总结一下几种ExchangeTypes。

即producer不是将消息直接放到队列中，而是先到exchange中，exchange主要用于控制消息到队列的路由,根据具体的exchange type将消息传给需要的队列或者直接废弃。

在这一篇中总结一下那些用到的exchange type。

一.Direct Exchange

direct exchange算是最基本的了。

direct exchange用于将带上routing key的消息传值拥有相同routing key的队列中。

当我们想用一个简单的标识符区别所有传入同一个exchange中的消息时direct exchange就非常合适。

代码如下：

private static String DIRECT_EXCHANGE = "DIRECT_EXCHAGNE";

    static class FanoutProducer {

        public static void main(String[] args) throws IOException {

            ConnectionFactory connectionFactory = new ConnectionFactory();

            Connection connection = connectionFactory.newConnection();

            Channel channel= connection.createChannel();;

            String content = "I miss the conversation";

            channel.exchangeDeclare(DIRECT_EXCHANGE, ExchangeTypes.DIRECT);

            channel.basicPublish(DIRECT_EXCHANGE, "alvez", null, content.getBytes());

        }

    }

    static class FanoutConsumer {

        public static void main(String[] args) throws IOException, InterruptedException {

            ConnectionFactory connectionFactory = new ConnectionFactory();

            Connection connection = connectionFactory.newConnection();

            Channel channel= connection.createChannel();

            String queueName = channel.queueDeclare().getQueue();

            channel.queueBind(queueName, DIRECT_EXCHANGE, "alvez");

            QueueingConsumer consumer = new QueueingConsumer(channel);

            String s = channel.basicConsume(queueName, true, consumer);

            System.out.println(s);

            while (true) {

                QueueingConsumer.Delivery delivery = consumer.nextDelivery();

                String message = new String(delivery.getBody());

                String routingKey = delivery.getEnvelope().getRoutingKey();

                System.out.println("From:" + routingKey + "':'" + message + "'");

            }

        }

二.Fanout Exchange

fanout和routing key无关，它将消息无差别地(indiscriminately)传送给所有队列。

fanout exchange通常用于发布/订阅模式。

将消息传送给不同的队列，不同的队列对同一种消息采取不同的行为。

比如，现在有一个客户订单消息被三个队列接收，队列1完成该订单，队列2将订单写入日志，队列3将订单发给别的部门什么的。

比如下面的代码，消费者可以获得routing key并输出，但能否获取与routing key无关：

private static String FANOUT_EXCHANGE = "FANOUT_EXCHANGE";

static class DirectProducer {

public static void main(String[] args) throws IOException {

ConnectionFactory connectionFactory = new ConnectionFactory();

Connection connection = connectionFactory.newConnection();

Channel channel= connection.createChannel();;

String content = "I miss the conversation";

channel.exchangeDeclare(FANOUT_EXCHANGE, ExchangeTypes.FANOUT);

channel.basicPublish(FANOUT_EXCHANGE, "alvez", null, content.getBytes());

}

}

static class DirectConsumer {

public static void main(String[] args) throws IOException, InterruptedException {

ConnectionFactory connectionFactory = new ConnectionFactory();

Connection connection = connectionFactory.newConnection();

Channel channel= connection.createChannel();

String queueName = channel.queueDeclare().getQueue();

channel.queueBind(queueName, FANOUT_EXCHANGE, "");

QueueingConsumer consumer = new QueueingConsumer(channel);

String s = channel.basicConsume(queueName, true, consumer);

System.out.println(s);

while (true) {

QueueingConsumer.Delivery delivery = consumer.nextDelivery();

String message = new String(delivery.getBody());

String routingKey = delivery.getEnvelope().getRoutingKey();

System.out.println("From:" + routingKey + "':'" + message + "'");

}

}

}

希望这篇文章可以帮助到你。总之，同学们，你想要的职坐标IT频道都能找到！