF-8");
                System.out.println(" [x] Received '" + message + "'");
            }
        };

        channel.basicConsume(QUEUE_NAME, true, deliverCallback, new CancelCallback(){
            @Override
            public void handle(String consumerTag) throws IOException {

            }
        });

    }

}

消费者2收不到消息

public class TopicRecv2 {

    public static final String QUEUE_NAME = "topic_queues2";

    public static final String EXCHANGE_NAME = "topic_logs";

    public static void main(String[] args) throws Exception{
        //获取连接
        Connection connection = ConnectionUtil.getConnection("localhost", 5672, "/", "guest", "guest");

        //声明通道
        Channel channel = connection.createChannel();

        channel.exchangeDeclare(EXCHANGE_NAME, "topic");
        //声明队列队列
        channel.queueDeclare(QUEUE_NAME,false,false,false,null);
        //4.绑定队列到交换器,指定路由key为topics
        //channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topics.#");

        //
        channel.queueBind(QUEUE_NAME, EXCHANGE_NAME, "topic.*");

        DeliverCallback deliverCallback = new DeliverCallback(){
            @Override
            public void handle(String consumerTag, Delivery delivery) throws IOException {
                String message = new String(delivery.getBody(), "UTF-8");
                System.out.println(" [x] Received '" + message + "'");
            }
        };

        channel.basicConsume(QUEUE_NAME, true, deliverCallback, new CancelCallback(){
            @Override
            public void handle(String consumerTag) throws IOException {

            }
        });

    }

}

相关代码链接： https://github.com/albert-liu435/springmq

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